HomeMy WebLinkAboutItem No. 18 - Updated Master Drainage Plan and Fee Schedule
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REPORT TO CITY COUNCIL
To:Honorable Mayor or Members of the City Council
From:Jason Simpson, City Manager
Prepared by:Remon Habib, City Engineer
Date:April 25, 2023
Subject:Updated Master Drainage Plan and Fee Schedule
Recommendation
Adopt A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF LAKE ELSINORE,
CALIFORNIA, ADOPTING AN UPDATED MASTER DRAINAGE PLAN AND FEE SCHEDULE.
Background
On September 14, 2021, City Council approved the Professional Services Agreement with Albert
A. Webb Associates to update and finalize the Master Drainage Plan. This update will provide
necessary Master Drainage Plan updates including a establishing a new Drainage Area Map and
Fee Schedule and a GIS Drainage Map Interface.
Discussion
Albert A. Webb Associates updated the hydrology and hydraulic elements of the Master Drainage
Plan and identified the critical flood control and drainage infrastructure improvements for the safe
and orderly economic development of the community.
The Master Drainage Plan update focused on updating the Drainage Fee Schedule and redefining
drainage areas. The Master Drainage Plan update consolidates 52 drainage areas to 5 drainage
areas with associated updated drainage fees. The updated Drainage Area fees will increase to
the recommended fee over three years. The update also provides an interactive GIS based
Drainage Area Fee Map. In addition, the Master Drainage Plan update identified a list of 12 Capital
Improvement Projects with estimated costs of $1.5 Million or less for the City to evaluate as
funding becomes available.
The City of Lake Elsinore met with members of the Building Industry Association (BIA) of Southern
California – The Riverside Chapter on January 10, 2023 and presented the proposed Master
Drainage Plan and new area drainage fees.
Master Drainage Plan and Fee Schedule
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The Updated Master Drainage Plan identifies the impacts of new development, the increased
necessity for flood protection facilities and the required drainage mitigation projects. The drainage
lines identified are necessary to mitigate flood risk from future development based on the benefit
areas outlined in the Plan.
The proposed Fee Schedule is a financing mechanism used to offset taxpayer costs for new
drainage facilities by calculating the cost of such facilities and spreading that cost among new
development in each drainage area. The Updated Master Drainage Plan formulates an impact
per gross acre as a result of future development. Because drainage is a function of watershed
and rainfall date corresponding to the region, it is more appropriate to calculate the fee based on
gross acreages rather than square footage and density of future structures. Fees based on the
gross acreage of future development is more equitable as it is not functionally related to the size
and density of development.
Fiscal Impact
Fiscal Impact to the City will result in revenue from area drainage fees according to the updated
Master Drainage Plan and updated Area Drainage Fee Schedule below. Funds will be utilized for
Drainage and Street Improvement projects carried out by the City or as reimbursement for
qualified drainage projects carried out be developers and benefiting areas of the City beyond the
project site as authorized by the City Engineer.
Attachments
Attachment 1 – Resolution
Attachment 2 - Updated Master Drainage Plan
RESOLUTION NO. 2023-___
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF LAKE ELSINORE,
CALIFORNIA, ADOPTING AN UPDATED MASTER DRAINAGE PLAN AND
FEE SCHEDULE
Whereas, the City of Lake Elsinore has established drainage fees for the Master Drainage
plan by Resolution 91-63 on August 13, 1991;
Whereas, the City awarded a Professional Services Agreement to Albert A. Webb
Associates on September 14, 2021 to update the City’s Master Drainage Plan and area drainage
fees;
Whereas, the updated Master Drainage Plan reduces the number of benefit areas to five
benefit areas, namely Alberhill Zone, Temescal Wash Zone, Lake Zone, East Lake Zone, and
West Elsinore Zone aiming to simplify administration of area drainage fee;
Whereas, the updated Master Drainage Plan identifies the impacts of new development,
the increased necessity for flood protection facilities and the required drainage mitigation projects;
Whereas, the updated Master Drainage Plan calculates the cost of such facilities and
spreads that cost among new development in each drainage area based on the impact of future
development per gross acre and proposes a new Drainage Fee Schedule based on the gross
acreage of the future development;
Whereas, the City intends to utilize funding provided by the drainage fee for drainage and
street improvement projects administered by the City and as reimbursement for developers where
drainage facilities built by the project provide additional benefit beyond the project site as
approved by the City Engineer;
Whereas, the City intends to implement the new area drainage fees recommended by the
consultant over three (3) years in order to lessen impact to the development community;
Whereas, the City of Lake Elsinore met with members of the Building Industry Association
(BIA) of Southern California – The Riverside Chapter on January 10, 2023 and presented the
updated Master Drainage Plan and new Drainage Fee Schedule;
Whereas, the City of Lake Elsinore, will apply a 3.0% yearly area drainage fee increase
effective March 1st, 2026 and on March 1st for every year thereafter; and
Whereas, the drainage area fee required to be paid by a development project will be
based on effective fee at the time payment is made to the City.
NOW, THEREFORE, THE CITY COUNCIL OF THE CITY OF LAKE ELSINORE DOES
HEREBY RESOLVE, DETERMINE AND ORDER AS FOLLOWS:
Section 1. The City hereby adopts the 2023 Master Drainage Plan and the updated fees
per the following schedule:
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descriptions.doc
CC Reso No. 2023-___
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Benefit Area (Zone)Area Drainage Fee
per gross acre
Effective July 1st,
2023
Area Drainage Fee
per gross acre
Effective July 1st,
2024
Area Drainage Fee
per gross acre
Effective July 1st,
2025
Alberhill Zone $13,769 $21,295 $29,049
Temescal Wash
Zone
$7,561 $10,094 $12,703
Lake Zone $6,802 $8,233 $9,707
East Lake Zone $9,467 $14,171 $19,017
West Lake Zone $6,920 $9,149 $11,445
Section 2. The City Council makes the following findings:
(a) the Updated Master Drainage Plan identifies the impacts of new development, the
increased necessity for flood protection facilities and required drainage mitigation projects;
(b) the drainage lines identified are necessary to mitigate flood risk from future
development based on the benefit areas outlined in the Updated Master Drainage Plan;
(c) because drainage is a function of watershed and rainfall date corresponding to the
region, it is more appropriate to calculate the fee based on gross acreages rather than square
footage and density of future structures;
(d) drainage fees based on the gross acreage of future development are more
equitable as they are not functionally related to the size and density of development; and
(e) the updated Drainage Fee Schedule equitable spreads the cost of new facilities
based on impacts per gross acre of future development.
Section 3. This Resolution shall take effect immediately upon its adoption and the updated
Drainage Fees will become effective in accordance with the adopted schedule commencing July
1, 2023.
Section 4. The City Clerk shall certify to the adoption of this Resolution and enter it into
the book of original Resolutions.
Passed and Adopted at a regular meeting of the City Council of the City of Lake Elsinore,
California, this day of _____________ 20___.
Natasha Johnson
Mayor
Attest:
Candice Alvarez, MMC
City Clerk
CC Reso No. 2023-___
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STATE OF CALIFORNIA )
COUNTY OF RIVERSIDE ) ss.
CITY OF LAKE ELSINORE )
I, Candice Alvarez, MMC, City Clerk of the City of Lake Elsinore, California, do hereby certify that
Resolution No. 2023-____ was adopted by the City Council of the City of Lake Elsinore, California,
at the Regular meeting of ___________ __, 2023 and that the same was adopted by the following
vote:
AYES:
NOES:
ABSENT:
ABSTAIN:
Candice Alvarez, MMC
City Clerk
CITY OF LAKE ELSINORE
MASTER DRAINAGE PLAN UPDATE
(CIP Project No. 120)
Prepared for:
Prepared by:
April 2022
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TABLE OF CONTENTS
SECTION 1 - EXECUTIVE SUMMARY .......................................................................... 1-1
Overview ___________________________________________________________________1-1
Existing MDPs and Drainage Infrastructure______________________________________1-2
Purpose ____________________________________________________________________1-3
Scope of Study ______________________________________________________________1-4
Design Criteria ______________________________________________________________1-5
SECTION 2 - EXISTING FACILITIES AND DRAINAGE ISSUES ................................ 2-9
Flooding and Drainage Issues _________________________________________________2-9
Drainage Issues - General Remedies__________________________________________2-12
Inventory of Existing Drainage Facilities________________________________________2-13
Field Investigation of Existing Drainage Inlet and Outlet __________________________2-15
SECTION 3 - HYDROLOGIC ANALYSIS..................................................................... 3-18
Methodology _______________________________________________________________3-18
MDP Zone Delineation ______________________________________________________3-18
Sub-Drainage Area Delineation _______________________________________________3-20
Land Use & Specific Plans Consistency________________________________________3-20
Hydrologic Soil Group Map___________________________________________________3-22
Debris and Detention Basins _________________________________________________3-23
Flood Plain and Flood Insurance Rate Maps (FIRMs)____________________________3-25
SECTION 4 - PROPOSED MDP FACILITIES AND ALTERNATIVES........................ 4-28
Temescal Wash Zone _______________________________________________________4-28
Alberhill Sub-Zone __________________________________________________________4-35
Lake Zone _________________________________________________________________4-40
East Lake Zone_____________________________________________________________4-48
Existing West Elsinore MDP and ADP _________________________________________4-53
SECTION 5 - ENVIRONMENTAL CONSTRAINTS ..................................................... 5-54
Background________________________________________________________________5-54
Aesthetics _________________________________________________________________5-54
Air Quality _________________________________________________________________5-55
Biological Resources ________________________________________________________5-55
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Cultural Resources__________________________________________________________5-56
Geology and Soils __________________________________________________________5-58
Hydrology and Water Quality _________________________________________________5-58
Wetlands __________________________________________________________________5-59
Other Environmental Considerations __________________________________________5-60
References ________________________________________________________________5-61
SECTION 6 - COST SUMMARY AND FUNDING MECHANISMS.............................. 6-62
Cost Summary _____________________________________________________________6-62
ADP Fees _________________________________________________________________6-65
GIS Data Base _____________________________________________________________6-65
Additional Funding Sources __________________________________________________6-66
SECTION 7 - CONCULSIONS AND RECOMMENDATIONS ..................................... 7-70
Conclusions and Recommendations___________________________________________7-70
Future Growth of the City ____________________________________________________7-70
Limitations _________________________________________________________________7-71
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APPENDIX
APPENDIX A - Field Investigation Report
APPENDIX B – Exhibits
. Grid Map Index
. MDP Facility Grid Maps
. Existing Storm Drain Facilities
. Existing Caltrans Culverts
. Drainage Issue Areas
. Existing MDP Zone Overlay
. Soils Group Map
. City of Lake Elsinore Zoning Map
. MDP Consolidated Zoning Map
. Proposed MDP Zone Exhibit
. Proposed Debris Basins Exhibit
. MDP Zones with MSHCP Criteria Cells and Survey Areas
. MSP Zones with Paleontological Sensitivity
. MDP Zones with Wetlands and “Blue Line” Streams
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SECTION 1 - EXECUTIVE SUMMARY
Strategically located off the I-15 freeway between the Inland Empire and San Diego, the City of
Lake Elsinore is experiencing tremendous growth. With 70% remaining to build-out of its total 42
square miles, the City’s growth and development is expected to continue for the next few decades.
Recognizing the importance of having a well-planned infrastructure system to meet the demands
of an expanding population, the City set the goal of updating its existing Master Drainage Plan
(MDP) into a comprehensive document which will consolidate the existing 51 drainage districts,
incorporate land areas annexed over the last 30 years, and update the existing Area Drainage
Fee schedule. All future development in Lake Elsinore is subject to Area Drainage Fees under
the auspices of Assembly Bill 1600, the Mitigation Fee Act.
Overview
Unique to the City is its namesake, Lake Elsinore, the Lake with the world famous thermal wind.
It is the resource, amenity, and primary attraction of the City, providing a wide range of sport and
recreational opportunities for residents and visitors alike. “Dream Extreme” the City’s logo and
branding slogan, attracts and promotes the sports of sky diving, parasailing, hang-gliding, water
skiing, jet skiing, boat racing, fishing, off-road racing, and such.
The Lake also posts challenges and restrictions to the rapid growth of the City due to excessive
levels of nitrogen and phosphorus (nutrient loading), sediment toxicity, and low water levels
resulting from periodic drought conditions.
Lake Elsinore is at the terminus of the San Jacinto River, within the Santa Ana River watershed.
Lake Elsinore is the largest natural lake in Southern California. It has been in existence for
thousands of years and has historically experienced significant variations in its water level. Today,
the lake receives surface flows from local tributaries, water releases from Canyon Lake, and
recycled water from Elsinore Valley Water District. During rare overflow events, at approximately
1,255 feet water surface elevation (Datum NGVD 1929, Lake Elsinore Outlet Channel designed
by U.S. Army Engineer District Los Angeles, Corps of Engineers), Lake Elsinore overflows into
Temescal Creek and ultimately to the Santa Ana River.
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The City of Lake Elsinore is located approximately 60 miles southeast of Los Angeles and 70
miles north of San Diego, in western Riverside County. The City is bounded by Cities of Canyon
Lake, Menifee and Wildomar to the east, unincorporated areas of Riverside County to the north,
south and west as it lies nestled at the foot of the Cleveland National Forest. Figure 1-1 shows
the general vicinity of the City.
The city terrain ranges in elevation from 1,250 feet at the Lake to a maximum of 2,400 feet above
sea level at southwest corner of the City within the Santa Ana Mountain range.
Figure 1-1
City of Lake Elsinore General Vicinity Map
Existing MDPs and Drainage Infrastructure
The existing city wide Master Drainage Plan (MDP) and Area Drainage Fee (ADF) was approved
and adopted by the City in 1990. This master drainage plan divided the City into 54 drainage
districts with drainage fees assigned for 51 of the 54 districts. The fee schedule associated with
the 1990 MDP was updated by Harris and Associates in 2004, the 2004 updated MDP used the
same hydrology analysis to size the facilities in the 1990 MDP and incorporated much of the same
information from the 1990 MDP.
Within the city boundary and its sphere of influence, there are three MDPs and one Area Drainage
Plan (ADP) prepared and adopted by the Riverside County Flood Control and Water Conservation
District (District). Figure 1-2 depicts the boundaries of these three MDPs.
1. “West Elsinore Master Drainage Plan” and “West Elsinore Area Drainage Plan” were
prepared by Riverside County Flood Control and Water Conservation District (District),
with the Area Drainage Fee approved in 1986 and updated in June 12, 1993. The drainage
area covered by this MDP consists of approximately 10.5 square miles, where nearly 40%
of the drainage area is within the City boundary. Currently, most of the MDP facilities are
constructed, and areas are well developed, except the steep hillside area.
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Figure 1-2
City of Lake Elsinore Existing MDP Exhibit
2. “SEDCO Master Drainage Plan” was prepared by the District in March, 1982. The
drainage area covered by SEDCO MDP consists of approximately 4.5 square miles,
mostly outside the City boundary. However, all SEDCO storm water runoffs discharge to
the Lake through the East Lake area of the City. The SEDCO area and area to the east
were incorporated in 2009 as the City of Wildomar. The City of Wildomar is also in the
process of preparing a city-wide Master Drainage Plan.
3. “Lakeland Village Master Drainage Plan” was prepared by the District and adopted in
March 2015. This MDP study area encompasses approximately 13 square miles, located
south of the Lake, within unincorporated Riverside County. A limited area of the City is
located within this MDP. Since this is one of the latest MDPs prepared by the District, it is
also used as reference for this report.
The above listed three Master Drainage Plans depict three stand-alone watersheds, with runoff
originating from these watersheds flowing into Lake Elsinore. The general areas within these MDP
boundaries are excluded for this study.
Purpose
The primary purpose of updating the Master Drainage Plan (MDP) is to provide a comprehensive
storm water strategy that provides flood protection for both existing and future developments
within the City.
The MDP will also: identify the drainage facilities to address the major drainage problems within
the City; establish the estimated costs of those facilities, and identify the funding sources for the
city-wide flood control and drainage infrastructure, to facilitate safe, orderly and economically
development of the area. In addition, this study will also explore the opportunity for implementing
watershed-based BMPs, and water quality mitigation and treatment with the focus on nutrient
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reduction, to enhance the beneficial use of, and minimize the negative impact to the Lake water
quality from current and future development.
This MDP update study addresses the current and future drainage needs of the communities
within the City. The boundary of each drainage zone follows regional watershed limits. The
proposed facilities include channels, storm drains, debris and detention basins, and any other
conveyance capable of economically relieving flooding problems within the City. The plan
includes an estimate of facility capacity, sizes and costs.
In addition to providing a guide for the orderly development of the City, the MDP update also
provides an estimate of costs to resolve flooding issues within each drainage zone or sub-zone.
Those costs will be used to establish Area Drainage Fees exacted under AB 1600, which prevent
existing taxpayers from having to shoulder the burden of land development costs.
The alignment and location of the facilities proposed in this MDP update are conceptual. Precise
locations and size of the facility will be dictated by site specific conditions and other factors such
as environmental, engineering and economic considerations.
Scope of Study
The updated MDP study consolidates the drainage districts, assesses and inventories the existing
drainage infrastructures, incorporates updated city boundary, general plan land use, and rainfall
data, and produces a comprehensive master drainage plan for the entire city. The drainage fee
schedule will correspond to the consolidated drainage zones. West Elsinore ADP fees will be
adjusted using the published construction cost price index value by Engineering News Record,
widely known as ENR.
In conjunction with this study, GIS data layers have been developed for MDP facilities, drainage
zone boundaries, and the area drainage fee schedule to integrate into the City GIS data base.
The overall scope of the MDP update included the following:
o Existing drainage facility data collection and field investigation of the flooded areas and
conditions of inlets and outlets of major storm drains
o Establishing basic engineering design criteria and consolidating existing 51-Drainage
Districts to 4-MDP Zones for drainage and flood control within the City
o Compiling existing available topography and land use plans for the project area
o Preparing hydrology analysis for the study area of the City and its tributary areas
o Identifying proposed drainage improvements for each MDP zone or sub-zone
o Investigation of alternatives for the proposed drainage facilities and cost estimates
o Finalizing MDP facility and Area Drainage Fee for each zone or subzone
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Design Criteria
It is imperative to establish the criteria for the Hydrology and Hydraulics (H&H) study and MDP
design guideline before proceeding with the detailed studies and design. Webb has reviewed the
existing MDPs within or near the city boundary prepared by Riverside County Flood Control
District (District) to ensure the City of Lake Elsinore MDP will be compatible and consistent with
the surrounding areas. The following criteria were discussed with the Interim City Engineer, and
were reviewed and approved by the City.
1. Hydrology
The hydrology for this MDP will be developed using two methods: the Rational Method and the
Synthetic Unit Hydrograph Method. The Rational Method will be used to determine the peak
discharges (cubic feet per second) generated from watersheds smaller than 300 to 500 acres in
size. For watersheds larger than 300 to 500 acres, primarily the watersheds outside the city
boundary and steep hilly areas, the Synthetic Unit Hydrograph Method will be used. Methodology
and supportive data for both Rational and Synthetic hydrology, including estimation of loss
rates/infiltration, may be found in the Riverside County Flood Control and Water Conservation
District Hydrology Manual, dated April 1978 (District Hydrology Manual).
2. Land Use
In 2011, the City completed an update of its General Plan. For the watershed areas within the city
boundary, land use designations from the updated General Plan will be used to develop the
hydrology for this MDP.
For the watershed areas outside the city boundary, the 2003 Riverside County General Plan land
use designations will be used.
In addition to the City and County General Plan land use, there are 17 Specific Plans within the
city, and each has its own land use designations. Some of these Specific Plans are almost built-
out, while others are still evolving and going through amendments.
Due to the dynamic and complex nature of the land use designations and their actual impacts to
the hydrology studies, we propose to consolidate the land use into 7 categories with assigned
impervious percentage recommended per the District Hydrology Manual. For Specific Plans, if
there are 10 planning areas with varied density, an average total may be used for MDP level of
the studies. This approach will simplify the process without compromising the integrity of the
study.
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City of Lake Elsinore MDP Land Use Summary
Land Use
Group
RCFCD Hyd Manual ImperviousLand Use per General Plan RemarksCover Type Cover
Open
Space
OS-Open Space, F-Floodway, Conservation Natural (Fair)5%Lakeland Village
MDP used (Good)
cover for the
same land use
group.
Bank, RMR-Rural Mountainous
Residential, RR-Rural Residential
Chaparral
Broadleaf
Park &
Rec
Park, L-Lakeshore, R-Recreation, Golf
Course
Urban Landscaping
1 Acre Lots
15%
30%
40%
VLDR Very Low Density Residential, Estate
Density Residential
LDR PI-Public Institutional, Schools, LDR-Low
Density Residential
1/2 Acre Lots Use >40% based
on actual
impervious cover
MDR
HDR
R1-Single Family Residential, R2-Medium
Density Residential, LMD-Low Medium
Density Residential, MD-Medium Density
Residential, MHD-Medium High Density
Residential
1/4 Acre Lots 50%
High Density Residential, RMU-Residential Condo,
Mixed Use, MC-Mobile Home community, Apartments,
EC-Existing Condo, EMH-Existing Mobile
Home Complex
75%
90%
Mobile Home Park
Commer- Varies Commercial C1, C2, CM, CO, CP, CR, Commercial,
cial NC, TC, GC, Manufacturing M1, M2, M3,
BP-Business Professional, LI-Light
Industrial
Downtown
Business or
Industrial
3. Rainfall Values
To be consistent with the recently completed Lakeland Village MDP prepared by the District, the
NOAA Atlas 14 rainfall data will be used in the hydrology calculations for this MDP. The rainfall
frequencies examined are the 2-year (50% annual chance) and the 100-year (1% annual chance)
recurrence intervals with 1, 3, 6 and 24 hour durations. The calculated slope of the intensity-
duration curve is 0.6. The following NOAA Atlas 14 Version 4 average point rainfall values will be
used to develop the hydrology:
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NOAA Atlas 14 Point Rainfall Values
Storm Frequency and Duration Average Point Rainfall (Inches)
2 Year – 1 Hour 0.48
2 Year – 3 Hour 0.86
1.24
2.34
1.34
2.17
3.06
6.29
2 Year – 6 Hour
2 Year – 24 Hour
100 Year – 1 Hour
100 Year – 3 Hour
100 Year – 6 Hour
100 Year – 24 Hour
4. MDP Facilities
Currently, the existing storm drain facilities within the city limits are maintained by various entities
and agencies; including RCFCD, Caltrans, City of Lake Elsinore, City of Wildomar, County of
Riverside Transportation Department, HOAs and others. To streamline the future design,
maintenance, and funding, the City may consider establishing some guidelines and maintenance
mechanisms (CFDs or Assessment Districts) and the discussion of those is included in the MDP
documents. Each maintenance entity also dictates the design standards. For the purpose of MDP
facility design and cost estimate, RCFCD standards and design guidelines will be used.
Underground Storm Drain System
All of the underground storm drain systems will be designed to convey the runoff from a 100-year
storm, with RCP sized 36” and larger. Road culverts, laterals and collectors will not be identified
as MDP facilities. The underground facilities proposed in this MDP will be located within existing
or assumed future right-of-way, whenever possible. The typical MDP storm drain pipe or box
design will have 3’ of cover with the slopes parallel to the existing ground.
Open Channels
Well defined natural channels, canyons and ravines are the most economical way to transport
and convey the storm runoff, and pose the least impacts to potentially sensitive areas. The MDP
study will focus on preserving and maximizing the utilization of natural water courses.
When natural water courses become less defined, flattened and spread out, they may cause
flooding of the roadway and properties, as well as add constrains to future development. Open
channels may be used to continue transporting storm runoff to a safe outlet. The open channels
not only serve as flow conveyors, they also provide an outlet for underground facilities. This MDP
study will utilize two types of open channels, lined and unlined. Lined channels will be used in
high velocity flow situations and are typically rectangular or trapezoidal shaped with concrete
paving on the sides and bottom. Unlined channels will be utilized in low velocity flow situations,
are typically trapezoidal in shape and have no protection for the bottom or side slopes. The
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unlined channels can also provide infiltration or filtration opportunities for water quality
management.
