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Home My WebLink AboutSewer Sytem ReportSewer System Report for The Barracks II Subdivision College Station, Texas July 2011 Prepared By: Phillips Engineering 4490 Castlegate Drive College Station, Texas 77845 (979)690-3141 TPBE FIRM #13130 II_ICO -7 zG'A LA-.15 GENERAL INFORMATION The Barracks II Subdivision is a 108-acre development in the area generally bounded by Wellborn Road on the east, Holleman Drive South on the west, Cain Road to the north and Rock Prairie Road to the south. It is zoned PDD and is comprised of a mixture of residential and commercial land uses as shown in the Preliminary Plat on Exhibit A. There are 425 residential lots planned for the site and 25.3 acres of commercial property. The area surrounding the site is generally undeveloped, with the exception of three residential developments adjoining the tract on the south. The area between Cain Road and Rock Prairie Road is described as General Suburban in the City's Comprehensive Plan, which implies that it is likely to develop in a similar manner as The Barracks II Subdivision. Sewer service to the area is provided by 18" and 12" lines running along Old Wellborn Road and along the south property line of The Barracks II Subdivision. These lines will be the primary outfall for this development, but they are also intended to serve other adjoining tracts in the same sewer basin. An Excel Spreadsheet Model was used to model the proposed system in The Barracks II Subdivision. This model computes the amount of flow anticipated in each line segment and computes the minimum slope required to carry that flow. If that minimum slope is greater than the minimum allowable slope from the BCS Design Guidelines, the line is deemed to be acceptable. Design Criteria: Primary Sewer Outfall: 18" and 12" sewer lines along Old Wellborn Road Domestic Demand: Avg. Pop Density: 2.67 people per lot Average Flow: 100 gpd/cap or 267 gpd per lot Peaking Factor: 4 Pipe: PVC D3034 SDR 26 Applicable Exhibits: Exhibit A— Overall Sewer System Layout Exhibit B — Sanitary Sewer Analysis Spreadsheet Conclusion: The sewer system shown in Exhibit A has been laid out using the criteria in the Bryan/College Station Design Guidelines. It is analyzed assuming peak flow conditions when the subdivision is fully developed. The spreadsheet in Exhibit B shows all lines depicted in Exhibit A to be capable of carrying of the flows that come to them under these conditions. There are four line segments that need to be noted due to their required slopes. The first two are between manholes MH2O0 & MH300 and MH300 & MH400. These lines have required slopes that are slightly more than the minimum required in the BCS Design Guidelines. Slopes of 0.32% were required on the 12" lines. Immediately downstream of those lines between manholes Ex16 & MH100 and MH100 & MH 200 the lines must be laid at a flatter slope than required in the BCS Design Guidelines. Slopes of 0.20% were required on those two lines. Intuitively, one would assume that a downstream line carrying more water would require a greater slope, but the mathematics used to compute the minimum required slope produces results that vary from this intuitive logic. A slope of 0.20% was used in the design of the two lines segments. While slightly lower than the BCS Design Guidelines, that slope still meets the minimum requirements of TCEQ for a 12" line and it produces mathematically correct results. This analysis will be used as