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THEBLUELINEGROUP.COM I MAIN [PHONE REDACTED] I 25 Central Way, Suite 400 I Kirkland, WA 98033 August 20, 2018 Heba Awad, PE City of Redmond 15670 NE 85th Street Redmond, WA 98052 RE: Hale Short Plat – Sewer Capacity Analysis – Third Review Blueline Job No. 17‐232 Dear Ms. Awad, This letter is in response to your review of the Hale Short Plat – Sewer Capacity Analysis. Below is a list of each comment from your comments we received on August 15, 2018 with our responses in bold. Backwater Calculation: 1. Pipe length and slope on the excel sheet needs to match the plan. Complete. See revised calculation spread sheets and plan sheet ASP‐01. 2. Recheck/revise rim elevations for all manholes. Complete. See revised calculation spread sheets and plan sheet ASP‐01. Plans: 1. Address all notes on the plan. Complete. See revised sheet ASP‐01. 2. Recalculate all pipe slopes based on the proposed MH rim elevations. Correct the plans and excel sheets based on new calculation Complete. Pipe slope labels on the plan sheet have been revised to match the calculation spreadsheets. See revised spread sheets and plan sheet ASP‐01. 3. The sewer of the eastern one third section of Lot 7A needs to go to the east instead of the west Complete. The eastern portion of tributary area 7A is now tributary to SSMH 28 which flows to the east. This resulted in a decrease of 2 total dwelling units within the study area. The Basin Area Exhibit has also been updated to reflect this change. See revised sheets SCA and ASP‐01. 4. Correct rim elevation for MH 15 Complete. The rim elevations have been updated and please note, the manhole numbers have changed. See revised sheet ASP‐01. 5. MH 10 needs to be revised to accommodate the sewer lines coming from the north based on the comprehensive plan Complete. Please note the manhole numbers have changed. See revised sheet ASP‐01. 6. Add information for MH 14 Information for all manholes within the study area have been added to the plan. Please note the manhole numbers have changed. See revised sheet ASP‐01. ---PAGE BREAK--- ---PAGE BREAK--- 17-232 PEAK PEAK MAX TRIBUTARY INFILTRATION HOURLY HOURLY AREA TRIBUTARY ZONING DENSITY DWELLING DEMAND PEAK INFLOW FLOW FLOW CUMULATIVE I.D. MANHOLE AREA (AC) DISTRICT PER AC1 UNITS (GPD)2 DEMAND3 (GPD)4 (GPD) (CFS) (CFS) - 2D3SMH576 0.0 0.368 - 2D3SMH574 0.0 0.368 1 2D3SMH572 0.4 RIN 5 2 420 1260 580 1840 0.003 0.368 2 2D3SMH570 0.6 RIN 5 3 630 1890 968 2858 0.004 0.365 3 2D3SMH568 8.2 RIN 5 41 8610 25830 12331 38161 0.059 0.360 4 2D3SMH564 5.0 RIN 5 25 5250 15750 7553 23303 0.036 0.259 5 2D3SMH562 4.2 RIN 5 21 4410 13230 6246 19476 0.030 0.223 6 2D3SMH560 1.5 RIN 5 8 1680 5040 