The channel right-of-way required for both lined and unlined facilities must accommodate the full
channel width along with adequate maintenance access. Channels with top widths less than 20
feet require one maintenance access road, and where the top width exceeds 20 feet, two
maintenance access roads are necessary per RCFCD design standards. All of the open channels
will be designed to convey the runoff from a 100-year storm.
Detention Basin
Detention basins maybe utilized for this MDP. The purpose of the detention basin is to lower the
peak flow rate through the use of temporary detention storage, thus reducing the size and cost of
the downstream MDP facilities. It should be noted that a detention basin, if proposed, will be sized
for the 1% annual chance ("100-year" storm) event. Flows exceeding the design capacity of the
basin would pass over the emergency spillway or overflow structure, discharge into the
downstream storm drain pipe or open channel. A detention basin may also be used when existing
downstream facilities have inadequate capacity.
Debris Basins
Debris basins may be used in watersheds that are equal to or greater than 64 acres and are
generally located upstream of the proposed facilities to capture debris before it enters the
downstream conveyance system. The proposed debris basins will be sized based on the Los
Angeles District Method for Prediction of Debris Yield (Method) developed by the U.S. Army Corps
of Engineers Los Angeles District, dated February 2000. The Method is intended to be used for
the estimation of debris yield in watersheds of 64 to 128,000 acres in areas with steep,
mountainous terrain. The MDP study will further evaluate the benefits of reducing sedimentation
and debris, reducing facility size (without using bulked flowrate) and ease of maintenance versus
the cost of land acquisition and cost of construction of the debris basins.
Recharge Basins
An evaluation for use of recharge basins was made as part of the MDP. Due to the highest and
best use assigned to runoff to the Lake and the basin size required to be cost effective,
locations were not selected at this time. Recharge Basins can and will be considered as
construction of MDP facilities occurs.
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SECTION 2 - EXISTING FACILITIES AND DRAINAGE ISSUES
Drainage issues include street and private property flooding, erosion, long-term ponding, drainage
facility maintenance issues, and hillside runoff. The drainage facilities include City-owned storm
drains and channels, Riverside County Flood Control District-owned and maintained storm drains
and channels, homeowner association-owned basins, and the inlets and outlets associated with
each. The field surveys and documentation provided in this report were collected from January to
March 2015.
Most of the drainage issue locations and drainage facility locations were identified by City staff
prior to the field surveys. The drainage issue locations were collected by City maintenance and
engineering staff based on past resident complaints and prior knowledge and experience in the
area. The type and location of various existing storm drain facilities are based on as-built plans in
the City’s possession. The locations were input into an electronic map using GIS software to keep
collected information geo-referenced and easily accessible. During the field surveys, all notes and
pictures were collected using the ArcGIS Collector mobile application. This application operates
on any mobile phone or data-enabled tablet and uploads information to the GIS map in real-time.
All of the field surveys were conducted by at least one engineering staff member from Albert A.
Webb Associates (Webb) along with at least one engineering staff member from the City.
Flooding and Drainage Issues
With the assistance of the City Maintenance and Operation staffs, Webb surveyed and
documented approximately 79 drainage issue locations. These locations are characterized by any
combination of street flooding, private property flooding, dirt or roadway erosion, long-term
ponding, hillside runoff, and maintenance issues. Nearly all of the drainage issue locations are
located between Interstate 15 and the northeast side of the lake. The northeast side of the City is
largely an older area with few to no existing storm drain facilities. There are also several steep
slopes in the area that seem to exacerbate the flooding and runoff problems.
Below are the top ten flooding locations in the City provided by the city staff:
1. 1209 N. Sumner
2. 3rd Street / Pasadena
3. Avenue 6 / Lakeshore
4. Pepper / Dawes
5. Mission Trail south of Olive.
6. High St / Alley e/o Lakeshore
7. East side of Lakeshore from Morton to 100 feet past Lake Park Street
8. Lakeshore / Kansas on north side of Lakeshore
9. W/S Machado s/o Joy St by guard rail
10. Franklin by Cell Tower
Figure 2-1 shows the locations of observed drainage issues throughout the City.
A summary table with the locations of the City wide drainage issues and recommended mitigation
measures are provided at the end of this section.
2-9
Figure 2-1
City of Lake Elsinore Drainage Issue Locations
o Street Flooding. Street flooding in the City is primarily caused by low points in or near
the street without proper drainage facilities. Although the climate is relatively arid, water
often remains in the street for days and even weeks after a rain event. This is especially
true on gravel roads and on streets with low points in or near dirt shoulders.
Roadway flooding on Collier Ave. near Chaney Street Roadway flooding on Lakeshore Drive at Matich Street
2-10
o Private Property Flooding. Private property flooding and water damage in the City
mainly occurs near hills and in areas of low elevations. Water often flows down hills or
streets and runs through or ponds in private property. This kind of flooding usually occurs
when property is at lower elevations than the street or when the street is lacking curbs or
berms to properly channelize the water. Often gravel bags were placed along the street
edge of pavement or property line by the City M&O staff to reduce the flooding.
Street flow on Ellis Street drains down slope into property at
Lower elevation
Sand bags at Country Club Dr. and Acacia Street
o Erosion. Street shoulder erosion is most commonly found on streets with no curb or berm
to properly channelize water. Storm runoff flows in the dirt at the edge of the street creating
ravines. The runoff can get underneath the street and cause pavement damage. Erosion
is also found wherever an undeveloped hillside meets a street. Dirt and debris from the hill
are carried by the water and are deposited on downstream streets and property.
Dirt shoulder erosion adjacent to pavement on Franklin Street Hillside erosion
o Maintenance Issues. There are many locations that the City’s maintenance staff handles
on a regular basis. The staff places sandbags in runoff areas near hills, vacuums
problematic ponding areas, and clears runoff debris from streets and blocked storm drains.
Maintenance of drainage areas is constant. Storm drains are routinely blocked after a rain
event with heavy deposits of dirt and debris.
Storm drain outlets blocked with dirt on Pierce and Collier Avenue
2-11
Drainage Issues - General Remedies
Most of the drainage issues occur from only a few causes. The most common causes of the
surveyed drainage issues are low points on the street or property, lack of curbs and/or gutter
facilities, unimproved hillside, and insufficient maintenance of existing facilities.
Street flooding is often caused by streets not having proper slopes and crowns, and lack of
dewatering measures at low points. Some streets in the City were found to have low points within
the traveled way. The slopes of the pavement can be improved by paving, but care should be
taken to not simply put the water on the shoulder of the road. Water can often pond or erode dirt
shoulders if not properly channelized.
The City uses a mix of asphalt concrete berm, curb, and curb/gutter combinations throughout the
City to help channelize water that runs off of the street. However, many locations simply have dirt
shoulders without any curb or gutter facility. This leads to ponding, dirt erosion, and dirt runoff.
Constructing berms, curbs, and gutters can help channelize the water along the street and
towards storm drain facilities.
There are many vacant and unimproved lots and areas throughout the City imbedded in the older
neighborhood, and often leave gaps in curbs, gutters and sidewalks. The storm runoff from these
lots often brings dirt and debris to the street and causes erosion and blocks the street flow. The
City has been placing sandbags to keep the storm runoff flowing within the street, as a temporary
solution. More permanent solutions such as berms, curbs, and gutters can be added to the
frontage of these lots to assist in drainage. Also, the addition and preservation of vegetation and
other plants can reduce the amount of water runoff and dirt erosion from these areas. A special
assessment fee or NPDES requirements for the vacant lots may be considered for funding of the
maintenance.
It is clear that the majority locations with flooding and drainage issues are in older neighborhoods
of the City, areas with very few to no existing storm drain facilities. A few areas with the erosion
and flooding issues can be addressed by installing asphalt berm or concrete curb and gutter along
the existing edge of pavement, a low cost solution. For the majority of the areas with flooding
issues, the long term solution is to establish a system of drainage facilities to safely convey storm
runoff to the Lake or other receiving water.
2-12
Inventory of Existing Drainage Facilities
The existing storm drain facilities within the City boundary and MDP study area can be separated
to three major categories based on the maintenance responsibility:
Figure 2-2
City of Lake Elsinore Existing Drainage Facilities
1. City and privately owned and maintained facilities – the City completed a City-wide GIS
mapping in July of 2013. The City facilities range from underground pipe systems and
concrete lined channels, to culverts and basins. Some of the water quality basins and
detention basins may be maintained by the HOAs or POAs. Some of the facilities shown on
the City GIS map database may be duplications of the District’s facilities (in the West Elsinore
MDP area).
2. The District (RCFCD) owned and maintained facilities – The MDP study area is located in
the District’s Zone 3. There are 47 sets of “As Built” RCFCD storm drain plans collected and
reviewed for this study. These “As Built” plans dated as early as 1954, the latest addition is
Arroyo Del Toro Channel plans dated 2013. Among the District facilities, Outlet Channel is a
unique facility designed by the Army Corp of Engineers. With its crest (high point) located at
mid Wasson Canyon Channel inlet, it conveys half of the Wasson Canyon runoff to the Lake
in normal storm events. It also discharges Lake’s overflow to the Temescal Wash when 1255
water surface elevation is reached in the Lake. A summary of the District’s facilities is provided
hereon for reference.
2-13
Existing RCFCD Facilities
No.Project No. Dwg No.Facility Name Reach
Lake to Grand Ave.
Type
U Channel13-0-00010 3-063
3-0-00008 3-068
3-0-00100 3-070
3-0-00030 3-078
3-0-00030 3-078
3-0-00060 3-079
3-0-00030 3-085
3-0-00060 3-092
3-0-00090 3-093
3-0-00090 3-100
3-0-00070 3-102
3-0-00100 3-106
3-0-00100 3-109
3-0-00120 3-110
3-0-00100 3-112
3-0-00120 3-116
3-0-00140 3-119
3-0-00175 3-126
3-0-00180 3-127
3-0-00149 3-128
3-0-00070 3-129
3-0-00070 3-130
3-0-00040 3-131
3-0-00071 3-133
3-0-00005 3-135
3-0-00004 3-135R
3-0-00216 3-141
3-0-00148 3-142
3-0-00071 3-143
3-0-00220 3-146
3-0-00100 3-147
3-0-00100 3-149
3-0-00100 3-158
3-0-00226 3-159
3-0-00004 3-162
3-0-00071 3-171
3-0-00120 3-178
3-0-00220 3-179
3-0-00145 3-180
3-0-00220 3-185
3-0-00045 3-186
3-0-00085 3-187
3-0-00085 3-190
3-0-00141 3-191
3-0-00040 3-194
3-0-00086 3-195
3-0-00170 3-196
Lakeland Village Storm Drain
Churchill Street Ditch2 Turnaround to Grand Ditch
3 Leach Canyon Debris Dam
Lime St. Channel Stage I & II
Lime St. Channel Stage I & II
Stoneman St. Channel
Right of Way Map, Debris Dam
Hill Street
Dam
4 Trap Channel
Trap5Lake to Laguna Ave
6 Stoneman at Grand Trap
7 Lime St. Channel Stage III
Stoneman St. Channel Stage II
South riverside Channel Stage I
South riverside Channel Stage II
Ortega Channel Stage I
Laguna to Grandview Trap
8 Stoneman St Channel
Trap9Lake Elsinore to Laguna Ave.
Washington to Dreycott on Laguna
Lake to Grand Ave.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
RCP
Trap
Leach Canyon Channel Stage I
Leach Canyon Channel Stage II
Four Corners Storm Drain Stage I
Leach Canyon Channel Stage I
Four Corners Storm Drain Stage III
SEDCO Line D & D-1
Lake 3+40 to 33+50 Conc. Trap
Conc. Channel
RCP
Machado to Riverside
Lake to Riverside Dr.
Restoration Conc Channel
RCPOn Lakeshore Dr. to Gunnerson
Mission Trail to I-15 RCP
Third Street Channel Thrid St and Collier Ave Trap, RCB
Basin, RCP, channel
U Channel, 60" RCP
RCP
Wasson Canyon Channel Stage I
SEDCO Line F-2
Minthorn Street and Collier Ave
Along Tract 23235 boundary
Grand to Ortega HwyOrtega Channel Stage II-A
Ortega Channel Stage III Tr 19358 Channel & RCP
RCP or CIPP
RCP
SEDCO Line F-3 North of Strickland Av to South of Collier Ave
Tract 20139-1Ortega Channel Laterals A & A1
Lake Elsinore Outlet Channel
Lake Elsinore Outlet Channel-Rt 74
W Elsinore MDP Line A-1
SEDCO Line F-4
Sheets R1-R50 Mics, Waterline relocations
Channel Bridge -Caltrans Riverside Dr
Tr 28748 & 28748-1 / Stage 1 on Grand Ave
Tr 23295 - Gafford Road & Winding Way
On Grandview and Lakeridge
Tr 30789 Stage 2, Sandpiper Drive
CFD 88-3, Line B, Stage 3 & Line B-1, Stage 1
CFD 88-3, McVicker Channel Line B-1, Stage 2
CFD 88-3, Line B-1, Stage 3
CFD 88-3 Debris Basin, Line B-1 Stage 4
Lake Elsinore to Temescal Creek
Welford Place
Bridge
RCP
RCP, Channel
RCPOrtega Channel Stage II
W Elsinore MDP Line C RCP
Leach Canyon Channel Trap Channel
Trap Channel
Channel, RCP
Basin, Channel
Trap Channel
Basin
Leach Canyon Channel
Leach Canyon Channel
W Elsinore MDP McVicker Debris Basin
Lake Elsinore Outlet Channel-USACE
Ortega Channel Lat-A Debris Basin
Four Corners Storm Drain
W Elsinore MDP Line C & C1
SEDCO Line E
Stage 4, Lakeshore Drive RCP
Tract 30789, Line C Stage 2
Park Access to Mission Trail
Tract 31917, Line C Stage 3
Channel Bridge -Caltrans Riverside Dr
Stage 1 From Collier Marsh to I-15
Tract 29513
RCP, Basin
RCP, Channel
RCP, Basin
Channel & RCB
RCP
W Elsinore MDP Line C & C1
Palomar and Corydon Channel
SEDCO Bryant St Storm Drain
SEDCO Bryant St Storm Drain
SEDCO Line F
RCP, Basin
60" 72"-RCP
Pond
Stage 2, from Elsinore HS to I-15
Gunnerson Pond Restoration, landscape
Tract 31345
Gunnerson Pond - USACE
SEDCO Beech Dr. Storm Drain
Arroyo Del Toro Channel
RCP, Basin
RCB & U-ChannelStage 1 From Collier Marsh to I-15
2-14
3. Caltrans facilities – Integrated with the construction of I-15 Freeway in 1980, many drainage
culverts were constructed within the State R/W, to allow the storm runoff crossing under I-15
along the existing drainage courses as well as provide for de-watering of the highway. The
“As Built” storm drain plans were obtained from Caltrans and examined. The drainage facilities
shown on the “As Built” plans were compiled and depicted on the Existing Drainage Facilities
shown on Figure 2-2 and Caltrans Culverts on Figure 2-3. These culverts are maintained by
Caltrans. Typically, neither culvert design capacity nor hydraulics data are depicted on the “as
built” plans. For any extension, connection or modifications of these culverts, a Caltrans
encroachment permit will need to be obtained.
Figure 2-3
Existing Caltrans Culverts
Field Investigation of Existing Drainage Inlet and Outlet
A survey of the documented existing storm drain inlets and outlets larger than 36” in diameter was
conducted. Some of the inlets and outlets surveyed had various degrees of blockage due to
sediment, debris, foliage, or a combination of the three. An effort should be made to clear all of
the blocked inlets and outlets. In addition, regularly scheduled maintenance of the facilities is
required in order to keep the facilities operating as intended.
With the assistance of the City O & M staff, Webb surveyed and documented approximately 109
inlet or outlet locations throughout the City to verify size, location, and condition of each. Included
2-15
in the survey are large culverts, weirs, inlets and outlets in basins, and storm drain channels.
Regarding inlets and outlets, Webb only surveyed pipes 36” inches in diameter or larger to limit
the field review to MDP mainlines and large pipes. The inlets and outlets were found throughout
the developed areas of the City. Figure 2-4 shows the locations of surveyed inlets and outlets
within the City.
Figure 2-4
City of Lake Elsinore Storm Drain Inlet and Outlet Locations
The existing drainage facilities include City-owned storm drains and channels; Riverside County
Flood Control District-owned underground storm drains, open channels and debris basins;
homeowner or property owner association-owned and maintained basins, and the inlets and
outlets associated with each. An in depth, detailed Field Investigation Report is provided in
Appendix A of this report.
Outlet Headwall in the Links at Summerly Golf Course Box Culvert under Collier Avenue
2-16
Based on the field survey and observation, we recommend that the following measures be
considered for drainage facility maintenance:
•Establish an annual major drainage facility clean up schedule, preferably completed
before the starting of the rainy season, once a year minimum
Allocate funding and manpower for major cleanup and debris removal
Organize local communities, volunteer groups, and school districts to participate in the
cleanup
•
•
•
•
•
Combine the cleanup with public outreach and public education for “Keep Our Lake
Clean”, “Only Rain in the Lake” and such
Keep a record of sediment and debris removal load and frequency at the major inlets
and outlets
Identify the sources and evaluate any additional measures which can be implemented to
reduce the sediment and debris load
2-17
SECTION 3 - HYDROLOGIC ANALYSIS
Methodology
The hydrologic analysis for the study area was performed using methodology consistent with the
guidelines in the Riverside County Flood Control and Water Conservation District Hydrology
Manual. The Modified Rational Method and Synthetic Unit Hydrograph Method were used to
establish the peak discharge rates. The methodology for the hydrologic analysis is also discussed
in Design Criteria of SECTION 1 of this report, and approved by the Interim City Engineer prior to
commencing the hydrology study.
MDP Zone Delineation
Based on the initial data collection, analysis, regional drainage boundaries from the prior master
drainage plans prepared by the District and input from the City, the following parameters for the
MDP update and zone delineation were established:
o East Lake area is a special development focus zone of the City, with the continuation of
East Lake Specific Plan Amendments, and priority set by the City, this area shall have an
independent study.
o Sedco area is outside the City boundary with an existing District MDP, its runoff drains
into the Lake through the East Lake area. The City of Wildomar is currently preparing a
city-wide MDP, which incorporates the Sedco area. The results of Wildomar’s MDP study
data is be utilized for the East Lake drainage design.
o West Elsinore area is guided by the District’s West Elsinore MDP, and its drainage facilities
are 80 to 90% constructed. No new study is required.
o The District completed and adopted Lakeland Village MDP in March, 2015. Lakeland
Village area will be excluded from this study.
o The areas outside the City limit will not be studied unless the areas are in the watersheds
directly draining into the City.
Webb also reviewed and examined the existing MDP Map and fee schedule. Fourteen (14) of the
total 51 MDP districts are either completely or mostly outside the City boundary; the City has no
jurisdiction to collect Area Drainage Fees from these unincorporated areas or within the City of
Wildomar.
In addition to the above-listed considerations, we established three proposed MDP Zones under
the direction of the City Engineer. The division of the new zones is primarily based on the receiving
water. The storm runoffs from the East Lake and the Lake Zone are directly discharged into the
Lake, as is the runoff from existing West Elsinore MDP and Lakeland Village MDP. Temescal
Wash is the receiving water for the Temescal Wash Zone.
The overlay of the existing MDP Map and Proposed MDP Zones is shown on Figure 3-1 below.
The proposed MDP Exhibit is shown on Figure 3-2.
3-18
Figure 3-1
Existing City MDP Map Overlay
Figure 3-2
Proposed MDP Zones
3-19
Sub-Drainage Area Delineation
The delineation of the sub-drainage area is based on the natural flow patterns, ridge lines,
developed conditions and available data for the proposed developments.
For the areas outside any filed Specific Plans and Tentative Maps, natural drainage patterns were
used for hydrology study.
For the existing master planned communities, such as Canyon Hills, Tuscany Hills, Canyon
Creek, La Laguna Estates, etc. no additional studies are performed since the drainage facilities
in these communities are either fully or partially build out.
For the areas within the Tentative Tract Map or Specific Plan Studies, the proposed storm drain
facilities are obtained from the design engineer when available, and incorporated in the MDP
accordingly.
Land Use & Specific Plans Consistency
As established in Design Criteria of Section 1 of this report, the General Plan Land Use needs to
be consolidated and reclassified based on the imperviousness for hydrology study.
Figure 3-3
2012 General Plan Land Use Map
3-20
Within the city boundary there are 17 adopted Specific Plans. Land uses for these Specific Plans
were not depicted on the Land Use Map as shown in Figure 3-3. Some of the Approved Specific
Plans have been amended many times. East Lake Specific Plan has been amended 10 times,
and is in the process of additional modifications.
It is anticipated that the future development trend, market demand, and environmental regulations
will result in many additional amendments. New Specific Plans will also bring changes in land
use. It is understood that the city-wide land use map is a dynamic, ever changing document. For
the hydrology study, the exactness of the land use is less prevalent than imperviousness derived
from the land use.
Webb compiled a comprehensive land use map to cover the MDP study areas (see Figure 3-4).
The land uses from following Specific Plans were reviewed and incorporated in this overall land
use map.
City of Lake Elsinore Specific Plan Summary
LocationSpecific Plan Name
Alberhill Ranch
Amd No Date MDP Receiving Water
Temescal Wash
Proposed MDP Zone Stage
Undev
to Lake
NW#3 1997 Alberhill Sub-Zone
Alberhill Sub-Zone
Lake
Murdock Alberhill Ranch #2
#3
2008
2005
NW
NE
Temescal Wash
San Jacinto River
Phase 1 Dev
UndevCanyon Creek (La Strada) N
Canyon Creek (La Strada) S
Canyon Hills (cottonwood
Hills)
#3
#3
2005
2009
NE San Jacinto River
San Jacinto River
Lake
Lake
In Construction
Partial DevEast
Canyon (Hills) Estates
Cape of Good Hope
Cottage Lane
2006
1993
2005
2010
2013
East
NW
San Jacinto River Lake Undev
UndevLake / Temescal Wash Temescal Wash
West
East
East
Lake
Lake
Lake
West Elsinore MDP Partial Dev
Diamond #1 East Lake
East Lake
Partial Dev
Partial DevEast Lake #10
Elsinore City Center
Lake Elsinore Outlet Center
Lakeshore Village
La Laguna Estates
North Peak
2001
2000
2003
2003
1999
East San Jacinto River
Temescal Wash
Lake
Lake Complete
#3 North
West
West
North
Temescal Wash Mostly Develop
West Elsinore MDP Mostly Develop
West Elsinore MDP Complete#1
#2
Lake
Lake / Temescal Wash Lake / Temescal
Wash
Undev
Ramsgate #6 2008 North Lake / Temescal Wash Lake / Temescal
Wash
Partial Dev
UndevSpyglass Ranch 2008
2006
1990
North
West
NE
Lake Lake
The Village at Lakeshore
Tuscany Hills
Lake West Elsinore MDP Undev
#1 San Jacinto River/
Canyon Lake
Lake / Temescal Wash
Lake South side Dev
Terracina 2014
2015
NW
NW
Lake / Temescal
Wash
In Review
In ReviewAlberhill Villages Temescal Wash Alberhill Sub-Zone
3-21
Figure 3-4
Land Use Map for Hydrology Study
Hydrologic Soil Group Map
Another major factor affecting infiltration and peak storm runoff is the nature of the soil. Soil types
for this study were taken from the hydrologic soils classification maps in the Hydrology Manual of
the District. An overall hydrologic soil group map is compiled for the study areas as shown in
Figure 3-5.
The four main hydrologic soils groups developed by the Soil Conservation Service of the U. S.
Department of Agriculture were utilized by the District to classify soils types. Soils Group A has
low runoff potential and high infiltration rates with mostly sandy soils. On the other end of the
spectrum, Soils Group D has high runoff potential, very slow infiltration rates, consists of mostly
clay soils and is nearly impervious. As shown in Figure 3-5, the majority of the study areas consist
of Groups C and D soils. Generally speaking these types of soils are not suitable for infiltration
and ground water recharging.
3-22
Figure 3-5
Hydrologic Soil Groups Map
Debris and Detention Basins
Debris Basins
The estimation of debris yield from an erosive upland watershed is an important factor in the
design and maintenance of debris basin and flood control projects. Nine debris basins have been
proposed to capture sediment and debris before it enters the proposed storm drain facilities (see
Figure 3-6 Proposed Debris Basins). The 100-year single event debris yield estimates were
determined at the canyon mouths of Subareas A1 and A2, A4-2, A6, A7-1, A10, A11, A4-2, and
A5-1 using the LADCOE Debris Method. The delineation of these subareas is also shown on
Figure 3-6.