the basis for all subsequent sewer line designs in the subdivision. The system will function as intended as long as the line sizes and slopes are equal to or greater than those shown herein, except as noted in the paragraph above. It should also be noted that any significant additional flow from off -site sources will likely exceed the capacity of several lines, so careful study is advised of any changes to the contributing area. JOHN WHEELER BARGER, TRUSTEE (18.06 west of channel) 1010 15' PUE; 15' UE 1- T I 8 ° SKI PAR[ I AMENTITI _ I i Tip I — e 1.7 ac �--812 ._ 81 1 --_ �- � �- - --� T - -i 8 ° COMMET Al 3.85 ac 000soo 800 , t /Y 700 .60 1110 500 522s s-s 521 ss sb 5iy� t I I i I i T College Station ISD 27.017 ACRE TRACT A— j (23.5 ac outside of ROW) 532 531 5 rJ '. I + ( if -- �54 541 � I v 543 1 550 TURNER TRACT 51 24.99 ac MAYO TRACT (1$.08 a'c north of Kate Ln) I JOHN WHEELER BARGER, TRUSTEE (11.95 east of channel to ex sewer line) MH15 15' PUE i 15' PUE EI I � rti i DETENTION POND DET. COMMERCIAL POND TRACT 2 i I n (3.47 ac to ex sewer li ) i 10 s- s s m ,.., z-,o 4' 0 sL12 s-1z 1 s-m— 1.0q EXI Park (0.35 ac) 7L Park (0.35:ac) ut s Park { (0.38 cc) 1 I Park (0.38 ac) I 1 i _ 201 COMMERCIAL -- 20 � 43 ---- TRACT 3 — --- (8.53 ac to ex sewer line) 410 I Park (1.62 ac) ._._..__ f 4L I 202 1 i iN 7 � --- ____ _ COMMERCIAL TRACT 4 22 J_4] 2 (7.50 ac to ex sewer line) 5 2 Park Park I !I (0.36 ac) (0.35 ac) 203+ I j 1300 j _ 5t-3— 1301 1302 - x 4 400 I € 514 IEX2 EXBK - 5-12 — EXHIBIT A THE BARRACKS II SUBDIVISION Sewer System Layout Exhibit B The Barracks II Sewer Analysis Spreadsheet Line Contributing Flows Flow Calculations Pipe Calculations From To ba m 94 ,bpe o U y .0e o v o W Z e o= e e ; a o. e e U Average Daily Flows (ADF) Infiltration (10%ADF) Peaking Factor Peak Flows Size Material Mannings n Inside Diameter Manning Friction Slope Peak Flows Min. Design Slope Peak Flows Actual Slope for Existing or Designed Systems Pipe Slope Check Peak Flow Depth 267 GPD per Lot 1200 GPD per Acre 1500 GPD per Acre 1050 GPD per Acre MH # MH # Lots Acres Acres Acres GPD GPD GPD CFS CFS CFS in. Inches % % % Inches 543 542 0 0 0 0 - 0,0000 0.0000 4.00 0.000 8 D3034 0,013 7.754 0.000 0.40 0.40 OK 0.78 542 541 12 0 0 0 3,204 3,204 0.0050 0.0005 4.00 0.020 8 D3034 0.013 7.754 0.234 0.40 0.40 OK 1.13 541 540 10 0 0 0 2,670 2,670 0.0041 0.0004 4,00 0.017 8 D3034 0.013 7.754 0.220 0.40 0.40 OK 1.07 550 540 2 0 0 0 534 534 0.0008 0.0ool 4.00 0.003 8 D3034 0.013 7.754 0.030 0.40 0.40 OK 0.84 540 530 4 0 0 0 1,068 534 1,602 0.0025 0.0002 4.00 0,010 8 D3034 0.013 7.754 0.142 0.40 0.40 OK 0.95 522 521 12 0 0 0 3,204 3,204 0.0050 0.0005 4.00 0.020 6 D3034. 0.013 5.793 0.488 0.80 0.80 OK 0.99 521 520 11 0 0 0 2,937 3,204 6,141 0.0095 0.0010 4.00 0.039 6 D3034 0.013 5.793 0.583 0.80 0.80 OK 1.29 520 530 5 0 0 0 1,335 6141 7,476 0.0116 0.0012 4.00 0.047 6 D3034 0.013 5.793 0.599 0.80 0.80 OK 1.41 532 531 12 0 0 0 3,204 3,204 0.0050 0.0005 4.00 0.020 6 D3034 0.013 5,793 0.488 0.80 0.80 OK 0.99 531 530 10 - 0 0 0 2,670 3,204 5,874 0.0091 0.0009 4.00 0.037 6 D3034 0.013 5.793 0.582 0.80 0.80 OK 1.26 530 510 0 0 0 0 14,952 14,952 0.0231 0.0023 4.00 0.095 8 D3034 0.013 7.754 0.326 0.40 0.40 OK 2.08 514 513 3 0 0 0 801 801 0.0012 0.0001 4.00 0.005 6 D3034 0.013 5.793 0.213 0.80 0.80 OK 0.68 513 512 3 0 0 0 801 801 1,602 0.0025 0.0002 4.00 0.010 6 D3034 0.013 5.793 0.425 0.80 0.80 OK 0.78 512 511 13 0 0 0 3,471 1,602 5,073 0.0078 0.0008 4.00 0.032 6 D3034 0.013 5.793 0.548 0.80 0.80 