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Home My WebLink AboutDrainage Report December 2008llB~ 111 DRAINAGE REPORT FO R THE QUARTERS AT LUTHER STREET PREPARED FOR: TUCKER MACH DEVELOPMENT, L.L.C. 41978 Hempstead Hwy Waller, Texas 77484 DECEMEBER 3, 2008 MBESI# 1082-0003 SUBMIITED BY: McCLURE & BROWNE E NGINEERING/SURVEYING. INC. LOOS Woodcreek Drive, Suite 103 •College Station, Texas 77845 (979) 693-3R3R -fox: (979) 693-2554 THE QUARTER AT LUTHER STREET Stormwater Management Technical Design Summary Report MBESI #1082-0003 PART 1 -Executive Summary Report Section 1 -Contact Infonnation: Project Designer: Project Developer: Submittal Date: McClure and Browne Engineering and Surveying, Inc. 1008 Woodcreek Drive, Suite 103 College Station, TX 77845 979-693-3838 Tucker Mach Development, L.L.C. 41978 Hempstead Hwy Waller, TX 77484 (713) 213-4647 December 3, 2008 Section 2 -General Infonnation: This development is a multi-family residential development to be constructed in College Station. The development consists of one lot and one block. The total area of the development is approximately 1.583 acres. Section 3 -Project Location: The Quarters of Luther Street will be located in College Station approximately 0.46 miles north of F.M. 2818 along Luther Street West. The entire project is located within the city limits of College Station. The entire site is located within the Whites Creek drainage basin. No portion of the site is shown to be within the 100-year floodplain; therefore, it is not currently regulated under the National Flood Insurance Program. (FEMA Firm Map# 48041C0182 C, effective July 2, 1992.) Based on Figure B-19, Appendix B of the Unified Stormwater Design Guidelines, the site is located in the Whites Creek drainage basin defined in the table. After evaluating the site, it was determine that detention will be necessary. Section 4 -Hydrologic Characteristics: This project site is mostly pasture grassland with medium brush areas and spots of small trees. The terrain is relatively flat slope in a south-westerly direction. Storm water drains into an undeveloped track on the south-west side of the site and eventually drains to Whites Creek. Stormwater Management Technical Design Summary Report Tucker Mach Development, L.L.C. Section 5 -Stormwater Management: The proposed site is mostly surrounded by developed property in the north, east and south directions. The surrounding developed areas consist of concrete parking and graded grass areas. These areas are elevated higher than the project site; therefore, the proposed site grading is designed to capture site runoff and the existing runoff draining into the site from the surrounding areas. Refer to Exhibit B-1, pre-development condition drainage map. Three detention facilities will be provided for this project. Due to the nature of the existing terrain and storm water drainage conditions, the site is graded such that three shallow detention ponds are proposed. The site is divided into three drainage areas as shown in post-development condition drainage map, Exhibit B-2. Detention ponds #1 and #3 will capture most of the site's runoff. The stormwater from Pond #1 will directly discharge at the Point oflnterest shown on Exhibit B-2. Stormwater from Pond #3 will discharge into a 2'wide concrete flume and conveyed to the Point of Interest. The drainage area for Pond #2 is the smallest and stormwater is conveyed to the pond via a 2' wide concrete flume. Stormwater from Pond #2 will be discharged into the gutter on Luther Street. Outfall structures for Ponds #1 and #3 consist of a concrete structure with a rectangular opening and weir. The outfall structure for Pond #2 is a trapezoidal shaped concrete channel and will connect to a rectangular channel that will discharge into the Luther Street gutter. The design top of berm elevations for Ponds #1, #2 and #3 are 327.20', 328.00' and 328.25', respectively. Table 1, summarizes that the pre and post-development flows for all design storms at the Point of Interest #1. Compared to the pre-development flows at the Point of Interest #1 for post-developed flows will reduce the runoff from the site. Table 1: Pre-Development and Post-Development Flows at Point of Interest Storm Pre-Development Post-Development Water Surface Event (cfs) (cfs) Pond #1 Pond #3 (yr) (ft) (ft) 2 3.30 3.29 326.86 327.95 5 5.62 5.19 327.00 328.05 10 7.32 6.51 327.06 328.10 25 8.76 7.58 327.10 328.14 50 10.79 9.05 327.15 328.19 100 12.53 10.28 327.19 328.22 Stormwater Management Technical Design Summary Report Tucker Mach Development, L.L.C. Table 2, summarizes that the pre and post-development flows for all design storms at the Point of Interest #2. Compared to the pre-development flows at the Point of Interest #2 for post-developed flows will increase slightly in the gutter along Luther Street. During the more frequents smaller storms (i.e. 25-year and smaller), the increase inflow will be less than 1 cfs. This small amount is considered insignificant and will have little to not impact on the street. The 50 and 100-year storm events the runoff into the gutter is 1.15 and 1.31 cfs, respectively. Based on the street cross section, slope (i.e. 1.13%) and a 12' spread, the capacity of the gutter is 12.5 cfs. Even during the 50 and 100-year storm events, the runoff entering the gutter from this development will not adversely impact the capacity of the street. Table 2: Pre-Development and Post-Development Flows at Luther Street Storm Pre-Development Post-Development Water Surface Event (cfs) (cfs) Pond #2 (yr) (ft) 2 0 0.43 327.64 5 0 0.66 327.75 10 0 0.82 327.81 25 0 0.96 327.86 50 0 1.15 327.92 100 0 1.31 327.97 Section 6 -Coordination and Permitting: No coordination or permitting is required for this development. Section 7 -Reference: Exhibit A Exhibit B-1 Exhibit B-2 Exhibit C Technical Design Summary Report Existing Conditions Drainage Map Post-Developed Conditions Drainage Map HydroCAD Report Stormwater Management Technical Design Summary Report Tucker Mach Development, L.L.C.