Sediment production from a watershed is a function of several variables. The most evident
variables are vegetative cover, rainfall intensity, slopes of the watershed, geology, soil type, and
size of the drainage area. Fire greatly increases the amount of runoff and erosion from a mountain
watershed caused by lack of vegetation and lowered infiltration rates. The inclusion of sediment
in runoff results in a greater total discharge which is referred to as bulking. Sediment discharge
from a major storm can be equal to the actual storm runoff, that is, runoff bulked 100 percent. If
debris basins were not proposed for these areas, the downstream facilities would need to be sized
3-23
for the bulked flows and routinely maintained (cleanout) to ensure that the design capacity is
conveyed at all times. Due to the enclosed nature of the underground storm drains and difficulty
in removing the sediments, the sediment removal costs would be far more costly than debris basin
cleanout costs.
Figure 3-6
Proposed Debris Basins
Flood history in Southern California clearly demonstrates the debris yield hazard as one
associated with singular storm events, and has shown that over 80% of the annual volume of
sediment comes from a single storm event. Therefore, the debris basins proposed in this MDP
are designed for a single event as opposed to a long term (average annual) volume basin.
Because the proposed structures are sized to only intercept debris from a single flood event (100-
year frequency), the captured debris would need to be removed from the basins to ensure
adequate storage capacity for subsequent storm events.
The proposed debris basins were sized based on the Los Angeles District Method for Prediction
of Debris Yield by the U.S. Army Corps of Engineers Los Angeles District (LADCOE), dated
February 2000. The Method provides a systematic approach for determining the debris yield from
a single flood event to be used in the debris basin design sizing. Debris basins were sized for the
100-year event storm using the 100-year 1-hour rainfall data. Due to the lack of site specific data,
the most conservative fire factor (FF) of 6.5 was used (corresponding to less than one year after
100% watershed burn). For areas outside (San Gabriel Mountains) of which the equations are
based, application of the Adjustment-Transposition (A-T) Factor must be carefully determined. To
preclude any subjectivity of this very sensitive parameter and to produce conservative results, an
3-24
A-T factor 1.0 was used. Typically a factor of safety is needed because of the uncertainty in the
estimation of certain parameters (A-T and FF factors), but the most conservative values were
used, therefore no factor of safety was applied to produce the storage volume needed for the
sizing of the basins. Results of the analysis are presented in table below.
100−Year Single Event Debris Yield Summary
100−Year
Peak
Stream Elevation
Unit Peak Length Difference Ratio
Relief Debris
Yield
DebrisDrainage AreaDebris
Basin
1−Hour Fire Log
DY
A−T Volume
Rainfall Discharge Runoff Factor(d)Factor(ac)(mi2)(mi)(ft)(ft/mi)(yd3 /mi2)(yd3)(in)(cfs)(cfs/mi2)
Equation (a)
DB1
DB2
DB10
DB9
DB9A
DB5
DB8
949.2
1425.4
131.0
1838.0
293.0
822.0
362.4
1.48
2.23
0.20
2.87
0.46
1.28
0.57
1.34
1.34
1.34
1.34
1.34
1.34
1.34
−
−
−
−
−
−
−
−
−
−
−
−
−
−
3.803
3.845
0.873
4.360
1.307
2.519
1.597
1507 396.2
303.2
350.7
634.3
713.1
264.7
765.2
6.5
6.5
6.5
6.5
6.5
6.5
6.5
4.31
4.27
4.12
4.49
4.38
4.19
4.41
1.0
1.0
1.0
1.0
1.0
1.0
1.0
20,382
18,578
13,229
30,734
23,747
15,466
25,776
30,165
41,429
2,646
1166
306
2765
932
88,207
10,924
19,796
14,692
667
1222
Equation (b)
8.16 1024DB6(c)
Note:
5133 8.02 −3394.6 423.3 125.5 4.0 4.19 0.65 15,355 123,147
(a) LADCOE Equation 1: Log DY = 0.65(Log P) + 0.62(Log RR) + 0.18(Log A) + 0.12 (FF), for watersheds 0.1 to 3.0 mi2 in size
(b) LADCOE Equation 2: Log DY = 0.85(Log Q) + 0.53(Log RR) + 0.22 (FF) + 0.4 (Log A), for watershed 3.0 mi
(c) An A−T Factor 0.65 was applied due to larger watershed size
2 to 10 mi2 in size
(d) An assumed condition of less than one year after 100% burn, except for DB6 which assumes only 2/3 of the watershed is susceptible to burn
Detention Basins
The purpose of detention basins proposed in this plan is to reduce peak flow rates in the
downstream storm drain system through the use of temporary detention storage. This peak flow
reduction allows the use of smaller, less costly downstream facilities. A combination
detention/debris basin (DB 11) is proposed for the upper portion of the Tuscany Hills Specific
Area.
Flood Plain and Flood Insurance Rate Maps (FIRMs)
The following Flood Insurance Rate Maps (FIRMs) are within the City of Lake Elsinore.
1. 06065C2681G
2. 06065C2034G
3. 06065C2033G
4. 06065C2016G
5. 06065C2006G
6. 06065C2008G
7. 06065C2019G
8. 06065C2038G
9. 06065C2039G
10. 06065C2043G
11. 06065C2042G
12. 06065C2061G
13. 06065C2041G
14. 06065C2037G
15. 06065C2029G
16. 06065C2017G
17. 06065C2007G
18. 06065C2036G
19. 06065C2028G
20. 06065C2009G
21. 06065C2026G
3-25
Figure 3-7 is a compiled FIRMs within the City limits.
Figure 3-7
Flood Plain & Flood Insurance Rate Maps
The following Specific Flood Hazard Area (SFHA) flooding sources have been identified based
on the above FIRMs. The development within these areas needs to be in full compliance with
the current National Flood Insurance Policy (NFIP) guidelines.
1. Lake Elsinore Overflow and Spillway Channel
2. Rice Canyon
3. McVicker Canyon
4. Sedco Hills Creek
5. Wash D
6. Arroyo Del Toro Creek
7. Stovepipe Canyon Creek
8. Temescal Wash
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Rice Canyon
Flooding from Rice Canyon is shown on FIRM Panels 06065C2017G and 06065C2008G and
would be caused by the failure of an earthen berm that is intended to direct the flows to the
northeast and into Temescal Wash. The berm failure allows the flow to breakout to the southeast
resulting in an area of expansive sheet flow.
McVicker Canyon
McVicker Canyon Channel Zone A floodplain is shown on FRIM Panels 06065C2016G,
06065C2008G, 06065C2017G, and 06065C2009G. The flooding as shown on the FIRMs is
indicative of a typical sheet flows on the alluvial fan below the mouth of the canyon. Review of
recent aerial photography of the area shows channel improvements which may alleviate the
hazard to these flood prone areas.
3-27
SECTION 4 - PROPOSED MDP FACILITIES AND ALTERNATIVES
A master drainage plan addresses the current and future drainage needs of a given community.
The proposed facilities may include channels, storm drains, levees, basins, dams, wetlands or
any other conveyance capable of economically relieving flooding problems within the plan area.
The plan includes an estimate of facility capacity, sizes and costs.
MDP's are prepared for a variety of purposes. First, the plans provide a guide for the orderly
development of the City and resolution of flooding issues. Second, they provide an estimate of
costs of construction for each established MDP zone. These plans are used by the City’s
Management, Community Development and Public Works Departments, Planning
Commissioners and the City Council to guide development and determine Capital Project
expenditures for each budget year. Finally, the plans will be used to establish Area Drainage Fees
for each MDP zone, which provide for equitable distribution of facility cost.
The City of Lake Elsinore MDP update consolidates the existing 51 drainage districts to three (3)
new and two (2) existing MDP Zones. New zones are: Temescal Wash Zone, Lake Zone and
East Lake Zone. Within the Temescal Wash Zone, an Alberhill Sub-Zone is established to
accommodate its unique development potentials and characteristics. The existing Riverside
County Flood Control and Water Conservation District West Elsinore MDP and Lakeland Village
MDP will remain unchanged.
Temescal Wash Zone
The Temescal Wash Zone, named for its receiving water Temescal Wash, encompasses an
approximately 13,230-acre watershed at the northwestern end of the Lake. Within its watershed,
an area of approximately 9,000-acre is within the City Boundary, of which 2,240 acres are
separated into Alberhill Sub-Zone. It is generally bordered by the city boundary to the north and
west, the West Elsinore MDP to the south and the Lake Zone to the east. Within the Temescal
Wash Zone, located at the northwest corner of the City, an Alberhill Sub-Zone is established due
to its unique development potentials and intensity and independence of the MDP facilities. In this
report, the MDP facilities for the Alberhill Sub-Zone are excluded from the Temescal Wash Zone
and treated as a stand alone zone.
The proposed Temescal Wash MDP facilities are comprised of four (4) debris basins and Ten
(10) storm drain systems. Two of the debris basins located north of Freeway I-15 (DB1 and DB2)
will benefit both Temescal Wash Zone and Alberhill Sub Zone, the cost of these two debris basins
are shared equally between Temescal Wash Zone and Alberhill Sub Zone. The location,
alignment and size of the Temescal Wash Zone MDP facilities are shown on Grid Map sheets A2,
B2 and B3 and Figure 4-1. The estimated total cost for Temescal Wash MDP facilities is
approximately $31,135,562.
4-28
Figure 4-1
Temescal Wash Zone MDP Facilities
4-29
Line T01 Storm Drain System
Line T01 Storm Drain system consists of a mainline storm drain and two laterals. The upstream
portions of the drainage system are located within Vesting Tentative Tract Map (VTTM) No.
36557. Line T01 begins near the northeast tract boundary and collects runoff from the offsite
areas to the west in a 48” RCP. From there, the 48” RCP extends in a southerly direction for a
distance of approximately 500 feet to the confluence with T01-01. At the T01-01 confluence, the
48” RCP transitions into a 72” RCP and extends in a northeasterly direction for a distance of
approximately 1,800 feet and outlets into a natural wash at the tract’s northern boundary. From
there, Line T01 is a natural unimproved channel for a distance of approximately 3,000 feet until it
crosses an unnamed Road (dirt road crossing) near Nichols Road. Line T01 transitions into a 72”
RCP and extends in an easterly direction for a distance of approximately 1,400 feet and outlets
into Temescal Creek. Lateral T01-01 begins near the southwestern boundary of VTTM 36557 and
joins with an existing 36” storm drain from the adjacent development. From there the 36” RCP
extends easterly along Terra Cotta Road for a distance of approximately 1,300 feet and
confluences with Line T01. Lateral T01-02 begins near the intersection of Dryden Street and
Arnold Avenue as a 36” RCP. From there the 36” RCP extends northwesterly along proposed
Terracina Drive and transitions into a 42” RCP at proposed Sicily Drive. The 42” RCP continues
along proposed Terracina Drive for a distance of approximately 400 feet then outlets into the in-
tract water quality/detention basin.
The estimated cost for the proposed Line T01 is approximately $3,870,000.
Line T02 Storm Drain System
Line T02 Storm Drain system consists of a mainline storm drain and two laterals. The upstream
portions of the drainage system (Laterals T02-01 and T02-02) are located within Vesting Tentative
Tract Map (VTTM) No. 36557. The upstream origin of Line T02 begins near the northwest
boundary of VTTM 36557 at the proposed in-tract water quality/detention basin outlet as a 66”
RCP. From there the 66” RCP follows an existing wash in a northeasterly direction for a distance
of approximately 2,100 feet. At Baker Street, the 66” RCP transitions into a 78” RCP and continues
in a northwesterly direction for a distance of approximately 950 feet and outlets into the Temescal
Wash. Lateral T02-01 begins near the intersection of Bulluno Way and proposed Venice Lane
(per VTTM 36557) at the edge of the development to collect runoff from offsite hillside areas as a
42” RCP. From there the 42” RCP extends northeasterly along proposed Venice Lane and turns
northwesterly and follows the northern tract boundary and confluences with Line T02. Lateral T02-
02 begins at the intersection of proposed Porta Marina Lane and Swan Avenue as a 36” RCP.
From there the 36” RCP extends northwesterly along Swan Avenue and turns northeasterly at
Dryden Street. At Sicily Drive, the 36” RCP transitions into a 42” RCP, and then extends in a
northerly direction towards Dolbeer Street as a 48” RCP. At the south end of Dolbeer Street, the
48” RCP transitions into a 54” RCP and extends northerly along Dolbeer Street and then turns
easterly at proposed Florence Drive. From there the 54” RCP follows Florence Drive for
approximately 1,300 and turn northerly and outlets into the in-tract water quality/detention basin.
The estimated cost for the proposed Line T02 is approximately $5,412,000.
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Line T03 Storm Drain System
Line T03 consists of a single mainline storm drain. Approximately 225 acres of sub-watershed
drain to Line T03, with its upstream 161.1 acres zoned as rural mountainous residential and low
density residential, and its downstream 63.9 acres zoned as manufacturing. The natural, well
defined drainage courses will be utilized for the rural low density areas. An underground storm
drain system will convey the storm runoff from the natural drainage course through the
manufacturing zone to Temescal Wash.
Line T03 begins as a 66” RCP and extends northerly along its natural drainage course for a
distance of approximately 900 feet. At Baker Street, the 66” RCP transitions into a 72” RCP and
follows Baker Street in a northwesterly direction for a distance of approximately 450 feet. From
there, the 72” RCP transitions into a 78” RCP and extends in a northerly direction for
approximately 500 feet and outlets into the Temescal Wash.
The estimated cost for the proposed Line T03 is approximately $1,723,000.
Line T04 and T05 Storm Drain System
Line T04 and T05 are located at southwesterly of District’s Gunnerson Pond, near upstream end
of Temescal Wash, zoned mostly hillside residential. Currently there is no existing storm drain
facility for this 138-acre sub-watershed. Our field investigation indicated that this area experiences
some hillside storm runoff flooding, erosion, street flooding and ponding at varies locations.
Line T04 is a 36” RCP storm drain, begins at Herbert Street, extends southeasterly 220 feet to
McBride Avenue, and extends approximately 310 feet easterly along McBride Avenue, crosses
Gunnerson Street and outlets into the Gunnerson Pond. Line T05 is a single mainline storm drain
on Shrier Drive. Its size varies from 54” RCP to 60” RCP, with total length approximately 1000
feet, and also outlets into the Gunnerson Pond.
The estimated costs for Line T04 and T05 are approximately $196,000 and $642,000 respectively.
Line T06 Storm Drain System
Line T06 is a 42” RCP single line storm drain. It begins at the intersection of Stecher Avenue and
Foster Street, extends approximately 1250 feet northerly along Foster Street, outlets to the
EVMWD pond easterly of Gunnerson Pond. The upstream end of Line T06 consists of 61.4 acres
of steep hill side zoned as rural mountainous residential, the well-defined natural water courses
will be utilized for storm runoff conveyance.
The estimated cost for the proposed Line T06 is approximately $519,000.
Line T07 Storm Drain System
Line T07 is a single line storm drain. It begins at intersection of Strickland Avenue and Palm Drive
as a 36” RCP, extends approximately 250 feet northwesterly along Strickland Avenue, at Bastron
Avenue, 36” RCP transitions to 42” RCP, it continues in a northeasterly direction for approximately
450 feet, then outlets to the existing EVMWD drainage ditch.
The estimated cost for the proposed Line T07 is approximately $292,000.
4-31
Line T08 Storm Drain System
Line T08 is a single line storm drain system; it can also be identified as Chaney Street Storm
Drain. It begins at the intersection of Strickland Avenue and Chaney Street as a 36” RCP, extends
approximately 360 feet northwesterly along Chaney Street, at Treleven Avenue, 36” RCP
transitions to 54” RCP, it continues northerly along Chaney for approximately 550 feet, then
discharges to the 42” stub out of Outlet Channel.
Currently, Chaney Street at Treleven Avenue and Strickland Avenue intersections experience
some street flooding and ponding during and after a rain storm. The construction of Line T08 with
its inlets and catch basins will reduce or eliminate the flooding. The capacity of existing 42” stub
out at the southeast quadrant of Chaney Street and Outlet Channel shall be verified during the
final design of the Line T08.
The estimated cost for the proposed Line T08 is approximately $432,000.
Line T09 Storm Drain System
Figure 4-2 Line T09 Lower Portion Exhibit
Line T09 is a storm drain system also known as Third Street Storm Drain. The upper portion of
the Line T09 begins at Cressida Street basin outlet as a 48” RCP (Tract 26476, MB 403/7-29)
extends approximately 760 feet southwesterly along a natural ravine, transitions to 60” RCP for
approximately 1,030 feet, transitions to 66” RCP and continues westerly along a natural water
course for approximately 1,600 feet, then discharges to the defined water course / open space
Lot “C” per Tract 25479, MB 367/95-113. h
The lower portion of the Line T09 system consists of one main line and two laterals. The proposed
Line T09 begins at northerly boundary of TTM 32537; it travels southerly between lots 9 and 10
as a 72” RCP, then continues westerly and southerly along “A” Street for approximately 920 feet.
At the intersection of “A” Street and Welch Drive, it extends southwesterly following Welch Drive
for approximately 700 feet, turns southeasterly along Conard Avenue for 550 feet then turns
4-32
southwesterly on Third Street for approximately 1300 feet. At the intersection of Third Street and
Cambern Avenue, the 72” RCP Line T09 confluents with Line T09-02, and transitions to 78” RCP
and extends 1,140 feet on Third Street. It transitions to a 96” RCP, Continue further southwesterly
on Third Street for 290 feet, confluences with Line T09-01 at south of Dexter Avenue, travels
toward I-15 for 260 feet. A Jack and Bore or tunneling operation is proposed for the 96” RCP
crossing under the I-15 Freeway, then transition to a 5’x10’ RCB for 310 feet, and finally transitions
to double 14’ wide x 4.5’ high RCB to join the existing double RCB at Collier Avenue.
Since the Line T09 System is the most costly system within the Temescal Wash Zone, the design
alternatives were reviewed during the preliminary and final design of the Third Street Storm Drain.
The current alignment and freeway crossing method was selected as the most viable alternative.
Furthermore, the upper portion of the Line T09 may be replaced by an enhanced natural drainage
channel and open spaces, if the proposed land planning incorporates such a design feature.
Line T09-01 is a single line storm drain lateral, it’s upstream portion within Tentative Tract Map
35422 consists of approximately 2,000 feet of 36” RCP, a 720 feet of double 48” RCP and three
on-site detention and water quality basins. At TTM 35422 southwesterly boundary, the double 48”
RCP transitions to a 60” RCP, travels in a westerly direction to discharge into mainline T01 south
of the intersection of Third Street and Dexter Avenue.
Line T09-02 is also a single line storm drain lateral of 48” RCP, approximately 410 feet in length
on Cambern Avenue. This lateral is designed to collect and convey the storm drain runoff at the
low point of Cambern Avenue to Line T09 to enable the development of the Walmart site.
The estimated cost for the proposed Line T09 System is approximately $12,803,000.
Line T10 Storm Drain System
Line T10 Storm Drain System is located immediately north of State Route 74, with Crumpton
Road on the east, and the City boundary on the west. It’s located at south end of North Peak
Specific Plan, zoned mostly for commercial use. The Line T10 System consists of a storm drain
mainline, one lateral and one debris basin. Debris Basin DB10 is located at the upstream terminus
of Line T10-01 and has a drainage area of 131 acres, sediment storage volume of approximately
1.7 acre-feet and an approximate right-of-way of 0.4 acres.
The upstream segment of Line T10 Storm Drain begins at a natural low point on Mauricio Street
east of Crumpton Road as a 36” RCP. It travels southerly for 300 feet then transitions to a 42”
RCP, turns westerly along the natural stream line for a distance of approximately 1,480 feet. The
42” RCP then transitions to 48” RCP and continues in a westerly direction for a distance of 1,600
feet. After confluence with Line T10-01, the 48” RCP increases to a 78” RCP for 330 feet, and
discharges at the City boundary approximately 500’ north of SR 74.
Line T10-01 begins at the outlet of the proposed Debris Basin DB10 as a 48” RCP runs
southwesterly along the natural water course for a distance of 480 feet and transitions to a 66”
RCP for a distance of 370 feet, then confluences with Mainline T10.
The estimated cost for the proposed Line T10 System is approximately $2,652,000.
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Debris Basins DB1 and DB2
Debris Basins DB1 and DB2 are located approximately 1,800 feet north of the intersection of I-15
freeway and Lake Street, at northerly boundary of Alberhill Ranch Specific Plan. Debris Basin
DB1 has a drainage area of 949 acres with an estimated debris volume of 18.7 ac-ft. Debris Basin
DB2 has a drainage area of 1,425 acres with an estimated debris volume of 25.6 ac-ft. These two
basins benefit both Temescal Wash Zone and Alberhill Sub-Zone. More importantly, when
constructed and maintained, they will reduce the silt and debris and improve the water quality of
the Temescal Wash. The estimated cost is approximately $1,471,000 and $2,014,000
respectively. At the recommendation of the City, the costs for these two debris basins are shared
by Temescal Wash Zone and Alberhill Sub-Zone equally.
Debris Basins DB5
Debris Basins DB5 is located south of Nichols Road and north of I-15. Debris Basin DB5 has a
drainage area of 822 acres with an estimated debris volume of 12.3 ac-ft. Currently, after each
storm event, silt and debris wash over to the Elsinore Outlet Center through existing Caltrans
culverts, placing heavy demands on City’s maintenance and operation resources and budget. By
placing DB5 on an alignment upstream of the Caltrans 14’x6’ Box Culvert, it will intercept and
store the debris in the DB5, reduce the impact to the Outlet Center and demand on the city
resource, and improve the water quality of the Temescal Wash.
The estimated cost for DB5 is approximately $968,000.
Debris Basins DB10
Debris Basins DB10 is located at the upstream end of MDP T10-01 System. Debris Basin DB10
has a drainage area of 131 acres with an estimated debris volume of 1.7 ac-ft. Since most of the
DB10 drainage areas are undeveloped land, DB10 will not only benefit water quality, maintenance
and operation, but also reduce the size of MDP T10-01 and T10, so 100-year storm event runoff
will not need to be bulked due to the debris loading.
The estimated cost for DB10 is approximately $134,000.
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Alberhill Sub-Zone
Alberhill Sub-Zone is located within the Temescal Wash MPD Zone and is made up of several
Specific Plans (SPs). Located within this MDP Sub-Zone are the Alberhill Village SP, Alberhill
Ranch SP, and the Murdock Alberhill Ranch SP. The Alberhill Sub-Zone is located in the
northwestern portion of the city, bounded by the West Elsinore MDP to the south, Santa Ana
Mountains to the west, northern city boundary to the north, and Temescal Creek to the east. The
Alberhill Sub-Zone encompasses approximately 2,240 acres and includes nine (9) separate sub-
watersheds which drain into the Temescal Wash as shown on Grid Sheets A1 and A2.
The area is primarily comprised of undeveloped land that is currently being mined for its mineral
resources (clay sand, and aggregate mining), and as a result most of the area is highly disturbed
due to the current and past mining operations. Alberhill Ridge Vesting Tentative Tract Map
(VTTM) No. 35001 is located on the east side of Lake Street proposes a 400 acre medium density
residential development. Alberhill Villages, located on the west side of Lake Street proposes a
1,400 acre development. It includes plans for a multifaceted community consisting of a university
campus, recreational lake, park areas, and residential developments ranging from low density
estates lots to high density multi-family lots, and mixed-use commercial and public institutions
and schools. The proposed MDP facilities within the Alberhill Sub-Zone mostly utilize the
alignment, type and size of the storm drain depicted in the supplemental drainage studies for the
Specific Plans and Tentative Maps.
The proposed MDP facilities are comprised of five (5) debris basins, eleven (11) storm drain
systems and nine (9) discharge points at the Temescal Creek. Two of the debris basins located
north of the I-15 Freeway (DB1 and DB2) will benefit both Temescal Wash Zone and Alberhill Sub
Zone, the cost of these two debris basins are shared equally between Temescal Wash Zone and
Alberhill Sub Zone.
