HomeMy WebLinkAboutTR 35337 HYDROLOGY REPORT-014 Spyglass Ranch Tract 35337
Hydrology Study
Results and Summary
This study divides and models the site into sixteen existing condition
drainage areas and thirteen developed condition drainage areas. The
existing areas are designated as Areas 1 through 16, and the developed
areas are designated as Areas "A" through "M," as depicted in both the
Stage 1 and Ultimate Developed Condition Hydrology Maps. Note that for
ease of reference, the drainage area designations shown on the all the
hydrology maps and exhibits represent the same drainage areas (for
example, existing Area 9 as modeled in the rational method analysis is the
same existing Area 9 modeled in the existing unit hydrograph analysis).
As already discussed, the rational method analysis was performed on
both the Stage 1 and Ultimate condition scenarios. The node model data
flow sheets for each analysis, including the existing condition, are provided
for reference in the Exhibits section of this report. The flow rates resulting
from the rational method analysis are used in determining the volume
street flow, catch basin sizing and locations, and the storm drain pipe
necessary to achieve the design criteria. Street capacity and catch basin
design summary tables are provided in the Exhibits section of this report.
Table 2 is provided to summarize the Stage 1 condition results of the
rational method study. The table presents only the peak 100-Year flow
rate values for purposes of comparison where appropriate. Discrepancies
between Developed and Existing conditions indicated in the table, as well as
other hydrological concerns, are discussed in the sections following.
Table 2: Rational Method Summary - Stage 1 Condition
Developed Developed Existing
Condition Area
Equiv. Existing Developed Existing Total Total
(Stage 1) Condition Area Q(100yr) Q(100yr) Area (Ac) Area
(ac)
A 1 172.1 14.6 70.37 4.72
B 2 45.6 138.1 18.81 50.04
C 4 180.8 193.6 65.71 67.37
D 9 73.6 86.1 30.66 29.81
D.18 & D.19 6, 7, 8 12.2 20.9 4.68 6.60
E 12 134.0 199.4 53.18 71.12
F-G 13 55.3 64.1 27.77 21.64
H 14 32.5 39.6 10.00 12.56
I 15 11.1 7.3 2.85 2.04
J 16 34.3 29.2 10.82 9.73
K 3 5.4 36.0 2.15 11.00
L 5 28.3 31.0 12.56 W.55
M 10, 11 14.0 36.2 4.35 10.47
Totals 313.91 307.65
H: \265324\Final\llydrology\Report\324 Report Body.docx - 10 -