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Sanitary SewerCOTTEN SUBDIVISION SEWER CAPACITY CALCULATIONS S: \P roj \0428 - Kenny- Cotten's \xls \sewer- capacity- study.xl s 'Street area (FM2818) not in area calculation because it contributes no sewer flow Exhibit 2 .c c rn L 7 AA C i v� g N T c cn Cv C �� C �, is m " V =a c Cd C aid M L �a � c o C a a .> . 2 : tu V2 w a = W �aC V a► mE V � ._ O ^ W J J .J N © (A W L J in O 0 en W _ > U a � 2 Lfl Us 12 spencer Thompson COC S -Development Services P.O. Box 9960 College Station, TX 77840 August 17, 2004 RE: Cotten's Subdivision Sanitary Sewer Capacity— FM2818 at Dartmouth Dear Spencer: This letter is intended to serve as a sanitary sewer capacity report for the Cotten Subdivision located at FM 2818 and Dartmouth. The subdivision consists of two lots, both with frontage along FM 2818 and the future Dartmouth extension. There is an existing eight inch (8 ") sanitary sewer line which runs along the southern right -of -way of FM 2818 which we intend to utilize for the sanitary sewer service to these two lots. The land area which contributes to this existing sewer line was broken into four sewer areas, as shown on Exhibit 1. Sewer area 3 was broken into an additional sub -area to size the sanitary sewer lines required to serve the first phase of the Cotten Subdivision. Additional growth along Dartmouth associated with the mixed use area to the south will be sewered by the eighteen inch (18 ") sanitary sewer line to the southeast. Based on the 2004 Comprehensive Land Use Plan and flow calculation Method 2 as outlined in the B /CS Unified Water & Sewer Design Guidelines manual, projected cumulative sewer flows generated for the sanitary sewer areas are as follows: The capacity and sizing of the sanitary sewer lines was based on the Manning's equation, with an "n" of 0.013. The slope on the existing sanitary sewer line along FM2818 was assumed to be the minimum TCEQ slope for an eight inch (8 ") diameter pipe (0.334 %). This slope was chosen because this section of sanitary sewer, which was constructed in 1974, was not built as designed and adequate as -built drawings were not available to determine the constructed slope. The slope of the existing eight inch (8 ") sanitary sewer line which runs along Sewer Area 4 was assumed to be 0.47 %, based on survey data and construction drawings. A summary of the diameter required to maintain a velocity of 2 feet per second for ultimate development for each sewer area is shown below. Sewer Area 3b, as shown on Exhibit 1, is a sub - area created to size the sanitary sewer line required to serve the first phase of the Cotten development. Land use for this portion of Sewer Area 3 was assumed to be completely commercial due to the recent rezoning, although the 2004 Comprehensive Land Use Plan shows this area composed of park land, mixed use, and planned development areas. The capacity and sizing of the new sanitary sewer lines was based on the Manning's equation, with an "n" of 0.013. The slope on the new line was based on the slope requirements as shown in the B /CS Unified Water & Sewer Design Guidelines manual. Results of these calculations are shown below. As shown above, the existing and proposed sanitary sewer lines in the area are sufficiently sized to service ultimate sanitary sewer flows for Lot 1 and Lot 2 of the Cotten Subdivision. Please refer to Exhibit 2 for additional capacity and line sizing calculations. If you have any questions or co erns please feel free to contact Q,,.. s So . .... � �4 Si c0ely, i *: VERONICA J.B. MORGAN 7768 . 9 : Q Veronica J.B. Partnerrg E. Managing cc: file Kenny Cotten Attachments: Exhibit 1 —Sewer Areas Exhibit 2— Calculations S:\Proj\ 0428 - Kenny- Cotten's \docs \0428 -ss_ capacity- 040827. doc