The proposed underground storm drains consist of reinforced concrete pipes ranging in size from
36 inches to 108 inches in diameter. Reinforced concrete boxes were used when the capacity of
a 108 inch diameter pipe was exceeded. Open channels are trapezoidal shape with concrete
paving on the sides and bottom. The sides slope upward from the bottom at a rate of one foot
vertically for every 1.5 feet horizontally. The location, alignment and size of the proposed Alberhill
Sub-Zone MDP facilities are depicted on Grid Map sheets A1 & A2. The estimated total cost is
approximately $66,000,000.
Line A01 Storm Drain System
Line A01 Storm Drain is located in Watershed A01 of the Alberhill Villages SP and consists of a
single 36” diameter RCP extending approximately 950 feet from its upstream terminus (adjacent
to the existing Horsethief Canyon development) to its downstream outlet at the city boundary.
From this point it is assumed that the flows will follow their natural drainage course (a distance of
1,400 feet) to Temescal Creek.
4-35
Line A02 Storm Drain System
Line A02 Storm Drain System is located in Watershed A02 of the Alberhill Ranch SP and consists
of a mainline, one lateral and a debris basin. Line A02 Debris Basin (DB8) is located at the
upstream terminus of Line A02 and has a sediment storage volume of approximately 9.0 acre-
feet. Line A02 Storm Drain is an open channel with a bottom width of 8 feet and a height of 4 feet.
It begins at the proposed debris basin and runs in a northeasterly direction, crosses two proposed
streets, for a distance of about 3,000 feet and terminates at the city boundary. From this point it
is assumed than the flows will follow their natural drainage course (a distance of 1,200 feet) to
Temescal Creek. Lateral A02-01 varies in size from a 36” diameter pipe at its upstream end to a
48” diameter pipe at its confluence with Line A02. The overall length is approximately 2,400 feet.
Line A03 Storm Drain System
Line A03 Storm Drain System consists of a single mainline storm drain and is located in
Watershed A03 of the Alberthill Ranch SP. It has a total drainage area of approximately 72 acres
at its most downstream outlet point. Line A03 Storm Drain varies in size from a 36” diameter pipe
at its upstream end to a 48” diameter pipe at its downstream terminus at the city boundary for a
distance of approximately 2,300 feet. From this point it is assumed than the flows will follow their
natural drainage course (a distance of 900 feet) to Temescal Creek.
Line A04 Storm Drain System
Line A04 Storm Drain System is located in Watershed A04 of the Alberhill Ranch SP and consists
of a mainline, one lateral and two debris basins. Line A04 Debris Basin DB9 is located at the
upstream terminus of Line A04 and has a sediment storage volume of approximately 54.7 acre-
feet and an approximate right-of-way of 11.5 acres. The upstream segment of Line A04 Storm
Drain is an open channel with a bottom width of 20 feet and a height of 4 feet. It begins at the
proposed Debris Basin DB9 and runs northerly along the west side of Lincoln Street for a distance
of 3,000 feet and ends at Debris Basin DB9A.
Debris Basin DB9A is located approximately 1,500 north of the intersection of the future Lincoln
Street and the future extension of Nichols Road and has a sediment storage volume of
approximately 6.8 acre-feet and an approximate right-of-way of 1.4 acres. Downstream of Debris
Basin DB9A, Line A04 is a double 10 feet wide by 10 feet high reinforced concrete box (RCB)
that runs northerly along the alignment of Lincoln Street for a distance of approximately 6,900 feet
and terminates at Temescal Creek.
Lateral A04-01 varies in size from a 42” diameter pipe at its upstream end to a 66” diameter pipe
at its confluence with A04. The overall length is approximately 2,600 feet.
Line A05 Storm Drain System
Line A05 Storm Drain System consists of a mainline storm drain, six laterals, and five sub-laterals
and is located in Watershed A05 of the Alberhill Villages SP and Alberhill Ridge VTTM 35001.
The overall drainage area at its downstream outlet at Temescal creek is approximate 1.8 square
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miles. The upstream origin of Line A05 begins at an existing detention basin located just north of
the intersection of Lake Street and Nichols Road, and runs in a northerly direction along the
alignment of Lake Street and terminates at Temescal Creek, for a distance of approximately 1.1
miles. Line A05 varies in size from a 78” diameter pipe at its upstream end to a 108” diameter
pipe at the confluence with Line A05-02. At the Line A05-02 confluence, the 108” RCP transitions
to a 12 feet wide by 10 feet high RCB. From there, the 12’x10’ RCB extends northerly along Lake
Street and transitions to a double 10 feet high by 10 feet wide RCB at the A05-1 confluence. From
the Line A05-01 confluence to the outlet at Temescal Creek, the size remains constant at a double
10 feet wide by 10 feet high RCB.
The upstream origin of Lateral A05-01 begins at the intersection of proposed Alberhill Ridge Road
and “JJ” Street (per Alberhill Ridge VTTM 35001) as a 36 inch RCP. From there, the 36 inch RCP
follows the alignment of Alberhill Ridge Road in a northwesterly direction for a distance of
approximately 1,700 feet (with a short reach of 42 inch RCP) where it confluences with Storm
Drain Line A05.
The upstream origin of Lateral A05-02 begins at the intersection of proposed “AA” Street and
“GG” Street (per Alberhill Ridge VTTM 35001) as a 36 inch RCP. From there, Lateral A05-02
follows the alignment of “AA” Street and ”A” Street in a westerly direction for a distance of
approximately 2,250 feet, where it confluences with Storm Drain Line A05 and varies in size from
a 36” RCP to 72” RCP. Lateral A05-02-01 begins at the intersection of “Z” Street and “V” Street
as a 36” RCP. From there, the 36 inch RCP follows the alignment of “V” Street in a northwesterly
direction for a distance of approximately 600 feet (with a short reach of 42 inch RCP) where it
confluences with Storm Drain Line A05-02.
The upstream origin of Lateral A05-03 begins at about 1,000 feet south of the intersection of the
future Nichols Road and Street C (per Alberthill Villages SP) as a 42” RCP and runs northerly
along the alignment of Street “C” for approximately 2,000, feet then turns easterly along an
unnamed street for a distance of approximately 2,400 feet where it confluences with Storm Drain
Line A05. Lateral A05-03 varies in size from a 42” RCP to a 72” RCP at its downstream
confluence. Lateral A05-03 has two sub-laterals: A05-03-01 and A05-03-02. Lateral A05-03-01
begins at approximately 750 feet west of Street C, varies in size from a 36” RCP to a 48” RCP
and ends at the confluence with Lateral A05-03 for a distance of approximately 1,150 feet. Lateral
A05-03-02 begins at approximately700 feet west of Street C as a 36” RCP and follows the
alignment of Nichols Road to the confluence with Lateral A05-03.
Lateral A05-04 begins at the intersection of Street D and Nichols Road (per Alberhill Villages SP)
as a 36” RCP. From there the 36” RCP extends northwesterly for approximately 1,750 feet to a
point where it confluences with Storm Drain Line A05.
Lateral A05-05 begins at the intersection of “AA” Street and “BB” Street (per Alberthill Ridge VTTM
35001) as a 36” RCP and immediately transitions to a 42” RCP. From there the 42” RCP extends
westerly along “BB” Street and transitions into a 54” RCP at the intersection of “GG” Street and
“BB” Street. The 54” RCP continues westerly along “BB” Street and then transitions into a 60”
RCP at the intersection of “AAA” Street and “BB” Street, and continues as a 60” RCP to the
confluence with A05-05-1 where it transitions into a 72” RCP. The 72” RCP extends southerly
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along “BB” Street until it confluences with Line A05 at Lake Street. Lateral A05-05-01 begins near
the intersection of “N” Street and “B” Street as a 42” RCP. From there the 42” RCP extends
southerly along “B” Street until it confluences with Lateral A05-05.
Lateral A05-06 begins at the intersection of “CC” Street and “ZZ” Street (per Alberhill Ridge VTTM
35001) as a 36” RCP. From there the 36” RCP extends southerly along “CC” and transitions into
a 42” RCP at the intersection of “PP” Street and “CC” Street. The 42” RCP continues southerly
along “CC” Street, crosses Alberhill Ridge Road and transitions into a 60” RCP at the intersection
of “J” Street and “C” Street. The 60”then continues along “C” Street and transitions into a 66” RCP
at the intersection of “T” Street and “C” Street. From there the 66” RCP extends approximately
800 feet along “C” Street, then transitions into a 72” RCP continues along “C” Street and
confluence with Line A05 at Lake Street.
Storm Drain Line A06
The upstream origin of Storm Drain Line A06 begins at the proposed park located at the northwest
corner of the intersection of Lake Street and Alberhill Ranch Road. Line A06 begins as a 36” RCP
and extends through the park for a distance of about 1,400 feet and transitions into a 42” RCP,
then follows along the northern park boundary to Street D where it transitions into a 48” RCP. The
48” RCP then extends northerly along Street D and turns easterly at Nichols Road and transitions
into a 54” RCP at approximately 650 feet west of Lake Street. The 54” RCP continues along
Nichols Road and confluence with the existing storm drain along Lake Street.
Storm Drain Line A07
The upstream origin of Storm Drain Line A07 begins at approximately 1,100 feet northeast of the
intersection Nichols Road and Alberhill Ridge Road (per Alberhill Ridge VTTM 35001) as a 36”
RCP. From there the 36” RCP extends southwesterly for approximately 1,100 feet and turns
northwesterly on Lake Street where it confluences with an existing storm drain on Lake Street.
Line A08 Storm Drain System
Line A08 Storm Drain System consists of a mainline storm drain and three lateral storm drains.
The overall drainage area at its downstream outlet at Temescal Creek is approximate 205 acres.
The upstream origin of system A08 begins approximately 900 feet southwest of the intersection
of Alberhill Ridge Road and Nichol Road as a 36” RCP. From there the 36” RCP runs easterly
along Nichols Road and transitions into a 72” RCP at the confluence with A08-03 and continues
easterly along Nichols Road. At the confluence with A08-02, the 72” RCP transitions into a 78”
RCP, continues easterly for approximately 1,900 feet and terminates in a natural wash along the
south side of Nichols Road.
Lateral A08-01 begins at the intersection of “F” Street and “A” Street (Tract Map Nos. 30836 &
37553) as a 36” RCP. From there, the 36” RCP extends southerly along “A” Street for
approximately 400 feet and transitions into a 42” RCP. The 42” RCP extends southerly along “A”
Street until it confluences with Line A08 at Nichols Road. Lateral A08-02 begins at approximately
1,700 feet north of Nichols Road as a 36” RCP. From there, the 36” extends southerly along a
4-38
natural wash for approximately 600 feet and transitions into a 42” RCP. The 42” RCP continues
along the wash until it confluences with Line A08 at Nichols Road. Lateral A08-03 is a 36” RCP,
begins at approximately 980 feet north of Nichols Road, and extends southerly confluences with
line A08 at Nichols Road.
Line A09 Storm Drain System
Line A09 consists of a single mainline storm drain. The overall drainage area at its outlet at
Temescal Creek is approximately 84.8 acres. The upstream origin of storm drain Line A09 begins
at the intersection of “O” Street and “P” Street (Tract Map Nos. 30836 & 37553) as a 36” RCP.
From there the 36” RCP extends southerly along “O” Street and transitions into a 42” RCP at “C”
Street. The 42” RCP extends easterly along “C” Street and then turns southerly at “D” Street.
From there the 42” RCP extends southerly along “D” Street and transitions into a 48” RCP at the
intersection of “N” Street and “D” Street. The 48” RCP continues southerly along “D” Street and
transitions into a 54” RCP prior to Nichols Road. The 54” RCP then turns easterly along Nichols
Road and terminates in Temescal Creek.
Line A10 Storm Drain System
Line A10 consists of a mainline storm drain and two laterals. Line A10 begins at approximately
1,900 feet east of the I-15 Freeway on Nichols Road as a 36” RCP. The 36” RCP extends westerly
along Nichols Road for about 900 feet and transitions into a 42” RCP then continues along Nichols
Road and transitions into a 54” RCP at the A10-02 confluence. The 54” RCP continues westerly
on Nichols Road for about 450 feet then turns northerly and follows the northbound freeway
onramp and connects with an existing double 54” RCP at the I-15 Freeway (Caltrans). The
upstream origin of Lateral A10-01 begins at the mouth of the natural canyon area, approximately
1,200 feet east of the I-15 Freeway as a 42” RCP. From there, the 42” RCP extends westerly
and confluences with Line A10. Lateral A10-02 begins in the proposed parking lot area of the
future retail center (Per Alberhill Ranch SP Amendment #3) as a 36” RCP. The 36” RCP extends
approximately 1250 feet to the northwest and confluences with Line A10. Lateral A10-03 collects
runoff at the mouth of the offsite canyon area where it intersects the edge of pavement. Lateral
A10-03 is a 36” RCP, approximately 300 feet and confluences with Line A10 just north of Nichols
Road.
Line A11 Storm Drain System
Line A11 consists of a single mainline storm drain. The upstream origins begin at the canyon
mouth of the hills approximately 800 feet to the east as a 48” RCP. The 48” RCP extends
southwesterly towards the I-15 Freeway and confluences with the existing Caltrans 48” RCP.
4-39
Lake Zone
Lake Zone is located in the northeasterly part of the City, encompasses an approximately 9,036-
acre watershed. Its receiving water is Lake Elsinore, directly or indirectly through Canyon Lake or
Lower San Jacinto River connecting Canyon Lake to Lake Elsinore. The Specific Plans within the
Lake Zone are Spyglass Ranch SP, Tuscany Hills SP, Canyon Creek (La Strada) SP, Canyon
Hills SP, Canyon Estates SP, City Center SP; The Specific Plans partially within the Lake Zone
include North Peak SP, Ramsgate SP and East Lake SP. These Specific Plans are in various
development stages, while the areas within Canyon Hills SP are mostly build out, North Peak and
Canyon Estates remain in their natural, undeveloped conditions.
The proposed Lake Zone MDP facilities are comprised of one (1) debris basin, one (1) debris/
detention basin and twenty-three (23) storm drain systems. The location, alignment and size of
the Lake Zone MDP facilities are depicted on Grid Map sheets A2, A3, B2, B3, C1 and C2 as
shown on Figure 4-3 below. The estimated total cost for Lake Zone MDP facilities is approximately
$ 32,422,000.
Figure 4-3
Lake Zone MDP Facilities
4-40
Line L-1 to L-5 Storm Drain Systems
Line L-1 to L-5 systems are located at the north shore of the Lake, west of the District’s Outlet
Channel. This area comprises mostly older residential neighborhoods with school, park and light
commercial uses mixed in. Currently there is no existing storm drain facility for this area. Our field
investigation indicated that this area experiences some street flooding and ponding at varies
locations along Lakeshore Drive and Heald Avenue. Line L-1 to L-3 sub-watersheds drain directly
to the Lake, Line L-4 and L-5 sub-watersheds drain to the lower Outlet Channel then discharge
to the Lake, as shown on Grid Sheet B3.
Line L-1 is a single line 36” RCP storm drain totaling 710 feet in length, begins at Heald Street,
extends westerly to Adam Avenue, and extends southerly to Lakeshore Drive, then southeasterly
along Lakeshore Drive and discharges into the Lake.
Line L-2 system starts at the intersection of Heald Avenue and Mohr Street, travels approximately
660 feet southerly along Mohr Street, turns westerly along Lakeshore Drive for 200 feet,
confluences with Line 2-1, then turns southerly for a distance of 290 feet and discharges into the
Lake. Line L2-1 is a 36” RCP single line storm drain which begins at the intersection of Heald and
Townsend Street, extends 360 feet along Townsend, turning southeasterly on Lakeshore Drive
and confluences with Line L-2.
Line L-3 is a single mainline storm drain. It size varies beginning as a 36” RCP along Lindsay
Street for a length of 1050 feet, then turns west along Limited Avenue and transitions to a 42”
RCP. From there the 42” RCP extends westerly for a distance of 670 feet, at the intersection of
Limited Avenue and Lakeshore Drive, Line L-3 turns southerly for approximately 300 feet and
outlets to the Lake.
Since Line L-1, L-2 and L-3 all directly discharge runoff to the Lake, appropriate water quality
treatments are required at the each discharge point.
Line L-4 is a 36” single line storm drain which begins at the intersection of Langstaff Street and
Pottery Street, travels along Pottery to the east for a distance of 420 feet, and outlets to an existing
24” stub out on Outlet Channel.
Line L-5 is a 36” single line storm drain which begins at Langstaff Street and terminates at Flint
Street, west of Outlet Channel, outlets to an existing stub out of the channel.
The estimated costs for Line L-1 to L-5 systems are approximately $2,269,000.
Line L-6 Storm Drain System
Line L-6 storm drain system consists of a mainline storm drain and an existing 54” Caltrans culvert
and 600’ feet of Caltrans concrete lined drainage ditch. The upstream origin of Line L-6 begins
approximately 520’ north of the existing 54” Caltrans culvert, along Elsinore Hill Road proposed
by Tentative Tract Map 35337, Spyglass Ranch as a 36” RCP, and discharges into the existing
54” pipe culvert south of the I-15 Freeway. Line 6 reassumes its alignment at the end of Caltrans
ditch near the north end of Lookout Street as a 42” RCP. From there the 42” RCP extends 330
feet southerly on Lookout Street, turns westerly along Flint Street as a 48” RCP for 340 feet,
increases its size to a 54” RCP for a distance of approximately 1,240, then discharges into the
Outlet Channel.
4-41
The estimated cost for the proposed Line L-6 system is approximately $1,235,000.
Line L-7 Storm Drain System
Similar to the Line L-6 system, Line L-7 storm drain system consists of a mainline storm drain and
three existing Caltrans culverts and a section of natural drainage ditch along the south side of the
I-15 Freeway. The upstream origin of Line L-7 begins approximately 1070’ north of the existing
39” Caltrans culvert, along a natural valley as a 36” RCP, and discharges into the existing 39”
pipe culvert north of the I-15 Freeway. Line 7 reassumes its alignment near the north end of Adobe
Street as a 42” RCP. From there the 42” RCP extends 790 feet southerly along Adobe Street,
turns westerly along Pottery Street as a 54” RCP for 1410 feet. At the intersection of Pottery Street
and Ellis Street, Line L-7 increases its size to a 60” RCP along Pottery Street for a distance of
approximately 1,070 feet and discharges into the Outlet Channel.
The estimated cost for MDP Line L-7 system is approximately $2,309,000.
Line L-8 and L-9 Storm Drain Systems
Line L-8 and L-9 systems are located east of the District’s Outlet Channel. This area comprises
mostly older residential neighborhoods with approximately 33 acres of steep hillside at its easterly
end. Currently there is no existing storm drain facility for this area. Our field investigation indicated
that this area experiences some street flooding, ponding and hillside erosion at various locations.
Line L-8 is a single line 36” RCP storm drain totaling 650 feet in length, which begins at Main
Street, extends westerly along Summer Avenue, and outlets to the Outlet Channel.
Line L-9 system is a single line 36” RCP storm drain totaling 600 feet in length, which begins at
Main Street, extends westerly along Franklin Street, and outlets to the Outlet Channel.
The estimated costs for Line L-8 and Line L-9 are approximately $535,000.
Line L-10 to L-13 Storm Drain Systems
Line L-10 to L-13 systems are located at the northeast corner of the Lake, between Ridge Road
and the San Jacinto River inlet channel. This area is comprised of mostly older residential
neighborhoods with an undeveloped steep hillside to the north, and a school and commercial site
to the east. Currently there are few existing storm drains within Line L-13 sub-watershed. Our
field investigation indicated that this area experiences some street flooding, ponding on Mill Street
near the Railroad Canyon Elementary School site and along Lakeshore Drive. Hillside erosion
and storm runoff which floods residents have also occurred on Avenue 6 and 7, along Country
Club Blvd. and Acacia Street. The areas south of Lakeshore Drive, east of Lakepoint Park are
within the East Lake Specific Plan. The land use within the SP is still evolving.
Line L-10 to L-13 Systems can be found on Grid Map Sheet B3, and also shown on Figure 4-4.
4-42
Figure 4-4
Lake Zone MDP Line L-10 to L-13
Line L-10 is a single mainline storm drain system which begins at Acacia Street extends southerly
along High Street, crosses Lakeshore Drive and outlets to the Lake. Line L-10 size varies from
36” RCP upstream to 72” RCP at the outlet near the Lake. The estimated cost for Line L-10 is
approximately $1,343,000.
Line L-11 system is a single mainline storm drain system, which begins at Mill Street and Avenue
2, extends westerly to Avenue 1, turns southerly along Avenue 1 to Lakeshore Drive, travels along
Lakeshore Drive in an easterly direction, turns south again along Lucene Street and outlets to the
Lake. Line L-11 size varies from 36” RCP upstream to 54” RCP at the outlet near the Lake. The
estimated cost for Line L-11 is approximately $1,300,000.
Line L-12 system is a single mainline storm drain system, which begins at Mill Street and Avenue
4, extends southerly to Parkway, turns easterly along Parkway then turns southerly on Pepper
Street to the intersection of Pepper and Dawe Street. From there Line L-12 travels along Dawe
Street easterly for a distance of 280 feet to Avenue 6, then turns southerly for a distance of
approximately 1200 feet and outlets to the Lake. Line L-12 size varies from 36” RCP upstream to
54” RCP at the outlet near the Lake. The estimated cost for Line L-12 is approximately
$1,252,000.
Line L-13 storm drain system consists of a mainline storm drain and one lateral. Currently there
is some street flooding and roadside erosion along Avenue 6, Avenue 7 and Mill Street. Existing
local storm drains and catch basins are on Mill Street that conveys the storm runoff to the concrete
ditch along westerly side of the Railroad Canyon Elementary School site, and outlets near the
Park Way Cul-De-Sac. The upstream origin of Line L-13 begins at Park Way Cul-De-Sac as a 36”
RCP, travels southerly 650 feet to Lakeshore Drive. From there the Line L-13 pipe size increases
to 42” RCP follows Lakeshore Drive in an easterly direction for 660 feet, increases to 48” RCP for
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a distance of 730 feet, confluences with Lateral L-13-1 and connects /outlets into the existing 75”
RCP Storm Drain. Lateral L-13-1 begins at the outlet of an existing storm drain at Park Way and
Avenue 12 as a 36” RCP. From there the 36” RCP follows the Avenue 12 alignment for a distance
of approximately 850 feet and then confluences with Line L-13.
The estimated cost for Line L-13 system is approximately $1,140,000.
Line L-14 Storm Drain System
Line L-14 Storm Drain System is a major drainage facility proposed to extend the Wasson Canyon
Channel Stage 1 facilities constructed by the District. The existing Wasson Canyon Channel
facilities began at south side I-15 Wasson Canyon Bridge as a collector channel, transitions to an
18 foot wide and 10.5 foot high RCB crosses under Collier Avenue to a debris basin, then
discharges into the Outlet Channel at its ridge point. Theoretically, Wasson Canyon storm runoff
will split evenly, 50 % draining to Lake Elsinore and 50% draining to Temescal Wash. Currently
there are no other existing master plan drainage facilities upstream of the I-15 Freeway Wasson
Canyon Bridge.
Addressee
Figure 4-5
Lake Zone MDP Line L-14 and Wasson Canyon Sub-watershed
Wasson Canyon sub-watershed is comprised of approximately 8 square miles of land, with a 100-
year peak flow of 3400 CFS, draining generally north to south. The mid and upper portion of the
canyon has a well-defined natural water course with year-round vegetation. At its lower (south)
end, south of Rosetta Canyon Drive, Wasson Canyon becomes flatter and less defined. Some
properties and city streets at south end of Wasson Canyon experienced some flooding and
erosion damage in the past. Based on the unit hydrographic studies, debris basin DB 6 analysis,
and input from the City, Line L-14 system is proposed.
4-44
Initially, the Line L-14 system was designed as a double 14’ x7’ RCB with total length of 1,960
feet with a debris basin DB6 at its upstream end. The total estimated cost for the RCB system
and DB 6 is approximately $8,908,000 and $ 5,979,000 respectively.