2263 7303 0.011 0.192 - 2D3SMH532 0.0 RIN 5 0 0 0 0 0 0.000 0.181 7 EX SSMHA 5.9 RIN 5 30 6300 18900 8915 27815 0.043 0.181 8 SSMH1 1.9 RIN 5 10 2100 6300 2873 9173 0.014 0.092 9 SSMH2 1.2 RIN 5 6 1260 3780 1864 5644 0.009 0.078 10A SSMH3 0.3 R-1 1 1 210 [PHONE REDACTED] 0.002 0.069 10B, 10C SSMH3 5.1 RIN 5 25 5250 15750 7708 23458 0.036 0.067 11 SSMH4 0.6 RIN 5 3 630 1890 932 2822 0.004 0.031 12 SSMH5 1.2 RIN 5 6 1260 3780 1864 5644 0.009 0.027 13A SSMH6 1.4 R-1 1 1 [PHONE REDACTED] 2672 0.004 0.018 13B SSMH6 2.1 R-4 4 9 1890 5670 3186 8856 0.014 0.014 - SSMH8 0.0 RIN 5 0 0 0 0 0 0.000 0.046 14 SSMH9 1.2 RIN 5 6 1260 3780 1820 5600 0.009 0.046 15 SSMH10 1.8 RIN 5 9 1890 5670 2626 8296 0.013 0.038 16 SSMH11 1.6 RIN 5 8 1680 5040 2469 7509 0.012 0.025 17 SSMH12 1.9 RIN 5 9 1890 5670 2803 8473 0.013 0.013 - 2D3SMH566 0.0 RIN 5 0 0 0 0 0 0.000 0.043 18 2D3SMH556 1.6 RIN 5 8 1680 5040 2364 7404 0.011 0.043 - 2D3SMH554 0.0 RIN 5 0 0 0 0 0 0.000 0.031 - 2D3SMH552 0.0 RIN 5 0 0 0 0 0 0.000 0.031 - 2D3SMH550 0.0 RIN 5 0 0 0 0 0 0.000 0.031 19 2D3SMH548 1.1 RIN 5 6 1260 3780 1681 5461 0.008 0.031 20 SSMH 15 1.7 RIN 5 9 1890 5670 2555 8225 0.013 0.023 21 SSMH 16 1.4 RIN 5 7 1470 4410 2123 6533 0.010 0.010 TRIBUTARY FLOW CALCULATIONS FOR PROPOSED ALTERNATE SEWER ROUTE 1 RZC 21.08 2 210 GPD/DU (COR) 3 PEAKING FACTOR = 3 (COR) 4 INFILTRATION/INFLOW = 1,500 GPD/AC (COR) PROJECT NAME: PROJECT NUMBER: PREPARED BY: NWR & AJW HALE SHORT PLAT ---PAGE BREAK--- BACKWATER CALCULATIONS FOR PROPOSED ALTERNATE SEWER ROUTE Hale Short Plat NWR & AJW 17-232 ENTRANCE ENTRANCE EXIT OUTLET INLET APPROACH BEND JUNCTION UPSTREAM PIPE PIPE MANNING'S OUTLET INLET PIPE FULL VELOCITY TAILWATER FRICTION HGL HEAD HEAD CONTROL CONTROL VELOCITY HEAD HEAD HEADWATER RIM FROM TO Q LENGTH SIZE ELEVATION ELEVATION AREA VELOCITY HEAD ELEVATION LOSS ELEVATION LOSS LOSS ELEVATION ELEVATION HEAD LOSS LOSS ELEVATION ELEVATION FREEBOARD FLOW DEPTH CB CB (CFS) (FT) (IN) VALUE (FT) (FT) (SQ FT) (FT/SEC) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (IN) MH576 MH574 0.37 327 8 0.013 275.58 284.68 0.35 1.05 0.02 276.25 0.30 285.35 0.00 0.02 285.37 285.35 0.02 0.00 0.00 285.35 300.10 14.75 2.28 MH574 MH572 0.37 290 8 0.013 284.68 286.13 0.35 1.05 0.02 285.35 0.27 286.80 0.00 0.02 286.82 286.80 0.02 0.00 0.00 286.80 298.80 12.00 3.72 MH572 MH570 0.37 200 8 0.013 286.13 287.23 0.35 1.05 0.02 286.80 0.18 287.90 0.00 0.02 287.92 287.90 0.02 0.00 0.00 287.90 295.40 7.50 3.48 MH570 MH568 0.365 320 8 0.013 287.23 288.81 0.35 1.04 0.02 287.90 0.29 289.48 0.00 0.02 289.50 289.48 0.02 0.00 0.00 289.48 295.00 5.52 3.60 MH568 MH564 0.360 336 8 0.013 288.81 290.49 0.35 1.03 0.02 289.48 0.30 291.16 0.00 0.02 291.18 291.16 0.01 0.02 0.00 