OK 1.18 511 510 28 0 0 0 7,476 5,073 12,549 0.0194 0.0019 4.00 0.080 6 D3034 0.013 5.793 0.676 0.80 0.80 OK 1.76 510 500 22 0 0 0 5,874 27,501 33,375 0.0516 0.0052 4.00 0.212 8 D3034 0.013 7.754 0.365 0.40 0.40 OK 3.03 1200 1100 0 0 3.85 0 17,325 17,325 0.0268 0.0027 4.00 0.110 8 D3034 0.013 7.754 0.350 0.40 0.40 OK 2.22 1110 1100 0 0 0 0 - 0.0000 0.0000 4.00 0.000 8 D3034 0.013 7.754 0.000 0.40 0.40 OK 0.78 1010 1000 10 1 0 0 0 2,670 - 2,670 0.0041 0.0004 4.00 0.017 8 D3034 0.013 7.754 0.220 0.40 0.40 OK 1.07 1100 1000 3 1 0 0 0 801 17,325 18,126 0.0280 0.0028 4.00 0.115 8 D3034 0.013 7.754 0.345 0.40 0.40 OK 227 1000 900 9 0 0 0 2,403 20,796 23,199 0.0359 0.0036 4.00 0.147 8 D3034 0.013 7,754 0.327 0.40 0.40 OK 2.60 900 900 18 0 0 0 4,806 23,199 28,005 0.0433 0.0043 4.00 0.178 8 D3034 0.013 7.754 0.351 0.40 0.40 OK 2.80 812 811 1.9 0 0 0 5,073 - 5,073 0.0078 0.0008 4.00 0.032 6 D3034 0.013 5.793 0.548 0.80 0.80 OK 1.18 811 810 9 0 0 0 2,403 5,073 7,476 0.0116 0.0012 4.00 0.047 6 D3034 0.013 5.793 0.599 0.80 0.80 OK 1.41 820 810 4 0 0 0 1,068 - 1,068 0.0017 0.0002 4.00 0.007 8 D3034 0.013 7.754 0.087 0.40 0.40 OK 0.89 810 800 4 0 0 0 1,068 8,544 9,612 0.0149 0.0015 4.00 0.061 8 D3034 0.013 7.754 0.292 0.40 0.40 OK 1.74 800 700 6 0 0 0. 1,602 37,617 39,219 0.0607 0.0061 4.00 0.249 10 D3034 0.013 9.692 0.254 0.30 0.30 OK 3.34 700 600 0 0 0 0 39,219 39,219 0.0607 0.0061 4.00 0.249 10 D3034 0.013 %92 0.254 0:30 0.30 OK 3.34 600 500 0 0 1.7 0 7,650 39,219 46,869 0.0725 0.0073 4.00 0.297 10 D3034 0.013 9.692 0.272 0.30 0.30 OK 3.60 500 400 8 0 0 0 2,136 80,244 82,380 0.1275 0.0127 4.00 0.523 1 12 1 D3034 0.013 11.538 0.234 0.25 0.25 OK 4.67 422 421 24 0 0 0 6,408 6,408 0.0099 0.0010 4.00 0.041 6 1 D3034 0.013 5.793 0.583 0.80 0.80 OK 131 421 420 12 0 0 0 3,204 6,408 9,612 0.0149 0.0015 4.00 0.061 6 D3034 0.013 5.793 0.649 0.80 0.80 OK 1.54 420 410 4 0 0 0 1,068 9,612 10,680 0.0165 0.000 4.00 0.068 6 D3034 0.013 5.793 0.706 0.80 0.80 OK L61 432 431 24 0 0 0 6,408 - 6,408 0.0099 0.0010 4.00 0.041 6 D3034 0.013 5.793 0.583 0.80 0.80 OK 1.31 431 430 12 0 0 0 3,204 6,408 9,612 0.0149 0.0015 4.00 0.061 6 D3034 0.013 5.793 0.649 0.80 0.80 OK 1.54 430 410 4 0 0 0 1,068 9,612 10,680 0.0165 0.0017 4.00 0.068 8 D3034 0.013 7.754 0.292 0.40 0.40 OK 1.82 410 400 0 0 0 0 21,360 21,360. 0.0330 0.0033 4.00 0.136 8 D3034 0.013 7.754 0.325 0.40 0.40 OK 2.50 400 300 8 0 0 0 2,136 103,740 105,876 0.1638 0.0164 4.00 0.672 12 D3034 0.013 11.538 0.316 0.25 OK 4.93 300 200 0 0 0 0 - 105,876 105,876 0.1638 0.0164 4.00 1 0.672 12 D3034 0.013 11.538 0.316 0.25 OK 4.93 203 202 28 0 0 0 7,476 - 7,476 0.0116 0.0012 4.00 1 0.047 6 D3034 0.013 5.793 0.599 0.80 0.80 OK 1.41 202 201 24 0 0 0 6,408 7476 13,884 0.0215 0,0021 4.00 0.088 6 D3034 0.013 5.793 0.650 0.80 0.80 OK 1.87 201 200 4 0 0 0 1,068 13,884 14,952 0.0231 0.0023 4.00 0.095 6 D3034 0.013 5.793 0.652 0.80 0.80 OK 1.94 200 100 0 0 0 0 - 120,828 120,828 0.1869 0.0187 4.00 0.766 12 D2241 0.013 11.77 0.200 0.25 0.20 OK 5.92 100 Ex16 0 0 0 0 - 120,828 120,828 0.1869 0.0187 4.00 0.766 12 D2241 0.013 11.77 0.200 0.25 0.20 OK 5.92 1301 1300 20 0 0 0 5,340 - 5,340 0.0083 0.0008 4.00 0.034 6 D3034 0.013 5.793 0.555 0.80 0.80 OK 1.21 1302 1300 19 0 0 0 5,073 5,073 0.0078 0.0008 4.00 0.032 6 D3034 0.013 5.793 0.548 0.80 0.80 OK 1.18 1300 Ex22 0 6 0 0 - 10413 1Q,413 0.0161 0.0016 4.00 0.066 6 D3034 0.013 5.793 0.703 0.80 0.80 OK 1.59 1400 ExBk 3 0 0 0 801 801 0.0012 0.0001 4.00 0.005 6 D3034 0,013 5.793 0.213 0.80 0.80 OK 0.68 Page 1 of 1