Due to the high cost of the Line L14 System, an alternative study of combined RCB (at Camino
Del Norte road crossing) and concrete lined channel was conducted. With the open channel
alternative, debris can be removed from the channel, and the existing debris basin south of the I-
15 Freeway can be utilized for silt and misc. trash removal. The estimated size of the lined
trapezoidal channel is 40 feet wide at the bottom with 1.5:1 side slopes and a depth of 7 feet. Due
to the significant cost savings, this alternative is selected for MDP Line L-14.
The estimated cost for Line L-14 system is approximately $3,740,000.
Line L-15 Storm Drain System
Line L-15 is a single mainline 36” RCP storm drain totaling 2,710 feet in length, proposed by
Spyglass Ranch, Tract 35337. The estimated cost for Line L-15 is approximately $938,000.
Line L-16 Storm Drain System
Line L-16 system consists of a mainline storm drain and a Lateral L-16-1, proposed by Tract
31593 South Shore I and Tract 36567 South Shore II in conjunction with on-site detention and
water quality basins. Line L-16 system discharges into Wasson Canyon drainage course.
The estimated cost for Line L-16 system is approximately $4,670,000.
Line L-17 – Line L-20 Storm Drain Systems
Figure 4-6
Lake Zone MDP Line L-17 to Line L-20
Line L-17 is a single mainline 36” RCP storm drain totaling 800 feet in length, located north of the
I-15 Freeway, west of Franklin Street.
4-45
The estimated cost for Line L-17 system is approximately $290,000.
Line L-18 storm drain system consists of a mainline and three Laterals. The upstream portion of
the Line L-18 system (Laterals L-18-2 and L-18-3 and two water quality basins) as shown on
Figure 4-6 was proposed by Tract 36567, South Shore II.
Line L-18 begins at Lateral L-18-3 basin outlet structure travels along future La Strada Road in a
southerly direction to Grunder Drive, then outlets to the existing Caltrans concrete ditch.
The estimated cost for Line L-18 system is approximately $2,775,000.
Line L-19 is a single mainline 60” RCP storm drain totaling 1,370 feet in length, located north of
Canyon View Drive, extending from the existing 72” storm drain constructed in conjunction with
the development of Canyon Creek Specific Plan.
The estimated cost for Line L-19 system is approximately $976,000.
Line L-20 is a single mainline storm drain. Totaling 800 feet in length, located north of Scenic
Ridge Drive, extending from the existing 66” storm drain. Line L-20 varies in size from a 36” RCP
at its upstream end to a 48” RCP at the downstream end and has an overall length of
approximately 1,730 feet.
The estimated cost for Line L-20 system is approximately $667,000.
Line L-21 Storm Drain System
Line L-21 Storm Drain System consists of a single mainline storm drain and is located in sub-
watershed L-21 of the Tuscany Hills SP. The upstream origin of Line L-21 begins approximately
850 feet southwest of the intersection of Greenwald Avenue and Little Valley Road as a 48” RCP.
From there the 48” RCP extends in a southerly direction along the proposed streets for a distance
of approximately 850 feet and outlets in a proposed water quality basin.
The estimated cost for Line L-21 system is approximately $528,000.
Detention Basin DB11
The purpose of this detention basin is to reduce peak flow rates in the downstream storm drain
system through the use of temporary detention storage. This peak flow reduction allows the use
of smaller, less costly downstream facilities. A combination detention/debris basin is proposed for
the upper portion of the Tuscany Hills Specific Area. The basin will reduce the downstream flow
rate due to the temporary storage effect (hydrograph attenuation) and due to the removal of
sediments (un-bulked). In addition it will be much easier and less costly to clean out a basin than
it would be to clean out an underground drainage system. The Tuscany Hills Debris/Detention
Basin DB11 has a volume of approximately 25.0 acre-feet and an approximate right-of-way of 5.3
acres.
Line L-22 Storm Drain System
Line L-22 storm drain system consists of a mainline storm drain and one lateral. The upstream
origin of Line L-22 begins near the northwest boundary of the Tuscany Hills SP at the proposed
Debris/Detention Basin DB11 outlet as a 42” RCP. From there the 42” RCP follows the proposed
streets in a southeasterly direction and outlets into a proposed water quality/detention basin. Line
4-46
L-22 varies in size from a 42” RCP at its upstream end to a 66” RCP at the downstream end and
has an overall length of approximately 4,300 feet. Lateral L22-1 begins at the western boundary
of Tuscany Hills SP as 36” RCP. From there the 36” RCP follows the proposed street alignment
for a distance of approximately 2,200 and then confluences with Line L-22.
The estimated cost for Line L-22 system including DB 11 is approximately $5,907,000.
Line L-23 Storm Drain System
Line L-23 storm drain system consists of a single mainline storm drain. The upstream origin of
Line L-23 begins at the western boundary of the Tuscany Hill SP and collects offsite runoff from
the hills to the west and conveys it through the development and discharges the runoff in a natural
wash to the south. Line L-23 varies in size from a 36” RCP at its upstream end to a 42” RCP at
the downstream end and has an overall length of approximately 15100 feet.
The estimated cost for Line L-23 system is approximately $550,000.
4-47
East Lake Zone
The East Lake Zone, named for the East Lake Specific Plan, covers approximately 3000-acres at
the southeastern end of Lake Elsinore. It is generally bordered by the city boundary to the south
and east, the lake to the west and the San Jacinto River Inlet Channel to the north. Most of the
East Lake Zone lies within a 100-year flood plain; as a result, the East Lake Zone has been
significantly impacted during wet seasons.
A joint powers authority named Lake Elsinore Management Authority was formed in the late-
1980s, it led the efforts to stabilize the fluctuating level of water in the lake. As a component of
those efforts, the levee along the East Lake Zone northern boundary was constructed in 1995.
The levee effectively reduced the size of the water surface by about half resulting in reduction of
lake evaporation. The levee also provided flood protection for the East Lake Zone.
The development within the East Lake area is primarily governed by the approved East Lake
Specific Plan, its development agreements and amendments. The East Lake SP Amendment 8
established that the lowest floor in all development areas shall be raised above the FEMA 100-
year flood plain elevation of 1267 feet mean sea level. To allow for regional flood storage, the set
aside open space and park will be graded to an elevation of 1240 or below, no import earth shall
be used to raise the building pad areas.
Figure 4-1
East Lake Zone
4-48
Within the East Lake Zone, the existing developments include a master planned residential
neighborhood, “Summerly” (Tract 31920); an 18-hole golf course “The Links at Summerly”; a
limited mix of industrial and commercial; an air strip with hangers and supporting facilities and
medium-density residential developments at southeast corner.
Currently, existing drainage facilities that provide some level of flood protection within this zone
are as follows:
City Facilities
Pete Lehr Drive Storm Drain (54” RCP)
Storm Drain systems associated with Tract 31920 Summerly developments
Storm Drain systems associated with Tract 30846 developments
Ontario Way Storm Drain (84” RCP)
District Facilities
Palomar Channel (Tract 30846)
SEDCO MDP Line D (daylight channel)
SEDCO MDP Line E (daylight channel)
Located across Mission Trail and Corydon Street in the City of Wildomar is the Riverside County
Flood Control and Water Conservation District SEDCO MDP. The storm runoffs from SEDCO
area with approximate 2,675 acres of land discharge to the back basin, the area behind the levee
bounded by the City limits, with Wildomar on the north, east and south in the East Lake Zone.
This discharge of runoff has a significant impact to the proposed land use and flooding within the
back basin of the East Lake Zone. The District’s Master Drainage Plan for the SEDCO Area dated
March 1982 proposes Lines A, B and C. These facilities were reevaluated with City of Wildomar
MDP, and the 100-year peak discharge rates provided by the City of Wildomar on December 11,
2019, are used for sizing the proposed storm drain facilities.
4-49
The proposed Storm Drain Line E-1 and Line E-2 systems are designed to accept the Wildomar
MDP Line A through E peak flows, convey the runoffs to the designated open spaces for storm
water storage, mitigation and ultimately discharging to the lake.
Line E-1 Storm Drain System
The Line E-1 Storm Drain System is located west of the Mission Trail / City boundary and east of
“Summerly” developments.
Line E-1-1 is a single cell 12’ (width) x6’ (depth) RCB, the upstream end begins at Mission Trail
and Sedco Blvd, as an outlet for combined Line A, B & C of the Sedco MDP storm drain. Line E-
1-1’s overall length is approximately 2,100 feet at its confluence junction with Line E-1.
Line E-1 is a double-cell RCB system, with its size varying from a double 8’ x7’ at Mission Trail
and Vine Street to a double 10’x8’ at its outlet. The Line E-1 upstream segment, approximately
1,850 feet in length, has the capacity of 1,515 CFS for combined Line D and Olive Street Storm
Drain per the Wildomar MDP study. The downstream segment from the confluence point with Line
E-1-1 to its outlet is approximately 2,400 feet.
The existing Sedco MDP Line D was designed and constructed in the mid-1980s. It was drastically
undersized according to the Wildomar MDP study. The existing Line D daylight channel at the
west of Mission Trail will need to be removed for Line E-1 construction.
The estimated cost for the proposed Line E-1 system is approximately $14,635,000.
Line E-2 Storm Drain System
The Line E-2 Storm Drain System is located south of the intersection of Mission Trail and Corydon
Road. The proposed Line E-2 is a double-cell RCB which ranges from double 8’x6’ to double 8’x7’
RCB, with an approximate overall length of 2,150 feet. Line E-2 is intended to convey storm
runoffs from Sedco Line E through East Lake developments to the open spaces.
Per the Wildomar MDP study, Sedco MDP Line E has a 100-year storm peak rate of 1318 CFS.
However, the portion of Sedco Line E constructed in 2004 was designed for 450 CFS. The existing
Sedco Line E consists of a daylight channel, a segment of 149 feet of 72” RCP with bulkhead at
the upstream end, and a 42” RCP lateral with 4 catch basins at Mission Trail and Lemon Street
with total design capacity of 68 CFS.
Currently Corydon Street experiences severe flooding during rain storms, mainly due to the lack
of drainage facilities. Only 5% of the 100-storm is conveyed through the existing Line E and its
laterals, the bulk of the storm conveyance on Corydon Street is surface flow, which creates un-
safe driving conditions.
At the request of the City, Webb provided an interim solution with 2 design options to alleviate
Corydon flooding. The recommendations and exhibits are provided in Appendix X for reference.
The estimated cost for the proposed Line E-2 system is approximately $4,686,000.
4-50
Line E-3 Storm Drain System
The Line E-3 Storm Drain System is located in the Airport Use Area of the southeasterly corner
of the East Lake Zone. Line E-3 consists of a single mainline storm drain. It varies in size from a
54” RCP upstream end to a 66” diameter RCP at its downstream, terminus within open space for
a distance of approximately 1,500 feet. The Line E-3 watershed includes an approximate 24 acre
drainage area from the City of Wildomar at the southeasterly area of Corydon Street.
The estimated cost for the proposed Line E-3 is approximately $958,000.
Line E-4 Storm Drain System
The Line E-4 Storm Drain System is located in the west side of the East Lake Zone, where the
current land use is low to medium density residential. Line E-4 consists of a single mainline storm
drain, which varies in size from a 48” RCP upstream end to a 66” diameter at its outlet. This area
is surrounded by open space. The areas adjacent to open space can be graded to drain to the
open space via surface flow. It is anticipated that land use will be modified in the near future. The
proposed Line E-4 will need to be adjusted accordingly.
The estimated cost for the proposed Line E-4 is approximately $1,153,000.
A summary of the proposed facilities and their estimated cost is shown below.
Line E-1
Line E-2
Line E-3
Line E-4
Total
$ 14,635,000
$ 4,686,000
$ 958,000
$ 1,153,000
$21,432,000
Alternative Studies
The proposed Line E-1 and Line E-2, utilizing Reinforced Concrete Box culverts, are the most
costly and also the most versatile systems. The alternatives of using concrete lined trapezoidal
channels or earthen channels are examined and analyzed for their feasibility, both hydraulically
and economically.
a. Concrete Lined Trapezoidal Channel
This alternative uses concrete lined open channels with channel side slope 1.5 to 1; base width
6’ to 20’ and depth 6’ to 7’. The open channels will have two maintenance access roads, one on
each side of the channel, the estimate right of way requirements vary between 43’ to 75’ in width.
The channel will transition to a RCB of equivalent capacity where it crosses roadway. A total of 4
roadway crossings are assumed for the cost estimate comparison.
b. Un-lined Trapezoidal Earthen Channel
The earthen channel will require 4:1 side slope and much wider bottom base width to achieve a
non-erosive velocity. If earthen channels are used for Line E-1 and Line E-2, the bottom width of
4-51
the earthen channels will range from 30’ to 90’, the total width of the channel will need to be as
wide as 190’. Conceptually, the earthen channel may provide opportunity for infiltration and bio-
treatment within the channel footprints, and be less costly. However, due to its width, it requires
much longer transition structures at roadway crossings, and acquisition of more Right-of-Way.
A summary of the alternative studies is presented in the table below:
East Lake MDP Cost Alternative Summary
Wildomar
MDP
Alt 2 - Concrete
Trap Channel
Alt 3 - Earth
Channel 4:1Required Add'l Imp East Lake MDP Alt 1 - RCB
Bottom
Width
Bottom
WidthQ100
(cfs)
Q100
(cfs)
Length Size
(ft)
D DWildomar East Lake
MDP MDP
LINE E1-1
LINE E1
(ft)(ft)(ft)(ft)(ft)
LINE A
LINE B
LINE C
LINE O
LINE D
248 Extend Line A & B to
Line C on Mission Trail
by Wildomar
222
237 688-784 2100 12'x6'6 6
7
30
56
5.5
6.5
252 Extend Line O to Line D
on Mission Trail1290
2249
1318
1515 1850
2400
2150
2-8'x7'12
LINE E1
LINE E2
(Sum of Line A-D)2426-2552
1318-1466
2-10'x8'
2-8'x7'
20
10
7
7
90
56
7
LINE E
LINE G
6.5
Extend Line G to Open
Space & grade to drain1661 _
5228 451 Added 8500
R/W Take (ac)
R/W Cost
3.5 12.5 30.2
($100,000 /ac)$350,000 $
$
$
1,250,000
9,236,689
8,196
$3,020,000
11,806,000
10,476
Total Cost
MDP Fee
$ 17,136,561 $
$$15,205
Alternative 1 are all RCB, may require less R/W take if alignment is within the roadway, assume 50% o fthe alignment within Street R/W
Alternative 2 are concrete trap channel, assume roadway/ channel crossing at 4 locations, channel transition to RCB at crossings
Alternative 3 are earth trap channel, assume roadway/ channel crossing at 4 locations, channel transition to RCB at crossings
*East Lake Zone Total Area = 2751 Ac, Exclude Summerly Development and all Open Space Areas, Net Area = 1127 Ac
Conclusions
The above alternatives and their associated costs were presented to the City Engineer and stake
holders for consideration. Even though the open channel alternatives are less costly, they can be
unsightly, aesthetically unpleasing, have a higher maintenance cost, less safe for the public
compared to the underground facilities, and dissect the land and post more restrictions to the
future developments. The City considers utilizing RCB for Line E-1 and Line E-2 as the most
viable alternative for the East Lake Zone.
It is important to understand that the proposed East Lake MDP facilities alone will not adequately
protect the area from flood hazards, unless either the upstream facilities per the Wildomar MDP
are in place to collect and convey the storm flow to the designated connection points or the interim
intercepting / collecting facilities are constructed to serve the same purposes.
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Existing West Elsinore MDP and ADP
“West Elsinore Master Drainage Plan” and “West Elsinore Area Drainage Plan” were
prepared by Riverside County Flood Control and Water Conservation District (District), with the
Area Drainage Fee approved in 1986 and updated in June 12, 1993. The drainage area covered
by this MDP consists of approximately 10.5 square miles, where nearly 40% of the drainage area
is within the City boundary. Currently, most of the MDP facilities are constructed, and areas within
the city boundary are mostly developed, except the steep hillside area.
Figure 4-5
West Elsinore MDP
The MDP update does not propose any change to the existing West Elsinore MDP. However,
since the ADP fee was last updated in June of 1993, an adjustment to the current construction
cost index is warranted.
According to the Engineering News Record published Construction Cost (LA) Price Index Value,
for September 2021, Index Value is 13,212.48; for June 1993, Index Value is 6,426.76. The
increase on cost is 1.735. Therefore, ADP fee of $ 5,567/ac in 1993 will be adjusted to $ 11,445/ac
as of September 2021.
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SECTION 5 - ENVIRONMENTAL CONSTRAINTS
Background
The primary purpose of the MDP update is to identify engineering solutions that will control
flooding and drainage problems within the City. In addition, the MDP identifies potential locations
for future water quality treatment facilities, estimates the cost of facilities, and identifies funding
sources to facilitate orderly and economically-prudent development of the area.
This section serves as a general overview of the environmental setting of the MDP area as well
as a review of some of the environmental analyses and documentation that may be required. The
intent of this chapter is to inform the decision-making process of siting MDP facilities so that
environmental constraints can be identified and ideally, avoided.
It should be noted that individualized analysis on a project-by-project basis pursuant to
the regulations at the time, will be necessary once specific facility sites have been
identified to determine the site-specific environmental constraints.
Aesthetics
The City’s most notable aesthetic resource is Lake Elsinore itself, a 3,000-acre natural lake. This
large, shallow, natural Lake is the terminus of the San Jacinto River. As development in the region
increased over the past 100 years, Lake Elsinore and the many hot springs around the Lake
became popular recreation destinations. During the peak of initial settlement in the region and
recreational development at Lake Elsinore, Federal and State agencies, as well as private groups
stocked a wide variety of fish species in the lake with the goal of drawing people to Lake Elsinore
by providing recreational fishing opportunities. The City’s aesthetic setting is characterized by
urbanized development of various densities occurring within varied topographical features and
interspersed with open space areas.
Scenic resources within and surrounding the City include the Cleveland National Forest (Santa
Ana Mountains) that defines the westerly boundary with beautiful, rugged hillsides, canyons, and
rocky outcroppings. Distant ridgelines of Mt. San Antonio and Mt. San Gorgonio as well as open
space around Temescal Creek and the Gavilan Hills Plateau are aesthetically important.
The California Department of Transportation (Caltrans) currently identifies both Interstate 15 and
State Route 74 as eligible for listing as State Scenic Highways, but they are not officially
designated as such (Lake Elsinore General Plan FEIR).
Components of the proposed MDP could potentially affect scenic vistas and other scenic
resources within the project area. The open channels, debris basins on the hillsides, and water
quality basins could be visible and could have an effect on a scenic vista, which would require
analysis and consideration. Although underground drainages would not be visible after
construction is completed, construction debris, and construction equipment may temporarily affect
the aesthetic quality of the immediate area. Therefore, depending on where future drainage
facilities are located, there could be aesthetic impacts that would need to be evaluated on a
project-by-project basis.
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Air Quality
The proposed MDP area is located within the South Coast Air Basin (SCAB), which encompasses
all of Orange County and portions of Los Angeles, San Bernardino, and Riverside Counties. The
SCAB is under the jurisdiction of the South Coast Air Quality Management District (SCAQMD).
The Climate Action Plan (CAP) is the City of Lake Elsinore’s long-range plan to reduce local
greenhouse gas emissions that contribute to climate change. The CAP identifies the activities in
Lake Elsinore that generate greenhouse gas emissions, quantifies these emissions, and projects
their future trends. It also describes local greenhouse gas emissions targets for the years 2020
and 2030, consistent with the State of California’s emission-reduction targets, as well as
strategies and measures to meet these targets.
As each component of the MDP is designed, appropriate project-specific analyses of air quality
impacts and greenhouse gas emissions during both construction and operational phases may be
needed.
Biological Resources
Approximately 16 different natural vegetative communities occur in the City and its SOI. In
addition, 19 plants and a minimum of 38 animals within the City and/or the SOI’s habitats are
accorded the “special status” designation because they are unique, have relatively limited
distribution in the region, or have high wildlife value as defined by Federal, State, and local
government conservation programs.
Lake Elsinore is a signatory to the Joint Powers Agreement that governs the Regional
Conservation Authority that oversees the Western Riverside County Multiple Species Habitat
Conservation Plan (MSHCP). The proposed MDP area is within the Elsinore Area Plan, Mead
Valley Area Plan, and Lake Mathews/Woodcrest Area Plan of the MSHCP, including many
portions within criteria cells. As each component of the MDP is designed, appropriate project-
specific analyses of biological resources and project impacts during both construction and
operational phases, may be needed. The proposed MDP zones contain MSHCP Criteria Cells,
burrowing owl survey areas, and narrow endemic plant survey areas as shown in Figure 5-1.
Preparation of a General Habitat Assessment, MSHCP Consistency Analysis, Determination of
Biologically Equivalent or Superior Preservation (DBESP) report, Focused Surveys,
Presence/Absence Surveys, and/or Pre-Construction Clearance Surveys may be required as the
MDP is constructed, depending on the site-specific circumstances.
The proposed MDP area northeast of Lake Elsinore falls within the Stephens’ kangaroo rat (SKR)
Fee Area outlined in the Riverside County SKR Habitat Conservation Plan (HCP), which includes
fees pursuant to County Ordinance 663.10 for the SKR HCP Fee Assessment Area as established
and implemented by the County of Riverside.
5-55
Figure 5-1
MSHCP Criteria Cells and Survey Areas and SKR fee area
Cultural Resources
Archaeological resources are defined as the material remains of an area’s prehistoric
(aboriginal/Native American) or historical (European or Euro-American) human activity.
Archaeological resources are recognized as non-renewable resources significant to our culture
and are afforded protection by Federal and State law primarily through conformance with the
California Environmental Quality Act (CEQA).
The Riverside County paleontological resources sensitivity mapping shows areas of high
paleontological sensitivity (“High A”) in Quaternary deposits north of Lake Elsinore along the west
side of the I-15 corridor (Figure 5-2). Another small strip of High A land is found along the I-15
corridor east of Lake Elsinore in the northeast portion of the East Lake Zone. The Temescal Wash
Zone contains a large portion of this High A land. Geologic formations or mapped rock units in
these areas may contain significant paleontological resources. These include rocks of Silurian or
Devonian age and younger that have potential to contain remains of fossil fish, and Mesozoic and
Cenozoic rocks that contain fossilized body elements and trace fossils such as tracks, nests and
eggs.
5-56
Figure 5-2
MDP Zone with Paleontological Sensitivity
The City of Lake Elsinore has also identified geologic units that are known to contain important
paleontological resources in the Alberhill Ranch area in the northwest portion of the City, and
within the Temescal Wash Zone of the proposed MDP. In this localized area, the Silverado
Formation of Paleocene age (approximately 66 to 55 million years old) is considered highly
sensitive for invertebrate and plant material. The fossil plants from this unit have been studied for
more than half a century.
Historical sites from mining, transportation, recreation, and ranching/homesteading sources are
represented throughout the proposed MDP area. The number of previously identified historical
sites is much smaller than prehistoric sites making it more difficult to determine areas of known
or established sensitivity.
Construction and operation of any MDP facility would be required to comply with State law about
accidental findings of human remains per State Health and Safety Code §7050.5. If human
remains are encountered during construction, no further disturbance shall occur until the
Riverside County Coroner has made a determination of origin and disposition pursuant to Public
Resources Code §5097.98. If the County Coroner determines that the remains are not historic,
but prehistoric, the Native American Heritage Commission must be contacted to determine the
most likely descendent for this area. Once the most likely descendent is determined, treatment of
the Native American human remains will proceed pursuant to Public Resources Code 5097.98
(Lake Elsinore General Plan FEIR, RCIP).
As each component of the MDP is designed, appropriate project-specific analyses of cultural
resources and project impacts during both construction and operational phases, may be needed.
Compliance with Assembly Bill 52 (AB 52), which requires tribal consultation may also be
required.
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Geology and Soils
The MDP area is located within a seismically-active region of California. Fault zones affecting the
MDP area include the San Andreas, San Jacinto, Elsinore, and Cucamonga Fault Zones. The
following types of ground failure could occur within the City of Lake Elsinore, its SOI, and the
proposed MDP area due to seismic activity: fault rupture, seismic ground shaking, liquefaction,
lateral spreading, ground lurching, and seismically-induced ground settlement (Lake Elsinore
General Plan FEIR).