291.19 300.00 8.81 3.60 MH564 MH562 0.259 369 8 0.013 290.49 297.02 0.35 0.74 0.01 291.19 0.17 297.69 0.00 0.01 297.70 297.69 0.01 0.00 0.00 297.69 308.30 10.61 2.16 MH562 MH560 0.223 355 8 0.013 297.02 303.56 0.35 0.64 0.01 297.69 0.12 304.23 0.00 0.01 304.23 304.23 0.00 0.00 0.00 304.23 314.80 10.57 2.04 MH560 MH532 0.192 78 8 0.013 303.56 306.27 0.35 0.55 0.00 304.23 0.02 306.94 0.00 0.00 306.94 306.94 0.00 0.00 0.00 306.94 315.00 8.06 1.56 MH532 MHA 0.181 246 8 0.013 306.27 307.80 0.35 0.52 0.00 306.94 0.05 308.47 0.00 0.00 308.47 308.47 0.00 0.00 0.00 308.47 317.40 8.93 2.40 MHA MH1 0.181 298 8 0.013 307.80 309.30 0.35 0.52 0.00 308.47 0.07 309.97 0.00 0.00 309.97 309.97 0.00 0.00 0.00 309.97 322.00 12.03 2.52 MH1 MH2 0.092 275 8 0.013 309.30 312.10 0.35 0.26 0.00 309.97 0.02 312.77 0.00 0.00 312.77 312.77 0.00 0.00 0.00 312.77 325.00 12.23 1.56 MH2 MH3 0.078 271 8 0.013 312.10 314.80 0.35 0.22 0.00 312.77 0.01 315.47 0.00 0.00 315.47 315.47 0.00 0.00 0.00 315.47 328.10 12.63 1.44 MH3 MH4 0.069 348 8 0.013 314.80 316.50 0.35 0.20 0.00 315.47 0.01 317.17 0.00 0.00 317.17 317.17 0.00 0.00 0.00 317.17 326.20 9.03 1.56 MH4 MH5 0.031 152 8 0.013 316.50 318.00 0.35 0.09 0.00 317.17 0.00 318.67 0.00 0.00 318.67 318.67 0.00 0.00 0.00 318.67 330.00 11.33 0.84 MH5 MH6 0.027 148 8 0.013 318.00 319.50 0.35 0.08 0.00 318.67 0.00 320.17 0.00 0.00 320.17 320.17 0.00 0.00 0.00 320.17 330.10 9.93 0.84 MH6 MH7 0.018 346 8 0.013 319.50 329.90 0.35 0.05 0.00 320.17 0.00 330.57 0.00 0.00 330.57 330.57 0.00 0.00 0.00 330.57 339.50 8.93 0.48 MHA MH8 0.046 300 8 0.013 307.80 315.30 0.35 0.13 0.00 308.47 0.00 315.97 0.00 0.00 315.97 315.97 0.00 0.00 0.00 315.97 325.70 9.73 0.84 MH8 MH9 0.046 234 8 0.013 315.30 324.70 0.35 0.13 0.00 315.97 0.00 325.37 0.00 0.00 325.37 325.37 0.00 0.00 0.00 325.37 336.50 11.13 0.72 MH9 MH10 0.046 298 8 0.013 324.70 326.20 0.35 0.13 0.00 312.77 0.00 326.87 0.00 0.00 326.87 326.87 0.00 0.00 0.00 326.87 339.30 12.43 1.32 MH10 MH11 0.038 286 8 0.013 326.20 327.60 0.35 0.11 0.00 312.77 0.00 328.27 0.00 0.00 328.27 328.27 0.00 0.00 0.00 328.27 340.80 12.53 1.20 MH11 MH12 0.025 346 8 0.013 327.60 329.30 0.35 0.07 0.00 315.47 0.00 329.97 0.00 0.00 329.97 329.97 0.00 0.00 0.00 329.97 342.80 12.83 0.96 MH12 MH13 0.013 283 8 0.013 329.30 332.10 0.35 0.04 0.00 315.97 0.00 332.77 0.00 0.00 332.77 332.77 0.00 0.00 0.00 332.77 341.00 8.23 0.60 MH568 MH566 0.043 108 8 0.013 288.81 289.62 0.35 0.12 0.00 291.19 0.00 291.19 0.00 0.00 291.19 290.29 0.00 0.00 0.00 291.19 300.00 8.81 3.24 MH566 MH556 0.043 161 8 0.013 289.62 297.23 0.35 0.12 0.00 297.69 0.00 297.90 0.00 0.00 297.90 297.90 0.00 0.00 0.00 297.90 306.50 8.60 1.68 MH556 MH554 0.043 231 8 0.013 297.23 305.56 0.35 0.12 0.00 