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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 -