The area also is susceptible to geologic hazards. Development along hillsides is particularly
susceptible to landslides, as they are considered to be a basic geologic hazard for such
development. Expansive soils are often associated with geologic units having marginal stability
and can occur in low-lying alluvial basins, as well as along hillside areas. Such soils are known to
exist in the City and its SOI and therefore may be present within the proposed MDP area. Soil
corrosion is a complex phenomenon, with a number of variables involved. The City of Lake
Elsinore requires testing for corrosive soils as part of the soils and geotechnical reporting
demanded of all new construction projects. Subsidence is often caused by the overdraft of
groundwater aquifers, and in the Elsinore Valley, subsidence has been attributed to groundwater
pumping.
As each component of the MDP is designed, appropriate project-specific analyses of geologic
conditions and project impacts during both construction and operational phases, may be needed.
Project-specific geotechnical investigations would likely be required to provide design
recommendations to construct with consideration of any geologic constraints.
Hydrology and Water Quality
The proposed MDP is within the San Jacinto River sub-watershed of the larger Santa Ana River
watershed. The primary natural surface water features within the City planning area are Lake
Elsinore, the San Jacinto River, and Temescal Wash. Railroad Canyon Reservoir (aka Canyon
Lake)—a manmade facility— infrequently releases flows to the San Jacinto River, which then
discharges intermittently into Lake Elsinore. During periods of high water elevations, Lake
Elsinore discharges into Temescal Wash that flows north and eventually connects with the Santa
Ana River.
The Elsinore groundwater basin is primarily supplied by infiltration of rainfall in the surrounding
watershed. Other sources of inflow include infiltration along the San Jacinto River channel
upstream of Lake Elsinore and agricultural and residential return flows. Municipal pumping for
potable water is the only major outflow from the Elsinore groundwater basin.
A primary purpose of the proposed MDP is to outline engineering solutions to mitigate flooding in
the City of Lake Elsinore and SOI. As each component of the MDP is designed, appropriate
project-specific analyses of hydrologic conditions and project impacts to water quality during both
construction and operational phases, may be needed. Project-specific hydraulic and/or hydrology
studies would likely be needed.
The State Water Resources Control Board, in compliance with Clean Water Act Section 303(d),
maintains a list of impaired waterbodies. Lake Elsinore is listed due to the presence of four
constituents: high nutrient levels from unknown point sources, organic enrichment/low dissolved
5-58
oxygen from unknown point sources, sedimentation/siltation from local urban runoff and storm
sewers, and toxicity from unknown non-point sources. Fluctuating water levels in Lake Elsinore
and algal blooms triggered by excess nutrients and low dissolved oxygen concentrations have
impaired the ecology and recreational use of Lake Elsinore. The source of the sedimentation and
siltation within the lake are from urban runoff and stormwater. According to the Regional Water
Quality Control Board (RWQCB), improvement to the water quality in the lake can only be
achieved through water quality monitoring and restoration programs. Some of the future MDP
facilities are anticipated to ameliorate the ongoing water quality concerns in the Lake Elsinore
watershed. As each component of the MDP is designed, appropriate project-specific analyses of
potential discharges of pollutants during both construction and operational phases, may be
needed.
Wetlands
Wetland and riparian/riverine features in the study area include Lake Elsinore (located in the
south-central portion of the City), the Temescal Wash, and the San Jacinto River. In addition, the
area contains numerous smaller ephemeral drainages, washes, ditches, creeks, springs, areas
of perched water and scattered vernal pools. Many of these resources are not located within
MSHCP criteria cells and may or may not be associated with sensitive species and/or distinctive,
“high-value” habitat. Wetland, riparian and riverine areas are addressed by the MSHCP, and
regulated by the RWQCB, California Department of Fish and Wildlife, and the U.S. Army Corps
of Engineers.
Impacts to wetlands or Waters of the U.S./State from proposed MDP facilities should be
minimized, if not avoided, to the extent practicable. Otherwise, permanent impacts to jurisdictional
waterways that require regulatory permits would require mitigation. Determining adequate
methods of providing mitigation should be done as early as possible in the project development
process. Depending on the site, mitigation can be provided by local mitigation banks and in-lieu
fee programs. Drainages and wetlands that may be subject to these regulations are shown in
Figure 5-3.
Figure 5-3
MDP Zones with Wetland and “Blue Line” Streams
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As each component of the MDP is designed, appropriate project-specific analyses of wetlands
and/or riparian/riverine areas that may or may not be jurisdictional to regulatory agencies during
both construction and operational phases, may be needed. In addition, jurisdictional delineations
may be needed to determine the limits of regulatory oversight for impacts to Waters of the U.S.
and/or Waters of the State.
Other Environmental Considerations
As each component of the MDP is constructed, consideration may be needed for one or more of
the following topics during project design:
•
•
•
•
•
•
•
•
•
•
Agriculture and Forest Resources;
Hazards and Hazardous Materials;
Land Use and Planning;
Mineral Resources;
Noise;
Population and Housing;
Public Services;
Recreation;
Traffic and Transportation; and/or
Utilities and Service Systems.
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References
City of Lake Elsinore, The City of Lake Elsinore General Plan, Adopted December 13, 2011. (Available at
http://www.lake-elsinore.org/index.aspx?page=909, accessed on February 18, 2016.)
City of Lake Elsinore, Final Recirculated Program Environmental Impact Report, Certified on December
13, 2011. (Available at http://www.lake-elsinore.org/index.aspx?page=913, accessed on February 18,
2016.)
City of Wildomar, Draft General Plan Update, January 2015. (Available at http://wildomargp.org/,
accessed February 18, 2016.)
County of Riverside,Elsinore Area Plan,November 2014.(Available at
http://planning.rctlma.org/ZoningInformation/GeneralPlan.aspx, accessed February 18, 2016.)
County of Riverside, Riverside County Integrated Project General Plan, Adopted October 7, 2003.
(Available at http://planning.rctlma.org/ZoningInformation/GeneralPlan.aspx , accessed on February
18, 2016.)
County of Riverside, Riverside County Land Information System (RCLIS), (Available at
http://mmc.rivcoit.org/MMC_Public/Viewer.html?Viewer=MMC_Public , accessed on February 18,
2016.)
Prepared by:
Albert A. Webb Associates Planning & Environmental Services Department
Autumn DeWoody, Associate Environmental Analyst
Jillian Feyk-Miney, Assistant Environmental Analyst
5-61
SECTION 6 - COST SUMMARY AND FUNDING MECHANISMS
Cost Summary
Probable cost estimates were prepared as part of the MDP. A cost summary for the MDP facilities
is shown in table below. The estimated costs were based on the ENR Index adjustment and 2021
Planning Cost Sheets of the District. The components of the cost include construction, right-of-
way acquisition, 22% of lump sum items such as mobilization, water control, traffic control, etc.,
12% of contingencies and 28% of combined engineering, administration and mitigation.
Lake Elsinore Master Drainage Plan Facility Cost Summary
Administration,
Engineering,
Mitigation (28%)
Construction
Total
Debris Basin Right-of-Way
(2) (3)Zone Subtotal (1)Total(4)
Alberhill Sub Zone
Temescal Wash
Lake Zone
$44,734,005
22,164,010
23,070,480
16,418,696
$
$
$
$
12,525,521
6,205,923
6,459,734
4,597,235
$
$
$
$
57,259,526 $ 6,720,535 $ 2,020,215 $
$
$
$
66,000,276
31,135,562
32,421,846
21,431,931
$
$
$
28,369,933 $ 2,425,114
29,530,214 $ 1,966,631
$
$
$
340,515
925,000
416,000East Lake Zone
West Elsinore
21,015,931 $-
City Total $106,387,190 $29,788,413 $ 136,175,603 $ 11,112,281 $ 3,701,730 $ 150,989,614
(1) Cost based on RCFC&WCD 2021 Cost Project Planning Costs Worksheet
(2) Estimated cost based on average from Lakeland Village MDP
(3) $100,000 per acre Raw Land Cost for Right-of-Way cost
(4) Total Construction Cost with Eng & Admin and Debris Basins
The estimated costs for each zone or sub-zone are listed below:
East Lake Zone
MDP East Lake Zone Cost Summary
Facility Subtotal Debris Basin Right-of-Way Total
Line E-1
Line E-2
Line E-3
Line E-4
$ 14,334,822
$ 4,569,680
$
$
300,000 $ 14,634,822
116,000 $ 4,685,680
$958,377 $
$
958,377
$ 1,153,052 1,153,052
Total $ 21,015,931 $- $416,000 $ 21,431,931
6-62
Alberhill Sub-Zone
MDP Temescal Wash Zone - Alberhill Sub-Zone Cost Summary
Facility Subtotal
363,857
Debris Basin Right-of-Way Total
Line A01
Line A02
Line A03
Line A04
Line A05
Line A06
Line A07
Line A08
Line A09
Line A10
Line A11
(DB -1&2)/2 (1)
$$
$
$
$
$
$
$
$
$
$
$
$
363,857
3,653,329
892,208
$
$
$
$
$
$
$
$
$
$
2,720,342
892,208
$
$
707,987 $
$
225,000
24,535,817
17,649,039
1,882,036
496,326
4,830,047 1,748,700 31,114,564
17,649,039
1,882,036
496,326
4,942,342
1,677,064
1,731,813
368,682
4,942,342
1,677,064
1,731,813
368,682
$1,182,501 $46,515 1,229,016
Total $57,259,526 $6,720,535 $2,020,215 $66,000,276
(1) the Cost of Debris basins 1 & 2 is shared between Alberhill Sub-Zone and Temescal Zone
Temescal Zone
MDP Temescal Wash Zone Cost Summary
Facility
Line T-1
Subtotal
3,869,694
Debris Basin Right-of-Way Total
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
3,869,694
5,412,255
1,723,459
195,547
Line T-2 5,412,255
1,723,459
195,547
641,847
518,613
291,522
432,133
12,802,781
2,482,083 $
$
Line T-3
Line T-4
Line T-5 641,847
Line T-6 518,613
Line T-7 291,522
Line T-8 432,133
Line T-9 12,802,781
2,651,514
1,225,883
1,370,316
Line T-10
DB -5
133,731 $35,700
258,300
46,515
967,583 $
(DB -1&2)/2 (1)$1,323,801 $
Total $28,369,933 $2,425,114 $340,515 $31,135,562
(1) the Cost of Debris basins 1 & 2 is shared between Alberhill Sub-Zone and Temescal Zone
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Lake Zone
MDP Lake Zone Cost Summary
Subtotal Debris Basin Right-of-WayFacility Total
Line L-1 to L-5
Line L-6
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
2,268,771
1,235,007
2,308,851
534,736
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
2,268,771
1,235,007
2,308,851
534,736
Line L-7
Line L-8, L-9
Line L-10
Line L-11
Line L-12
Line L-13
Line L-14
Line L-15
Line L-16
Line L-17
Line L-18
Line L-19
Line L-20
Line L-21
Line L-22
Line L-23
1,342,502
1,300,098
1,251,734
1,139,857
3,339,916
937,746
1,342,502
1,300,098
1,251,734
1,139,857
3,739,916
937,746
$400,000
4,669,989
290,081
4,669,989
290,081
2,775,166
976,019
2,775,166
976,019
666,518 666,518
527,623 527,623
3,415,709
549,890
$1,966,631 $525,000 5,907,341
549,890
Total $ 29,530,214 $1,966,631 $925,000 $ 32,421,846
Debris Basin and Detention Basin
Drainage Drainage Debris R/W Area
(1)
Constr CostDebris Basin R/W Cost Total CostSytem
(name)
-
Area
(ac)
Vol
(ac-ft)
18.7
25.6
12.3
76.0
9.0
Total (2)
($)(name)
DB1
(ac)($100,000/ac)($)
949 3.93
5.38
2.58
15.96
1.89
11.49
1.41
0.36
5.25
9.30
4.65
$
$
$
392,700 $ 1,078,340
537,600 $ 1,476,231
$
$
$
$
$
$
$
$
$
$
$
1,471,040
2,013,831
967,583
5,978,560
707,987
4,302,990
527,057
133,731
1,966,631
2,647,601
1,323,801
DB2 -1425
822DB5-258,300 $709,283
DB6 Line L14
Line A02
Line A04
Line A04
5133
362
$ 1,596,000 $ 4,382,560
189,000 518,987
$ 1,148,700 $ 3,154,290
DB8 $$
DB9 1838
293
54.7
6.7DB9A $
$
$
$
$
140,700
35,700
$
$
386,357
98,031DB10 Line T10-01
DB11 (3) Line L22
131 1.7
497 25.0
44.3
22.2
525,000 $ 1,441,631
93,030 $ 2,554,571
46,515 $ 1,277,286
(DB1 &2) (4)2374
1187(DB1 &2)(0.5)
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(1) Estimated R/W needed based on average from Lakeland MDP at 0.21 acre per each ac-ft debris volume
(2) Estimated cost based on average from Lakeland Village MDP dated in May, 2016. ENR Construction Price Index of
1.185 is used to adjust construction cost to September, 2021
(3) Estimated detention storage volume needed
(4) DE1 & DB2 cost to be shared by Alberhill Sub-zone and Temescal Wash Zone 50/50
ADP Fees
An area drainage fee is a financing mechanism used to offset taxpayer costs for proposed
drainage facilities. The fees are imposed on new development within the plan area. The
Subdivision Map Act and AB1600 requires that agencies imposing fees have a general drainage
plan for the fee area, a special fund for the fees and an equitable distribution of the fees prior to
implementation.
ADP fees are established using the MDP facility cost for each zone and distributed to the
developing areas. The open spaces and areas already developed and build out or “near build out”
are exclude from the ADP fee calculations.
Lake Elsinore Area Drainage Fee Summary
MDP Zone AreaZoneMDP Cost Total Area Drainage Fee(Acres)
Alberhill Sub Zone
Temescal Wash
Lake Zone
$
$
$
$
66,000,276
31,135,562
32,421,846
21,431,931
2272
2451
3340
1127
$
$
$
$
$
29,049
12,703
9,707
East Lake Zone
West Elsinore
19,017
11,445
City Total $ 150,989,614
GIS Data Base
Utilizing and developing the GIS data base is an integrated and essential part of the MDP
developments.
Throughout the MDP update process, Webb’s GIS experts have been facilitating and supporting
the MDP study effort. GIS Data Collector was created and utilized for geo-referencing locations
and facilities of field investigation photos and field notes. A base map for the MDP was created
utilizing City’s topographic contours, the Districts contours and GIS data base for parcels,
General Plan Land Use and existing drainage facilities.
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New feature classes for MDP boundaries, drainage fee areas, known drainage issue locations,
and SD inlet locations were created and will be added to City’s Storm Drain geodatabase as a
new Feature Dataset.
Additional Funding Sources
The Area Drainage Fees established hereon will be imposed on the development projects in
connection with conditions of approval of the projects as the Drainage Mitigation Fee.
In addition to ADF, other funding sources maybe available to the community for flood protections,
water quality mitigation and ground water recharge.
FEDERAL PROGRAMS
Economic Development Administration, Public Works and Economic Adjustment
Assistance Program
“This program provides assistance to help distressed communities attract new industry,
encourage business expansion, diversify local economies, and generate long-term, private sector
jobs. Among the types of projects funded are water and sewer facilities, primarily serving industry
and commerce; access roads to industrial parks or sites; port improvements; business incubator
facilities; technology infrastructure; sustainable development activities; export programs;
brownfields redevelopment; aquaculture facilities; and other infrastructure projects. Specific
activities may include demolition, renovation, and construction of public facilities; provision of
water or sewer infrastructure; or the development of storm water control mechanisms (e.g., a
retention pond) as part of an industrial park or other eligible project.”
Website: https://www.eda.gov/funding-opportunities/
Federal Emergency Management Agency (FEMA), Flood Mitigation Assistance Program
This program has “the goal of reducing or eliminating claims under the National Flood Insurance
Program (NFIP).”
Website: https://www.fema.gov/flood-mitigation-assistance-grant-program
Federal Emergency Management Agency (FEMA), Pre-Disaster Mitigation Program
This program provides assistance to implement a sustained pre-disaster natural hazard mitigation
program to reduce overall risk to the population and structures from future hazard events, while
also reducing reliance on Federal funding in future disasters.
Website: https://www.fema.gov/pre-disaster-mitigation-grant-program
6-66
National Fish and Wildlife Foundation, Environmental Solutions for Communities
The program supports “projects that link economic development and community well-being to the
stewardship and health of the environment. This 5-year initiative is supported through a $15
million contribution from Wells Fargo that will be used to leverage other public and private
investments with an expected total impact of over $37.5 million. Funding priorities for this program
include: (1) supporting sustainable agricultural practices and private lands stewardship; (2)
conserving critical land and water resources and improving local water quality; (3) restoring and
managing natural habitat, species and ecosystems that are important to community livelihoods;
(4) facilitating investments in green infrastructure, renewable energy and energy efficiency; and
(5) encouraging broad-based citizen participation in project implementation.”
Website: http://www.nfwf.org/environmentalsolutions/Pages/home.aspx
U.S. Department of Housing and Urban Development, Community Development Block
Grants/Entitlement Grants
“The objective of this program is to develop viable urban communities, by providing decent
housing and a suitable living environment, and by expanding economic opportunities, principally
for persons of low and moderate income. Recipients may undertake a wide range of activities
directed toward neighborhood revitalization, economic development and provision of improved
community facilities and services.”
Website:
http://portal.hud.gov/hudportal/HUD?src=/program_offices/comm_planning/communitydevelopm
ent/programs
U.S. Department of the Interior, Cooperative Watershed Management Program
The goal of the program “is to enhance water conservation, including alternative uses; improve
water quality; improve ecological resiliency of a river or stream; and to reduce conflicts over water
at the watershed level by supporting the formation of watershed groups to develop local solutions
to address water management issues.”
Website: http://www.usbr.gov/watersmart/cwmp/
U.S. Environmental Protection Agency, Clean Water State Revolving Fund
The fund “provides a permanent source of low-cost financing for a wide range of water quality
infrastructure projects. These projects include municipal wastewater treatment and collection,
nonpoint source pollution controls, decentralized wastewater treatment systems, green
infrastructure, estuary management.”
Website: https://www.epa.gov/cwsrf
6-67
STATE PROGRAMS
California Department of Water Resources, Flood Control Subventions Program
This program “provides financial assistance to local agencies cooperating in the construction of
federally authorized flood control projects.”
Website: http://www.water.ca.gov/floodmgmt/funding/subventions.cfm
California Department of Water Resources, California Safe Drinking Water Bond Law of
1988
This program provides “loans and grants to water systems with projects that help to meet Safe
Drinking Water Standards. Such projects include planning, water conservation, water loss
detection, capital improvements, and corrosion control.”
Website: http://water.ca.gov/grantsloans/grants/prop81sdw/index.cfm
California State Water Resources Control Board, Clean Water State Revolving Fund
Program (CWSRF)
This program assists in financing projects which include, but are not limited to the construction of
publicly-owned treatment facilities, such as: wastewater treatment, local sewers, sewer
interceptors, water reclamation and distribution, storm water treatment, combined sewers, and
landfill leachate treatment.
Website: http://www.waterboards.ca.gov/water_issues/programs/grants_loans/srf/index.shtml
California State Water Resources Control Board, Drinking Water State Revolving Fund
Program (DWSRF)
This program funds the planning/design and construction of drinking water infrastructure projects
including: treatment systems, distribution systems, interconnections, consolidations, pipeline
extensions, water sources, water meters, and water storages.
Website: http://www.waterboards.ca.gov/drinking_water/services/funding/SRF.shtml
California State Water Resources Control Board, Storm Water Grant Program (SWGP)
The program promotes the beneficial use of storm water and dry weather runoff by funding storm
water and dry weather runoff projects advancing water quality and realizing multiple benefits from
the storm water and dry weather runoff as a resource.
6-68
Website: http://www.waterboards.ca.gov/water_issues/programs/grants_loans/swgp/
California Infrastructure and Economic Development Bank (I-Bank) State Revolving Fund
(ISRF) Loan Program
The program provides a loan program for infrastructure projects and economic expansion
projects. Infrastructure projects include city streets, county highways, drainage, water supply and
flood control, educational facilities, environmental mitigation measures, parks and recreational
facilities, port facilities, power and communications, public transit, sewage collection and
treatment, solid waste collection and disposal, water treatment and distribution, defense
conversion, public safety facilities, state highways, military infrastructure, and goods movement-
related infrastructure.
Website: http://www.ibank.ca.gov/infrastructure_loans.htm
LOAN FINANCING PROGRAMS
Pay-as-you-go
“Under a pay-as-you-go approach, revenues from impact fees would generate funding for
construction. Impact fees would be collected and deposited in a special fund until enough money
accumulates to begin a construction project. The size of the construction outlay may make pay-
as-you-go a difficult approach or, at a minimum, require project phasing and supplementary
funding from other sources. A drainage fee per acre (developer impact fee) could be established
for new development or redevelopment projects for this purpose. The impact fee amount would
be regulated by Section 66000 of the California Government Code, which governs impact fees
relative to not being more than the costs that can be attributed to each new user.”
Assessment Districts
“Assessment Districts formed under the conventional statutes (Improvement Acts of 1911,
Municipal Improvement Act of 1913, and the Improvement Bond Act of 1915) provide some of the
less costly financing available because of the real estate security. Assessment districts do not
require a vote, but do require notice and a protest at a required hearing by more than 50 percent
of the property owners within the proposed district can stop the proceedings. Assessment districts
can be initiated by a petition of property owners or by City Council action. Only improvements that
provide a special benefit to properties can be assessed to a property. Improvements that provide
a general regional benefit to property outside the district would not be eligible to be included in an
assessment district or would have to be funded by contributions outside the assessment district.”
6-69
SECTION 7 - CONCULSIONS AND RECOMMENDATIONS
Conclusions and Recommendations
Based on the studies and investigations made for this report, it is concluded that:
1. The City of Lake Elsinore has experienced serious flooding problems in the past. As the
City continues to urbanize, the risk of flood damage is expected to increase unless the
flood protection and drainage facilities identified in the report are constructed in an orderly
manner.
2. A drainage system is required to safely convey stormwater runoff through the City with the
least interruption to public services. The MDP presented in this report is such a system
and is deemed the most feasible of the alternatives studies.
3. The proposed MDP lends itself to staged construction as funds become available.
4. The proposed MDP offers a comprehensive long-term plan to provide stormwater facilities
that are necessary to protect life and property from flood hazards in the City.
5. The total cost of the recommended improvements, including construction, right-of-way
acquisition, engineering, administration, and contingencies is estimated to be $
150,990,000.
It is recommended that: the Master Drainage Plan be updated and Area Drainage Fees for each
MDP zone, as set forth herein, be adopted by the City Council and be used as a planning level
guide for future developments in the study area.
Implementation of the above recommendations will provide the City of Lake Elsinore with a
properly functioning storm drain system.
Future Growth of the City
Future growth of the City may be reflected in many aspects, such as an increase in the population;
amendment of the approved specific plans; change of land use; change of development densities;
filing and approval of the new specific plans and tentative tract/ parcel maps and expanding of
the city boundary through the annexation process. Since this report is based on the current land
use and city boundary, land use change and new annexations will have an impact on the MDP
and ADF. When these impacts become significant, the City shall develop the ADF policies for the
newly annexed properties or conduct a new MDP update or partial update to accommodate the
changes.
7-70
Limitations
The hydrologic analysis presented herein has been prepared in accordance with guidelines
established by the District. The design criteria established for this study were discussed with the
City and pre-approved by the Interim City Engineer.
This document has been prepared at a level of detail appropriate for the scope of work. The
methodology employed in the analysis was selected as suitable for the characteristic of the
watershed; designated land use and proposed developments and existing drainage infrastructure.
Our field investigation identified current flooding issues and deficiencies. This report presents
some short term solutions and future drainage improvements to alleviate flooding.
The MDP facilities described herein are conceptual in nature. The MDP provides a conceptual
solution that addresses drainage problems within the City based on various engineering,
environmental and economic considerations. By no means does the MDP represent the only
feasible solution. The alignment and location of the facilities proposed in this report are general.
Precise facility locations will be dictated by conditions and other factors existing at the time of
design. More detailed analysis performed at the design stage will determine final facility sizing.
The use of this document is limited to addressing the purpose and scope previously defined by
the City of Lake Elsinore. The analyses presented in this report are not intended to be used for
the detailed design. Webb shall not be held responsible for any unauthorized application of the
report and the contents herein.