304.23 0.00 306.23 0.00 0.00 306.23 306.23 0.00 0.00 0.00 306.23 315.10 8.87 1.68 MH554 MH552 0.031 108 8 0.013 305.56 306.21 0.35 0.09 0.00 306.94 0.00 306.94 0.00 0.00 306.94 306.88 0.00 0.00 0.00 306.94 317.10 10.16 2.52 MH552 MH550 0.031 122 8 0.013 306.21 307.43 0.35 0.09 0.00 308.47 0.00 308.47 0.00 0.00 308.47 308.10 0.00 0.00 0.00 308.47 318.60 10.13 2.04 MH550 MH548 0.031 85 8 0.013 307.43 307.96 0.35 0.09 0.00 291.19 0.00 308.63 0.00 0.00 308.63 308.63 0.00 0.00 0.00 308.63 320.00 11.37 0.96 MH548 MH15 0.031 270 8 0.013 307.96 313.40 0.35 0.09 0.00 308.63 0.00 314.07 0.00 0.00 314.07 314.07 0.00 0.00 0.00 314.07 324.30 10.23 0.72 MH15 MH16 0.023 350 8 0.013 313.40 320.40 0.35 0.07 0.00 314.07 0.00 321.07 0.00 0.00 321.07 321.07 0.00 0.00 0.00 321.07 330.90 9.83 0.72 MH16 MH17 0.010 350 8 0.013 320.40 325.70 0.35 0.03 0.00 321.07 0.00 326.37 0.00 0.00 326.37 326.37 0.00 0.00 0.00 326.37 335.60 9.23 0.48 PIPE SEGMENT PREPARED BY: PROJECT NAME: PROJECT NUMBER: ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- 17-232 PEAK PEAK MAX TRIBUTARY INFILTRATION HOURLY HOURLY AREA TRIBUTARY TRIBUTARY ZONING DENSITY DWELLING DEMAND PEAK INFLOW FLOW FLOW CUMULATIVE I.D. MANHOLE AREA (SF) AREA (AC) DISTRICT PER AC1 UNITS (GPD)2 DEMAND3 (GPD)4 (GPD) (CFS) (CFS) A 0.372 2D3SMH574 0.372 1 2D3SMH572 16841.2489 0.4 RIN 5 2 420 1260 580 1840 0.003 0.372 2 2D3SMH570 28108.1136 0.6 RIN 5 3 630 1890 968 2858 0.004 0.369 3 2D3SMH568 [PHONE REDACTED] 8.2 RIN 5 41 8610 25830 12331 38161 0.059 0.364 4 2D3SMH564 [PHONE REDACTED] 5.0 RIN 5 25 5250 15750 7553 23303 0.036 0.263 5 2D3SMH562 [PHONE REDACTED] 4.2 RIN 5 20 4200 12600 6246 18846 0.029 0.227 6 2D3SMH560 65710.7832 1.5 RIN 5 8 1680 5040 2263 7303 0.011 0.197 2D3SMH532 0 0.0 RIN 5 0 0 0 0 0 0.000 0.186 7 SSMH1 279613.471 6.4 RIN 5 32 6720 20160 9629 29789 0.046 0.186 8 SSMH2 83434.5402 1.9 RIN 5 10 2100 6300 2873 9173 0.014 0.094 9 SSMH2.1 54126.9005 1.2 RIN 5 6 1260 3780 1864 5644 0.009 0.080 10B, 10C SSMH2.2 12799.1886 0.3 R-1 5 1 210 [PHONE REDACTED] 0.002 0.071 10A SSMH2.2 [PHONE REDACTED] 5.1 RIN 5 26 5460 16380 7708 24088 0.037 0.069 11 SSMH3 27052.0889 0.6 RIN 1 3 630 1890 932 2822 0.004 0.032 12 SSMH4 54132.1198 1.2 RIN 5 8 1680 5040 1864 6904 0.011 0.028 13A SSMH5 92526.2011 2.1 R-4 4 8 1680 5040 3186 8226 0.013 0.017 13B SSMH5 59311.6544 1.4 R-1 1 1 [PHONE REDACTED] 2672 0.004 0.004 14 SSMH7 52862.4636 1.2 RIN 5 6 1260 3780 1820 5600 0.009 0.046 15 SSMH7.1 76262.6796 1.8 RIN 5 9 1890 5670 2626 8296 0.013 0.038 16 SSMH7.2 90446.3906 2.1 RIN 5 10 2100 6300 3115 9415 0.015 0.025 17 SSMH7.3 62667.3381 1.4 RIN 5 7 1470 4410 2158 6568 0.010 0.010 18 SSMH 13 68660.4782 1.6 RIN 5 8 1680 5040 2364 7404 0.011 0.043 19 SSMH 14 48806.1614 