The opinions and conclusions presented in this report have been derived in accordance with the
current standards of civil engineering practice, and from information and concurrence provided
by the City of Lake Elsinore. No other warranty is expressed or implied.
7-71
APPENDIX A - Field Investigation Report
7-72
CITY OF LAKE ELSINORE MDP
Field Investigation Report
(CIP Project No. 120)
Prepared for:
Prepared by:
October, 2016
i
TABLE OF CONTENTS
SECTION 1 - INTRODUCTION....................................................................................1-1
Methodology _________________________________________________________ 1-1
SECTION 2 - DRAINAGE ISSUES..............................................................................2-2
Drainage Issue Locations _______________________________________________ 2-2
Drainage Issue General Remedies________________________________________ 2-9
SECTION 3 - DRAINAGE INLETS AND OUTLETS....................................................3-1
Field Review _________________________________________________________ 3-1
SECTION 4 - RECOMMENDATIONS..........................................................................4-1
ii
SECTION 1 - INTRODUCTION
This field report for the Lake Elsinore Master Drainage Plan is intended to provide a
comprehensive overview of the existing drainage issues and drainage facilities located within
the City of Lake Elsinore (City). The drainage issues include street and private property flooding,
erosion, long-term ponding, drainage facility maintenance issues, and hillside runoff. The
drainage facilities include City-owned storm drains and channels, Riverside County Flood
Control District-owned storm drains and channels, homeowner association-owned basins, and
the inlets and outlets associated with each. The field surveys and documentation provided in
this report were collected from January to March 2015.
¢ Methodology
Most of the drainage issue locations and drainage facility locations were identified by City staff
prior to the field surveys. The drainage issue locations were collected by City maintenance and
engineering staff based on past resident complaints and prior knowledge and experience in the
area. The type and location of various storm drain facilities are based on as-built plans in the
City’s possession. The locations were input into an electronic map using GIS software to keep
collected information easily accessible. During the field surveys, all notes and pictures were
collected using the ArcGIS Collector mobile application. This application operates on any mobile
phone or data-enabled tablet and uploads information to the GIS map in real-time.
All of the field surveys were conducted by at least one engineering staff member from Albert A.
Webb Associates (Webb) along with at least one engineering staff member from the City.
1-1
SECTION 2 - DRAINAGE ISSUES
¢ Drainage Issue Locations
Webb surveyed and documented approximately 79 drainage issue locations. These locations
are characterized by any combination of street flooding, private property flooding, dirt or
roadway erosion, long-term ponding, hillside runoff, and maintenance issues. Nearly all of the
drainage issue locations are located between Interstate 15 and the northeast side of the lake.
The northeast side of the City is largely an older area and there are few to no storm drain
facilities. There are also several hilly areas in the area that seem to exacerbate the flooding and
runoff problems. Figure 1 shows the locations of observed drainage issues throughout the City.
Figure 1
City of Lake Elsinore Drainage Issue Locations
2-2
•Street Flooding. Street flooding in the City is primarily caused by low points in or near
the street. Although the climate is relatively arid, water often remains in the street for
days and even weeks after a rain event. This is especially true on gravel roads and on
streets with low points in or near dirt shoulders.
Image 1
Street and shoulder flooding on Collier Avenue near Chaney Street
Image 2
Street flooding on Lakeshore Drive at Matich Street
2-3
• Private Property Flooding. Private property flooding and water damage in the City
mainly occurs near hills and in areas of low elevations. Water often flows down hills or
streets and runs through or ponds in private property. This kind of flooding usually occurs
when property is at lower elevations than the street or when the street is lacking curbs or
berms to properly channelize the water.
Image 3
Private property at lower elevation than storm drain inlet on Heald Avenue
Image 4
Street flow on Ellis Street drains down slope into property at lower elevation
2-4
• Erosion. Street and dirt erosion is most commonly found on streets with no curb or berm
to properly channelize water. Water flows in the dirt at the edge of the street creating
ravines. This water can get underneath the street and cause pavement damage. Erosion
is also found wherever an undeveloped hillside meets a street. Dirt and debris from the
hill are carried by the water and are deposited on downstream streets and property.
Image 5
Dirt shoulder erosion adjacent to pavement on Franklin Street
Image 6
Dirt deposited at the low point at Main Street and Prospect Avenue
2-5
• Long-Term Ponding. Vacant lots and low-sitting gutter areas are susceptible to long-
term ponding. Vacant lots are undeveloped and are generally at lower elevations than the
surrounding streets and properties. Poorly designed, constructed, or maintained gutter
facilities also lead to long-term ponding. Similar to flooded streets, ponding can last for
days or weeks before completely evaporating. This can affect property access and
require constant maintenance.
Image 7
Overflow culvert discharges into vacant lot and nearby properties on Gunnerson Street
Image 8
Street low point in front of property at Sumner Avenue and Mohr Street
2-6
• Hillside Runoff. Runoff from the hills is one of the top drainage issues in the City. It
contributes a high volume of water into the City and usually carries dirt and debris. Some
hills are quite steep and the water runoff comes downstream with force. Dirt ravines and
erosion are far more likely to occur in the presence of high-speed water. Efforts to slow or
divert the hill runoff usually consist of sandbags which often break and require constant
maintenance.
Image 9
Sandbag placement on Chestnut Street to slow down runoff and catch debris
Image 10
Sandbag line on Bell Avenue to keep water from running into vacant lot
2-7
• Maintenance Issues. There are many locations that the City’s maintenance staff handles
on a regular basis. The staff places sandbags in runoff areas near hills, vacuums
problematic ponding areas, and clears runoff debris from streets and blocked storm
drains. Maintenance of drainage areas is constant and never-ending. During the field
surveys, staff noticed broken sandbags and blocked storm drains. The broken sandbags
are a constant maintenance item due to breakage and other damage that occurs during
rain events and daily use. The blocked storm drains seem to be neglected and have
heavy buildup of dirt, debris, and unchecked plant growth.
Images 11 and 12
Storm drain outlets blocked with dirt on Pierce Avenue and on Collier Avenue
2-8
¢ Drainage Issue General Remedies
Most of the drainage issues occur from only a few causes. The most common causes of the
surveyed drainage issue locations are low points on the street or property, lack of curbs and/or
gutter facilities, unimproved land, and insufficient maintenance of existing facilities.
Street flooding is often caused by streets not having proper slopes and crowns. Some streets in
the City were found to have low points within the traveled way. The slopes of the pavement can
be improved by paving, but care should be taken to not simply put the water on the shoulder of
the road. Water can often pond or erode dirt shoulders if not properly channelized.
The City uses a mix of asphalt concrete berm, curb, and curb/gutter combinations throughout
the City to help channelize water that runs off of the street. However, many locations simply
have dirt shoulders without any curb or gutter facility. This is leading to ponding, dirt erosion,
and dirt runoff. Constructing berms, curbs, and gutters can help channelize the water along the
street and towards storm drain facilities.
There are many vacant and unimproved lots and areas throughout the City. These unimproved
lots contribute to dirt runoff during rain events and often leave gaps in curbs, gutters, and other
drainage facilities when neighboring adjacent occupied properties. The City has been placing
sandbags to keep water draining along the street, but it is a temporary solution that often fails.
More permanent solutions such as berms, curbs, and gutters can be added to these lots to
assist in drainage. Also, the addition and preservation of grasses and other plants can reduce
the amount of water runoff and dirt erosion from these areas.
As stated in the next section, a survey of all known storm drain inlets and outlets larger than 36”
in diameter was conducted. Nearly all of the inlets and outlets surveyed had some kind of
blockage due to excessive sediment, debris, foliage, or a combination of the three. It is clear
that there was no regular maintenance for these facilities. An effort should be made to
completely clear all of the blocked inlets and outlets as the blockages cannot be cleared on their
own. In addition, regularly scheduled maintenance of the facilities should be done in order to
keep the facilities operating as intended.
2-9
SECTION 3 - DRAINAGE INLETS AND OUTLETS
¢ Field Review
Webb surveyed and documented approximately 109 inlet or outlet locations throughout the City
to verify size, location, and condition of each. Included in the survey are large culverts, weirs,
inlets and outlets in basins, and storm drain channels. Regarding inlets and outlets, Webb only
surveyed pipes 36” inches in diameter or larger to restrict the field review to only mainlines and
large pipes. The inlets and outlets were found evenly throughout the City. Figure 2 shows the
locations of surveyed inlets and outlets throughout the City.
Figure 2
City of Lake Elsinore Storm Drain Inlet and Outlet Locations
•Inlets and Outlets. Most of the inlets and outlets surveyed consist of a 36”+ diameter
pipe in a winged headwall configuration. The survey also found corrugated steel pipe
inlets in basins, low-lying areas, and at ends of small storm drain channels. The
condition of the inlets and outlets ranged from clean to completely blocked. As stated in
the previous section, many inlet and outlet locations are not well maintained which leads
to buildup of sediment and debris. The outlets also drain to a variety of different areas
including basins, dirt channels, rivers, and surrounding low-lying areas.
Image 13
3-1
Outlet Headwall in the Links at Summerly Golf Course
Image 14
Inlet Headwall with Debris Blockage near Canyon Ridge Drive
Image 15
3-2
Two Drain Inlets inside a Basin off Sugarbush Lane
Image 16
Corrugated Steel Pipe Outlet into Eroding Dirt Channel off Grunder Drive
Image 17
3-3
Storm Drain Inlet Under Construction at End of Open Channel near Obaria Way
Image 18
Storm Drain Inlet in a Detention Basin off Hermosa Drive
3-4
•Culverts. The survey found several large culverts throughout the City. Most consisted
of multiple large-diameter pipes. The culverts are found underneath roadways or are part
of overflow facilities in more remote locations. Most of the culverts are clear of debris
with the few exceptions with some degree of blockage. The culverts may be better
maintained than the inlets and outlets or experience less runoff.
Image 19
3x54” Culvert underneath Canyon Estates Drive
3-5
Image 20
3x48x96” Box Culvert underneath Grand Avenue
Image 20
Box Culvert underneath Collier Avenue with Sediment and Debris
3-6
•Weirs. The survey found many weirs in the City, most of which were overflow for
basins. Two other weirs stood out during the field review based on their size. All weirs
appeared to be in good condition.
Image 21
Overflow Weir on far side of Basin near 3rd Street
3-7
Image 22
Large Overflow Weir in McVicker Canyon
Image 23
Large Overflow Weir atop Culvert near Canyon Hill Community Park
3-8
•Basins. There are many storm water basins throughout the City. Most of the basins are
located in newly-developed residential areas where storm water treatment is required.
Nearly all of the basins are HOA-maintained. Generally, the basins include an inlet, an
outlet drain at higher elevation, and an overflow weir. Some of the basin inlets utilized
concrete velocity-reducing structures to reduce erosion while others utilized concrete
sediment trap basins. The basin outlets were usually vertical corrugated steel inlets
which allowed storm water to be stored in the basin until it reached the top of the outlet.
Many of the basins are clearly lacking routine maintenance as trees and an abundance
of other vegetative growth and debris have propagated in the basins. Routine
maintenance by the HOA or the City should be completed to keep the basins clear and
effective during storms.
Image 24
Concrete Inlet Structure into Basin near Acanthus Drive
3-9
Image 25
Raised Corrugated Steel Outlet Structure in Basin near Acanthus Drive
Image 26
Concrete Sediment Trap Inlet Structure in Basin near McVicker Canyon Park Road
3-10
•Channels. Most of the channels in the City are large structures built by the Riverside
County Flood Control and Water Conservation District (RCFCD). All of these channels
drain into or towards Lake Elsinore. The channels are either dirt-lined or concrete-lined.
Most of the channels are clear of debris. Some sediment and debris blockage can be
found near some of the inlets and outlets of the culverts. Figure 3 shows the locations of
the RCFCD lines.
Figure 3
Riverside County Flood Control and Water Conservation Distrct Facility Locations
3-11
Image 27
Sediment Buildup at Culvert Outlet at Grand Avenue
Image 28
Clean Trapezoidal Channel at Grand Avenue
3-12
Image 29
Dirt and Rock-Lined Channel at Lehr Drive
Image 30
Open Channel Area at Channel Split near Minthorn Street
3-13
Other Facilities. Two unique storm drain facilities were documented during the course
of the surveys. A rubber dam system was found in the Outlet Channel near Minthorn
Street and Wasson Channel at the high point of the Outlet Channel. Its purpose is to
direct the EVMWD recycled water either discharges into the Lake or to the Temescal
Wash for maintaining the water level of the Lake. This rubber dam system can be
inflated or deflated, and is a dry weather recharging system, not intended for flood
control purposes.
In addition, a large steel door (roughly 120” in diameter) covering a storm drain outlet
was found near Lakeshore Drive. It is thought that the door is to prevent high water in
the channel from flowing into the outlet pipe. The steel door may also force water to
drain slowly out of the outlet to reduce erosion in the San Jacinto River outlet area.
Image 31
Rubber Dam in Channel near Minthorn Street
Image 31 A
Rubber Dam in Outlet Channel near Minthorn Street
3-14
Image 32
Large Steel Door on Outlet near Lakeshore Drive
3-15
Image 33
RCFCD Arroyo Del Toro Channel near I-15 and Riverside Drive
3-16
SECTION 4 - RECOMMENDATIONS
Throughout the field surveys, it was increasingly obvious that routine maintenance of the storm
drain facilities, in general, was not being adequately performed. Many drainage issues could be
remedied or helped with proper maintenance of existing facilities. Even some HOA-maintained
facilities show a lack of regular, if any, maintenance. Full-grown trees and foliage can hide the
inlets and outlets and make it impossible to see the bottom of the basin. A plan and schedule for
regular maintenance by the City and/or HOAs should be in place and followed to ensure proper
performance of drainage facilities.
Regular maintenance of the facilities will not be enough, however. During the survey, many of
the hillsides were almost barren with some freshly scarified. Much of the blockages in the
facilities are caused by runoff dirt and sediment. The dirt and sediment will quickly return if the
hillsides do not have enough vegetation to hold the dirt. The City should allow foliage to grow on
the hillsides to reduce the runoff water and sediment that reaches the storm drains.
Streets with and without curb/dike should be inventoried to determine which streets would
benefit from channelizing water along the street instead of the shoulder. Dirt shoulders easily
erode and can cause damage to the pavement of the streets. Eroding dirt shoulders also
contribute to sediment runoff. Channelizing the storm water along the streets can more
efficiently direct storm runoffs into storm drain facilities.
Frequent flooding areas on the street or in private property should be more thoroughly
researched on a case-by-case basis to determine cost-effective means of providing relief.
Implementation of the above recommendations will provide the City of Lake Elsinore with a
properly functioning storm drain system.
4-1
MDP-City Wide Drainage Issues
Flooding Ex. Storm DrainNo.Location Primary Issue Remarks Mitigation Measure PhotoSTPP Debris SD CB Cond.
Possible costco fixing with sd. Intersection and dirt shoulders
are very flat.1
2
3rd St / Dexter Ave Y Street flooding flooding entire intersection. nearby development. shoulder grading Y
YPonding on street from street and hill runoff. CB on other side of street. Need to Add berm or C&G to direct water to a new CB that links intoLine St / Lakeshore
Pepper / Dawes
Y
Y
Y
Y
Y
Y
Y
N
Y
Y
N
Y
Standing water
Standing water
Standing water
catch and redirect. Long term ponding at intersection existing CB and SD across the street
LP T-junction, standing water on street, long term ponding. T-intersection taking
runoffs btwn Ave 3 to Ave 6. Pond till spill to Lakeshore3
4
Need major storm drain facility Y
Y
Y
LP T-junction, standing water on street, long term ponding. 6" or 8" SD outlet
not found, not in working conditionHigh St / Parkway Need major storm drain facility
Need major storm drain facilityHillside runoffs sheet cross street flooding property. Runoffs erode road, cross
yard drain to Lakeshore5
6
Country Club / Mill St
Mill St / Ave 1
Y Y Y N N
N
Hillside runoff, Street flooding
Hillside runoff, Street flooding May need SD facility. Excessive dirt may require high
maintenance
May need SD facility. Excessive dirt may require high
maintenance
Hillside runoffs flooding St & PP with silt and debris Y
Y
Y
Y
Y
Y
Y
Y
N
N7
8
9
Mill St / Ave 2 Hillside runoff, Street flooding
Other
Hillside runoffs flooding St & PP with silt and debris
homeowner built rip rap and grading. None to little flooding
No C&G
Strickland Ave / Foster St
E/S Spring / N/O Sumner Low area near street. Add berm or C&G and CB to join ex SD
nearby on Sumner
Add berm, C&G, or concrete dike to collect water and divert to
new SD
Street flooding Y
Y
Y
Y
Y
N
N
N
N
N
N
10
11
Lakeshore / Elm to Country club
Marian / Lakeshore to End
Street flooding Street very flat, unsafe driving cond.
Runoff from Lakeshore eroding edge of pavement and affecting two homes on Berm or C&G to direct water away from edges of street. CBYRoad and PP Damage Marian and SD to collect water before it reaches homes
Lake Park St / Flooding houses on
Herbert St
Possible high point(s) on Lake Park street stops water from
flowing to lake. Grading may allow water to continue12
13
14
N
Y
Y
Y
Y
Y
N N
Y
N
PP Damage Runoff from Lakeshore goes down Lake Park Street and flows into 3 backyards
Street flooding at school site. 18" outlet to bubbler CB, debris at inlet of 18"
RCP, pond over sidewalk, unsafe
Mass silt & debris drain to inlet. 30" SD on Mill, 1/3 inlet silt up. Hillside and Ave
7 erosion
Y
Y
W/O 1331 Mill St - Drain
E/O 1341 Mill St / Ave 7
Y
Y
18"
30"
Street flooding
Hillside runoff
Extend and conn. Exist 18" to SD Main on Mill
Need desilting facility & imp on Ave 7
Ave 6 upstream runoffs drain downhill near Cole, erode natural channel outlet
at Mill. Causes erosion and downstream flooding15
16
17
Ave 6 at Cole Ave Y
Y
Y
N
N
N
N
N
N
Hillside runoff
Hillside runoff
Hillside runoff
Add C&G on Ave 6, use street convey the runoffs
Need x-gutter and C&G on south of Acacia
Y
Y
Y
Acacia / Country club
Chestnut / S/O Prospect
Y
Y
Runoff from hillside flood house. Skewed T intersection
Runoff from EVMWD street. crosses street, heavy silt and flooding goes to
Prospect and Main. May need to catch or redirect at source and at MainY Need to catch or redirect runoffs at source and at Main
18
19
1209 Sumner Y
Y
Standing water
Standing water
HIGH PRIORITY. Deep ponding. Cross gutter or undersidewalk drain
CB and inlet located poorly. Silt on street
Need to install cross gutter or undersidewalk drain
New catch basin at low pointsDutton St / Mid block area
20 339 Chestnut Y Y Y Street flooding
Other
Street is steep and has no drainage facilities. Water runs into PP and ponds New CB and SD to catch water before it leaves Franklin street
Water running down street into single CB. SD only from end of Pottery to FC
channel
Runoff and ponding and flooding. No development in near future. Vegetation to
take care of silt.
More CBs and SD on Pottery street to lessen amount of water
that reaches last CB.21a
21b
Pottery - Main St / Rancho
Pottery - Main St / Rancho
Y
YYY
Y
Hillside runoff
21c
22
Pottery - Main St / Rancho
N/S Flint - Lookout / Main St
Standing water
Hillside runoff
Water running down sides of street. 1 CB at end of street. paving soon
Runoff into PP lowspot, ponding
Add C&G to keep water moving on Pottery to CB.
Add berm or C&G to keep water from PP
Y
Y
Flooding Ex. Storm DrainNo.
1
Location Notes Remarks Mitigation Measure PhotoSTPP Debris SD CB Cond.
Both sides flooding. Low spot in street. Channel dump onto street. Nearby flood
control facilityStreet flooding Install catch basins at low point and add storm drain Y
Y
18740 Collier-Both sides of the road
E/S Collier / N/O Crane - by bus stop
Y
Perform maintenance to clear out channel and pipes. It may
be possible that former channel is completely filled in with
dirt.
25 Y
Y
Y
Y
Standing water Water from channel ponds on driveway/street. Trees and dirt fill in channel
26
27
565 Chaney - area in front
Trelevn / Chaney
Standing water
Hillside runoff
Street and land runoff onto street. Can continue existing berm
Goes through PP and ponds behind berm
Extend existing berm Y
Y
Road is flat. Runoff from hills can be caontrolled and captured
with CB and SD.28
29
30
Gedge - Strickland / Gutakes Y
Y
Y
Street flooding
Hillside runoff
Standing water
Runoff from Chaney Y
Y
Y
Chaney - W/S Strickland / Hill St Y Runoff down Chaney street from unimproved areas. Ponding and dirt debris
High ponding. May need CB. CG same height as crown. Possible existing SD
SD and CB on Chaney down to RCFC channel to north
May need maintain existing SD and add catch basinsLakeshore / Lowell in turn pocket
31
32
33
Hillside runoff
Street flooding
Street flooding
No berm. Water runs into dirt and silt builds up on street.
Ponding in street with dirt
Add berm, cross gutter. May need CB.
Use berm and cross gutter.
Y
Y
Y
W/S Davis / N/O Lakeshore
Lakeshore - Davis / Matich Y
Y Runoff from hills with dirt. Use berm and inlets. Damaged existing drain pipe Repair existng storm drain and add berm and inletsBushman / Lakeshore
May need major storm drain facility or series of small drains
on north side.
Determine if another CB needed on other side of Cowell or on
Ryan Ave to reduce volume of water
34
35
36
37
38
39
40
Y
Y
Street flooding
Hillside runoff
Runoff from hills. Lakeshore Dr can flood due to lake of SD and flatnessLakeshore - Bushman / Illinois
Cowell - Lakeshore / Lakeview
Manning - Ryan / Lakeshore
Runoff from hills and steep street towards lake. Existing CB on one side at
Lakeshore. Dirt runoff.
Runoff from hillside and street street bringing dirt and debris. Water cuts across
street and creates dirt ravine on west side.
Runoff from hills and steep street. Runs near/on PP and then down Illinois.
Water ponds at Illinois and Lakeshore.
Y Y
Hillside runoff Add berm or C&G and CB at bottom of street. Cross gutter
Continue berm around to Lakeshore. Remove low spot from
street corners.Y
N
Y
N
Y
Y
Y
Hillside runoff, ponding
Hillside runoff
Illinois - Lakeshore / Lakeview
Heald / Adams Water from street flowing into PP. Culvert under street. CB not at low point
Water flowing down street and into PP and ponding.
Need to change street grade or add CB at low point
Add berm or C&G to keep water from homes. Add CB and link
to existing CB and SD down the street.Y Y Standing water
Hillside runoff
Heald - W/O Chaney to 1st house
Water runs into open space and into multiple PP. Overside drain on Bailey.
Remove and bring water to DrydenY
Y
May need major storm drain facility12792 Lash - runoff from hillside
16801 Holeborrow
16809 Bell
41
42
43
N
N
Y
Hillside runoff
Hillside runoff
Street flooding
Runoff hill into PP May need major storm drain facility
May need major storm drain facility
May need major storm drain facility
Runoff down hill into PP
Y Flooding street, land, PP, about two feet. Deep flooding for weeksPope circle area
Runoff down street into low basin areas. Possible overside drain and berm into
low area to slow down water.44
45
46
N
N
Hillside runoff
Hillside runoff
May need major storm drain facility
May need major storm drain facility
May need major storm drain facility
LaShell - Pinnell / Bromley
Bromley north to LaShell
Robert / Shrier
Silt and water run down dirt road
Related to uphill runoff on LaShell
Overflow from basins floods road about 1 foot deep. Whole street flooded.
Floods PP.47 Shrier / Gunnerson Y Y Street flooding
Standing water
May need major storm drain facility Y
48
49
McBride / Gunnerson
Herbert St area
Y
Y
Y
Y
Runoff from streets and hills ponding on street. Crosses street to PP
Same issues as Gunnerson points
May need major storm drain facility
May need major storm drain facility
Y
X
Flooding Ex. Storm DrainNo.Location Notes Remarks Mitigation Measure PhotoSTPP Debris SD CB Cond.
Runoff from hill down street and into PP. Needs infrastructure improvements
before much can be done50
51
Bennett St area N Hillside runoff
Hillside runoff
Y
YIngalls Cir - spill way along road edge Y Slight ponding on street. Roadway damage Overside drain needs replacement with rip rap.
Ponding on street. Inlet on street may be clogged. Outlet clogged. May need
clearing and rip rap. Maybe size upgrade52
53
54
McPherson / Pierce
29235 Gunder
Y
N
N
Hillside runoff
Hillside runoff
Hillside runoff
May need unclogg existing inlet and outlet
Install CB and drain to Valley. Repair dike YY
Y
Water runs down hill, across street, into PP.
Berm or C&G to direct water downhill towards SD on
LakeshoreLash / Dryden Water running down hill and across street into PP
Berm or C&G to direct water downhill towards SD on
Lakeshore55
56
57
Dryden between Lash / Cimaron St N
Y
Y
Y
Y
Hillside runoff
Street flooding
Water running down hill and across street into PP
Channel running into streets. Flooding PP. Flooding street. Street is low point.
Cross gutter and channel improvements29700 Hursh May need to add cross gutter and improve channel
31625 Machado near guard rail Low point and flat street. Clean shoulder to allow for flow. Street taper cause
ponding. Maintenance issueStanding water Y
Y
RCFCD Line C in Le Gaye, Machado and Joy, may need to add
catch basins and inletsMachado / LeGaye
32137 Machado
58
59
Y
Y
Y
Y
ponding
Y
Y
Standing water Same issue as other Machado. Ponding in low spot at street taper Exist. SD 500' west, widening st 350' or add SD & CB
Low pt. at Street, no CB, Need to add SD and CBHillside runoffs flooding PP and ST. Erosion from hillside and road runoff. Can
use SD or curb60a
60b
60c
Franklin-Easthill to Ave. 6
Franklin-Easthill to Ave. 6
Franklin-Easthill to Ave. 6
Y
Y
Y
Hillside runoffs
Hillside runoffs
Hillside runoffs
Y
Y
Hillside runoffs flooding PP and ST. Erosion from hillside and road runoff.Low pt. at Street, no CB, Need to add SD and CB
Low pt. at Street, no CB, Need to add SD and CBHillside runoffs flooding PP and ST. Erosion from hillside and road runoff.
Development soon. Offramp and businesses.
Property flooded by culvert
discharge
2-24" Culvert, Rip-Rap at outlet, Storm runoff spreading and flooding the
property61Corydon at Melinda Lane Y Y Y 2-24"N G Channelize downstream from the culvert Y
After an approved project PM 36551 constructed,
ponding will be resolved. Pavement should be
repaired
Ponding at knuckle leads to heavy debris and pavement damage.
Pavement shows aligator cracking and failure in area.62 3rd St / Pasadena Y Y Ponding at Knuckle
Drainage ditch and culvert discharges runoffs to
63 Olive / Mission Trail Y Y Drainage ditch and inlet at Wildomar side need to be maintained private property. Both cities to look into cleaning
responsibilities
Natural watercourse from hill site runs through
property. Need to grade channel to Bushman, add
berm to protect property. Rita email 11/24/15
Maybe grade a berm to prevent flooding the site
per Rita's email 12/16/15
Hillsite runoffs and street
above64 17770 Ryan near Bushman
Stoneman St/ Palomar St
Y
Y
N N
Y
Property flooded by the runoffs from hillsite and street above
Source from RCFC Stoneman Channel
Y
Y65Y
Y
RV Park Site floodingPepper Tree RV Trailer Park
Corydon Flooding between Mission
Trail and Melinda Lane
Heavey rain in 1-2016 caused Due to lack of upstream facilities and existing SEDCO Line E was
servere flooding not fully utilized
See Memo and interim improvement options and
cost estimate66Y
Memorandum
To:Jason Simpson, Financial Manager, City of Lake Elsinore
From: Lin McCaffrey, P.E. Albert A. Webb Associates
Date: January 25, 2016
Re:Corydon Road Flooding Issues
Corydon Flooding Issues and Interim Solutions
During the rain event first week of January, 2016, a section of Corydon Street between
Mission Trail and Melinda Lane adjacent to the City of Lake Elsinore easterly boundary
experienced a heavy flooding. Webb has reviewed the area topographic map, existing
drainage facilities in conjunction with Prelim Wildomar MDP hydrology information, and
conducted a preliminary drainage studies and design options. Below are our findings
and recommended storm drain improvements:
Findings:
1. There are approximate 1700 acres watershed (Wildomar Line E and Line G) from
Wildomar drains cross Corydon Street, discharges into the Lake.
2. The watershed is partially developed with mostly residential, some commercial
land use and 30% to 40% of the vacant land.
3. Wildomar MDP Q100 for Line E is 1,318 CFS, for Line G is 1,661 CFS (fully
developed condition), total Q100 is approximate 3,000 CFS.
4. Except Caltrans Storm Drain Culverts on I-15, SEDCO Basin and Line F at east
of I-15, the only existing drainage facility is SEDCO Line E, a 72” RCP, a 42”
RCP on Mission Trail and daylight channel with a design capacity of 450 CFS.
5. The existing Line E collecting system has 4 catch basins at east side intersection
of Mission Trail and Lemon Street with estimated capacity of 100 CFS. The
existing Line E is most likely under-utilized for the currently conditions.
6. Due to lack of upstream collecting system, increase capacity of Line E or
construct portion of Line G will not effectively alleviate Corydon flooding.
Recommendations:
1. Fully utilize the existing Line E capacity by adding additional catch basins and
drainage inlet on Corydon.
2. Construct a storm drain system on Corydon with catch basins and inlets to
reduce the flooding. Two interim design options are provided pending on the
funding and preferred storm drain outlet location and alignments. See Exhibits
Option 1 and Option 2. The estimated cost for the Option 1 and Option 2 are
approximately $794,000 and $973,000 respectively.
OPTION 1
Location
Prop. SD
Dia Length (ft)
30" 149Corydon St
Corydon St.
Corydon St.
Corydon St.
Cereal St
Prop. SD
Prop. SD
Prop. SD
Prop. SD
36" 483
30" 163
30" 217
48" 909
"Laterals" from Inlets and CB's 382
OPTION 2
Location Dia Length (ft)
48" 151
36" 386
42" 480
48" 612
30" 149
30" 483
Prop. SD
Prop. SD
Prop. SD
Prop. SD
Prop. SD
Prop. SD
Corydon St.
Corydon St.
Corydon St.
Easement to Airport
Cordyon St
Corydon St.
"Laterals" from Inlets and CB's 733
Exist. CB
Exist. Concrete
Channel
Exist. 42" RCP
SEDCO Line "E"LEGEND
City Boundary
Proposed Facilities
Inlet
Catch BasinExist.
72" RCP Existing RCFC&WCD Facilities
I
0 250 500
Feet
1 inch = 250 feet
Corydon Road
Drainage Improvement
OPTION 1
City of Lake Elsinore
Sources: RCFC&WCD, 2014 & 2015;
Eagle Aerial, 2012.
Exist. CB
Exist. Concrete
Channel
Exist. 42" RCP
SEDCO Line "E"
LEGEND
City Boundary
Proposed Facilities
InletExist.
72" RCP Catch Basin
Existing RCFC&WCD Facilities
I
0 250 500
Feet
1 inch = 250 feet
Corydon Road
Drainage Improvement
OPTION 2
City of Lake Elsinore
Sources: RCFC&WCD, 2014 & 2015;
Eagle Aerial, 2012.
APPENDIX B – Exhibits
7-73
LEGEND
Map Grids
B1 East Lake
Lake
Temescal Wash
Alberhill Sub-Zone
City Boundary
Proposed City MDP
Existing City Lines >20"
A1
A2
A3
a ?¦!"B2
C1
B3
C2
Grid Index Map
I
B4 0 3,000 6,000 9,000
Feet
LEGENDProposed City MDP FacilitiesProposed City MDP Basins
Proposed Debris Basin Locations
Existing City Storm Drain Facilities
Existing RCFC Facilities
"
Proposed RCFC LinesExisting CalTrans Drainage Facilities
RCP, APC, CSP, RCB
DitchRCFC BasinsProposed Roads
Proposed MDP Zones
Temescal Wash
LakeEast LakeAlberhill Sub-Zone
Watershed Subareas
10-ft Contours
DB1"DB2"SP/Tract Boundaries
ParcelsCity BoundaryAlberhill Ranch SP
OS
R/W
OS-N OS
I 15
MXU MXUR/WP OS
MFR C-SPR/W
SFR
MXU OSSFR LDRMFR
HDRR-3 Q=70MXUPMXUSFR
LDRMFR
R/W
HDR
OSSCH OSSFR
P
OSSCHPKMFRJHS ES/PAlberhill Villages SP"DB8 LDRCHSFRMXUSFR MDRAlberhill Ridge TTM Alberhill Ranch SPOSHDRR-SFLLOS MDRHDR
OSOS
OS P
OS-N MFR LDR IPKSFR
SFR OS 0 600 1,200 1,800PHR
01 Feet6--005AeinLOSMDR Grid A1Alberhill North
RCDOSRC36"PMFRC-1DB9A"
MXUSFRSFR
OSPWR-M Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; Riverside
HDRMurdock Alberhill Ranch SP Co. GIS, 2016; NAIP Imagery, 2014.MFR MXUSFR OS
C-1SFR
SFR Alberhill RCDOS OSRidge TTMSFRMFRHDRMXUAlberhill Villages SP OS
R/W Alberhill Ranch SPAlberhill Ranch SPCH
SFRAlberhill Villages SP Alberhill Ranch SPR-SF Murdock AlberhillRanch SP
C-H C-SPPKSOSHRR-3PKSPR-MSFR
"DB9 MDROS
Line A08
Alberhill Villages SP
Outlet Center SP
RUNNING DEER RD Murdock AlberhillRanch SP
LinQ=138.8
54"
eT02
MOUNTAIN ST Q=17548"Q=9842"Cape of Good Hope SP .3
"01 TR 36557=1Q36
!.SPRUCE ST !.HARRISON AVE
!.
!.!.DRGERIDNTCEESCR !.
La Laguna Estates SP !.!.!.
LEGEND !.!.!.!.Proposed City MDP Facilities SPINDRIFT CIR !.!.Proposed City MDP Basins
Proposed Debris Basin Locations
Drainage Issue Locations
Existing City Storm Drain Facilities
Existing RCFC Facilities
!."!.!.!.
!.
Proposed RCFC LinesExisting CalTrans Drainage Facilities
RCP, APC, CSP, RCB
Ditch
!.
!.
!.
CAMPHOR WAY Lakeshore Village SPRCFC Basins !.
IRONWOOD STProposed Roads
Proposed MDP Zones
Temescal Wash
Lake
!.I!.!.East Lake 0 600 1,200 1,800Alberhill Sub-Zone
Watershed Subareas
10-ft Contours
!.FeetGrid A2South Alberhill/!.SP/Tract Boundaries
Parcels
West Lake Area !.
Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCity Boundary Co. GIS, 2016; NAIP Imagery, 2014.
The Village atLakeshore
LakelandVillage
LEGENDProposed City MDP FacilitiesExisting City Storm Drain Facilities
Existing RCFC Facilities
Proposed RCFC Lines
RCFC Basins
Proposed MDP ZonesTemescal Wash
Lake IEast Lake 0 600 1,200 1,800Watershed Subareas
10-ft Contours
SP/Tract Boundaries
Parcels
FeetGrid A3West Lake AreaSources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCity Boundary Co. GIS, 2016; NAIP Imagery, 2014.
I LEGENDProposed MDP Zones
Temescal Wash
Lake
0 600 1,200 1,800FeetGrid B1North City Area East LakeWatershed Subareas
10-ft Contours
Parcels
Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.
City Boundary
MOUNTAIN AVE
FIG ST
I LEGENDProposed City MDP Facilities06001,200 1,800 Proposed City MDP Basins
Proposed Debris Basin Locations
Drainage Issue Locations
FeetGrid B2North City Area
"
!.
Existing City Storm Drain Facilities
Existing RCFC Facilities
Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.Proposed RCFC LinesProposed Wildomar MDP FacilitiesExisting CalTrans Drainage Facilities
RCP, APC, CSP, RCB
DitchRCFC BasinsProposed Roads
Proposed MDP Zones
Temescal Wash
CIRUTKOOLO
LakeEast LakeAlberhill Sub-Zone
Watershed Subareas
10-ft Contours
SP/Tract Boundaries
Parcels
DB10"MAURICIO ST
42" RCP
City BoundaryOS Alberhill Ranch SP ¦
TR 25476
"C-SP DB5
TR 25479
TR 30698
Outlet !.Center SP GAFFEY DR RAMSGATE SPTR 11283
TTM 32537 TR 25478
TR 31792
Tuscany Hills SPDB11"
Ramsgate SP(TTM 35422)-16LeinL
TR 31593!.
!.
!.
DB6"
1.13 1Q=42 PRC"TR 31593 "South Shore I"(with proposed lots)
Ramsgate SP
!.
LA STRADA!.
!.
Spyglass Ranch SP (TR 35337)Canyon Creek SP(with proposed lots)LOELNTSADEL!.!.TR 36567 (South Shore II)(with proposed lots)
-18-2e LLin
!.!.!.
POTTERYST
Line!.L-6!.!.!.
!.'
!.POTTERYST
!.!"!.
!.!.!.'
Q=8536"RCP !.!.!.!.!.
!.!.LEGEND PE!.CKSTProposed City MDP Facilities
Proposed City MDP Basins
Proposed Debris Basin Locations
Proposed WQ Treatment Facilities
Drainage Issue Locations
DR'!.IDGRELEDDSALIMITEDAVE!."Canyon Creek SP!.'
!.!.
Existing City Storm Drain Facilities
Existing RCFC Facilities
!.MILL ST !. !.!.
!.!.Proposed RCFC Lines PARK WAY!.!.Proposed Wildomar MDP Facilities GCExisting CalTrans Drainage Facilities
RCP, APC, CSP, RCB
Ditch
!.!.OS
MDRLMR !.!.Q=181 Elsinore City Center48" R !.MDR CPMDRRMHDRMDRRCFC Basins HDR HDR !.
HDRHDREast Lake SPProposed Roads
Proposed MDP Zones
Temescal Wash
Lake
F'MDROS HDR
RM
!.RM'MDR
RM
RM MDR RM IOS'OSOS
MDRMDR
RM
OS RM
OS RM 0 600 1,200 1,800OSEast Lake TC FeetWatershed Subareas
10-ft Contours
Grid B3North Lake Area
LMR LMR Diamond SPEast Lake SP GC
TCSP/Tract Boundaries
Parcels
Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.
OSLMR
OSOS RLMR
OSLMR Diamond SP
MDR R CMTC
LMR
LMRLMR
LMR OS
LMR LMRGCLMROSLMROS
LMR LMRLMR
OS
East Lake SP(Summerly)LMR
LMR LMR HDROS MDRLMROS
OS East Lake SP MDR
LMR MDR LMR
LMR HDR
HDR OS
LMRPI MDR
HDR GCLMRLMR
LMR
MDRLMR HDRMDR
HDRLMR LI
LI
AUA
OS
LEGEND LI
Proposed MDP Zones
Temescal Wash
Proposed City MDP FacilitiesProposed City MDP Basins
Existing City Storm Drain Facilities
Existing RCFC Facilities
Proposed RCFC Lines
Proposed Wildomar MDP Facilities
RCFC Basins
LakeEast Lake AUAEast Lake SP Land Use
FloodwayAirport Use Area
Limited Industrial
Tourist Commercial
General Commercial
Residential Mixed Use
Low-Medium Residential
Medium Density Residential
High Density Residential
Recreation
Proposed RoadsWatershed Subareas
10-ft Contours
LMR ISP/Tract Boundaries
Parcels
0 600 1,200 1,800FeetMDRGrid B4City Boundary East Lake AreaSources: City of Lake Elsinore, 2014-2016RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.
Open Space
1600
LEGENDProposed City MDP FacilitiesExisting City Storm Drain Facilities
Proposed Lake MDP Zone
Watershed Subareas
10-ft Contours
1600
9016
SP/Tract Boundaries
Parcels
1660
1440 City Boundary
1680 1620
1770
1570
15301480
1480
1530 1480 1380
1380
1530
1470
Tuscany Hills SP 1470
1390
1460
1380
14001520 I06001,200 1,8001380FeetGrid C1NE City AreaSources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.1380
1380
1380
1390 13901390
1390
13901400 1440
1410 143014401420
1460
1480
1510 14801490 1450
1420
Tuscany Hills SP
1350
1510
1450
1730
1770
BIG TEE DR1680
DESERTROSEWAY
1570
1340
1540
RDSMOSSCanyon Creek SP
LOB
1490
1560
Q=769 cfs 1490
1740
1530Canyon Hills SP 1790
GLOXINIA WAY1018
CEDAR CREEK LN HILLSIDE DR
1640
17901560
1790Q=463 cfs Q=114 cfs Q=226 cfs Q=657 cfsQ=483 cfs
16401550
1610
2190
6016 1720
1820
LEGEND 1690Existing City Storm Drain Facilities
Existing City Basins
Proposed Lake MDP Zone
Watershed Subareas
Flowlines
IQ=141 cfsQ=290 cfs
0 600 1,200 1,800Feet10-ft Contours Grid C2SE City Area
SP/Tract Boundaries
Parcels 1750 Sources: City of Lake Elsinore, 2014 &City Boundary 2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2016; NAIP Imagery, 2014.2010
1760
LEGENDCalTrans Culverts
APCCSPRCPOther CalTrans Structures
RCBDitchCity Storm Drains (>36")
RCFC Facilities
RCFC BasinsCity Detention Basin
10-ft City Contours
City Boundary
0 1,000 2,000 3,000Feet
Not to Scale
CalTrans CulvertsCity of Lake Elsinore
Sources: CalTrans, 2015; City ofLake Elsinore, 2014-16; RCFC&WCD,2014; USDA NAIP, 2014.
TypeA Ditch
LEGENDGDrainage Issues¦City-owned Storm DrainFacilities GT 20"RCFC&WCD Facilitiesin City LimitsSTARINA ST City Boundary
G
GGGGGG
GG GGGG G GGGGGGGG
GGGGG G
G GGGGGGGGG IGPO
LD
TTERYSTGGG GGGHEA 0 2,000 4,000 6,000G!"G AVE GG G FeetG G GGGGGGGG GGMILL ST GGGGGGGGGGGG GGG Drainage Issue AreasCity of Lake Elsinore
Sources: City of Lake Elsinore, 2014-16;RCFC&WCD, 2014;Riverside Co. GIS, 2015.
LEGENDProposed MDP Zones
Temescal Wash
LakeEast LakeCity Boundary
¦?
a!"
I
0 1 2 3
Miles
Existing MDP MapCity of Lake Elsinore
Source: City of Lake Elsinore
¦
!"
LEGENDCity BoundaryProposed MDP ZonesTemescal Wash I
4,000
LakeEast LakeRCFC MDP Areas 0 2,000 6,000 8,000FeetWest Elsinore MDPLakeland Village MDPSedco MDPSoil Hydro GroupA
B
C
D
N
Soil Hydro Groups andProposed MDP ZonesSources: USDA NRCS SSURGO, 2008;Riverside Co. GIS, 2015.
¦
!"
LEGENDCity BoundaryProposed MDP Zones
Temescal Wash ILakeEast Lake 0 2,000 4,000 6,000 8,000RCFC MDP Areas
West Elsinore MDP
Lakeland Village MDP
Sedco MDP
Feet
Consolidated Land Use Categories
Very Low Density Residential
Low Density Residential
Medium Density Residential
High Density Residential
Commercial
Consolidated GeneralPlan Land UseDesignations for MDPParksSources: City of Lake Elsinore, 2014; RiversideCo. GIS, 2016; City of Menifee, 2014; City ofWildomar, 2015; City of Canyon Lake, 2003.
Open Space
LEGENDProposed MDP ZonesEast LakeLakeTemescal WashAlberhill Sub-Zone, Tem. WashCapital Improvement FacilitiesProposed City MDP FacilitiesProposed City MDP Basins
RCFC MDP AreasWest Elsinore MDPLakeland Village MDPSedco MDP
RCFC&WCD FacilitiesRCFC Proposed LinesCity Detention BasinRCFC Basins
AlberhillSub-Zone
City Boundary¦
TemescalWash ZoneWest Elsionre MDP Lake Zone
!"IEast LakeZone
0 2,000 4,000 6,0001 inch = 2,166 feetFeetProposed MDP DistrictsSedocMDP
City of Lake ElsinoreLakelandVillage MDP Sources: City of Lake Elsinore, 2014 &2015; RCFC&WCD, 2014 & 2015; RiversideCo. GIS, 2015; NAIP Imagery, 2014.
LEGEND"Proposed Debris BasinsCity BoundaryCity Detention BasinRCFC Basins
Watersheds/SubwatershedsA1A2""A4-2
A5-1
A8
DB1 DB2
A9A9A
A10
A11
"DB8 ""DB9A DB10!"a ?¦""IDB9DB5
0 2,000 4,000Feet
6,000 8,000"DB11"Proposed DebrisBasinsDB6
City of Lake Elsinore
Sources: City of Lake Elsinore, 2014and 2015; USDA NAIP 2014
3142 31433246
31443248
31453249
3146 3158 3161
3263
3164
3267
3166
0
3173
3277
3174
3278
3175
3279
31763245
3348
3268
3366
3276
3378
3349 3350
3448
3351
3449
3547
3645
3745
3844
3946
4048
4148
3372 3370
3475
3377
3467
3450 3457
3555
3458
3556
3654
3756
3856
3959
4060
3477
3574
3671
3773
3473 3470
3565
3545 3546 3548 3549
3647
3550
3648
3748
3572
3670
3772
3875
3569
3667
3564 3570
3665
3760
3646
3746
3649
3749
3849
3951
3650
3750
3850
3952
4054
4154
4251
3653
3751
3854
3953
4055
4155
3651
3752
3855
3954
4056
4156
3652
3753
3853
3957
4057
4157
3658
3759
3859
3964
4067
4166
3672
3767
3685
3775
3673 3656
3755
3659
3757
3744 3774
3869
3976
03846
3948
4050
3862
3966
4070
4169
4266
3864
3970
·|}þ74
3851
3955
0
3949 3950
4152
3977 3971
4079
4180
4276
3974
4076 4078
4176
4272
4071
4171
4268
4153
4250
4178
4273
4174
4270
§¨¦215
4367
4459
4548
4365
4456
4549
·|}þ74 §¨¦15 4550
4648
4745
4838
4553
4649
4747
4847
4556
4651
4749
4848
4945
5044
4559
4656
4646
4743
4846
4937
4647LEGEND4759
4843
4740 4742City Boundary 4844
4940
4845
4939
4849
4946
5045
Proposed MDP ZonesRCFC MDP Areas
4951
5049
5149
MSHCP Criteria Cells 5038 5033
5140
5036 5046
5145
5248
Burrowing Owl Survey AreaNarrow Endemic Plants SurveyArea - Codes 1 and 2
5137 5131 5259SKR Fee Area Boundary
5240
5342
5247 5245 5252
5354 5355
5253
5356
5254
5357
5255
5358
52565350535153525366Source: Riverside Co. GIS, 2016.USDA NAIP, 2014.
Figure 5-1 - MDP Zones with MSHCP Criteria Cells and Survey AreasI Lake Elsinore Master Drainage Plan0123Miles
·|}þ74
§¨¦215
·|}þ74 §¨¦15
LEGENDCity BoundaryProposed MDP ZonesRCFC MDP Areas
Paleontological SensitivityHigh ASource: Riverside Co. GIS, 2016.USDA NAIP, 2014.
Figure 5-2 - MDP Zones with Paleontological SensitivityI Lake Elsinore Master Drainage Plan0123Miles
LEGENDCity Boundary"Blue Line" StreamsNWI WetlandsRCFC MDP AreasWest Elsinore MDPLakeland Village MDPSedco MDP
·|}þ74 East LakeLakeTemescal WashAlberhill Sub-Zone§¨¦215
·|}þ74 §¨¦15
Sources: NHD, 2015; USFWS, 2015;Riverside Co. GIS, 2016.
Figure 5-3 - MDP Zones with Wetlands and "Blue Line" StreamsI Lake Elsinore Master Drainage Plan0123Miles