1.1 RIN 5 6 1260 3780 1681 5461 0.008 0.031 20 SSMH 15 74193.8982 1.7 RIN 5 9 1890 5670 2555 8225 0.013 0.023 21 SSMH 16 61642.2478 1.4 RIN 5 7 1470 4410 2123 6533 0.010 0.010 TRIBUTARY FLOW CALCULATIONS FOR PROPOSED ALTERNATE SEWER ROUTE 1 RZC 21.08 2 210 GPD/DU (COR) 3 PEAKING FACTOR = 3 (COR) 4 INFILTRATION/INFLOW = 1,500 GPD/AC (COR) PROJECT NAME: PROJECT NUMBER: PREPARED BY: NWR & AJW HALE SHORT PLAT ---PAGE BREAK--- BACKWATER CALCULATIONS FOR PROPOSED ALTERNATE SEWER ROUTE Hale Short Plat NWR & AJW 17-232 ENTRANCE ENTRANCE EXIT OUTLET INLET APPROACH BEND JUNCTION PIPE PIPE MANNING'S OUTLET INLET PIPE FULL VELOCITY TAILWATER FRICTION HGL HEAD HEAD CONTROL CONTROL VELOCITY HEAD HEAD HEADWATER RIM FROM TO Q LENGTH SIZE ELEVATION ELEVATION AREA VELOCITY HEAD ELEVATION LOSS ELEVATION LOSS LOSS ELEVATION ELEVATION HEAD LOSS LOSS ELEVATION ELEVATION FREEBOARD FLOW DEPTH CB CB (CFS) (FT) (IN) VALUE (FT) (FT) (SQ FT) (FT/SEC) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (IN) MH A MH574 0.37 340 8 0.013 275.58 284.68 0.35 1.06 0.02 276.25 0.32 285.35 0.00 0.02 285.37 285.35 0.02 0.00 0.00 285.35 300.30 14.95 2.28 MH574 MH572 0.37 216 8 0.013 284.68 286.13 0.35 1.06 0.02 285.35 0.20 286.80 0.00 0.02 286.82 286.80 0.02 0.00 0.00 286.80 300.00 13.20 3.36 MH572 MH570 0.37 260 8 0.013 286.13 287.23 0.35 1.06 0.02 286.80 0.24 287.90 0.00 0.02 287.92 287.90 0.02 0.00 0.00 287.90 296.30 8.40 3.96 MH570 MH568 0.37 263 8 0.013 287.23 288.81 0.35 1.06 0.02 287.90 0.24 289.48 0.00 0.02 289.50 289.48 0.02 0.00 0.00 289.48 295.70 6.22 3.48 MH568 MH564 0.36 236 8 0.013 288.81 290.49 0.35 1.04 0.02 289.48 0.21 291.16 0.00 0.02 291.18 291.16 0.01 0.02 0.00 291.19 300.00 8.81 3.36 MH564 MH562 0.26 386 8 0.013 290.49 297.02 0.35 0.75 0.01 291.19 0.18 297.69 0.00 0.01 297.70 297.69 0.01 0.00 0.00 297.69 307.80 10.11 2.16 MH562 MH560 0.23 342 8 0.013 297.02 303.56 0.35 0.65 0.01 297.69 0.12 304.23 0.00 0.01 304.23 304.23 0.00 0.00 0.00 304.23 314.40 10.17 2.04 MH560 MH532 0.20 80 8 0.013 303.56 306.27 0.35 0.57 0.00 304.23 0.02 306.94 0.00 0.00 306.94 306.94 0.00 0.00 0.00 306.94 314.17 7.23 1.56 MH532 MH1 0.19 220 8 0.013 306.27 307.90 0.35 0.53 0.00 306.94 0.05 308.57 0.00 0.00 308.57 308.57 0.00 0.00 0.00 308.57 317.00 8.43 2.28 MH1 MH2 0.19 284 8 0.013 307.90 309.30 0.35 0.53 0.00 308.57 0.07 309.97 0.00 0.00 309.97 309.97 0.00 0.00 0.00 309.97 317.30 7.33 2.52 MH2 MH2.1 0.09 261 8 0.013 309.30 310.61 0.35 0.27 0.00 309.97 0.02 311.27 0.00 0.00 311.27 311.27 0.00 0.00 0.00 311.27 325.00 13.73 1.80 MH2.1 MH2.2 0.08 257 8 0.013 310.61 311.89 0.35 0.23 0.00 311.27 0.01 312.56 0.00 0.00 312.56 312.56 0.00 0.00 0.00 312.56 328.10 15.54 1.68 MH2.2 MH3 0.07 334 8 0.013 311.89 313.70 0.35 0.20 0.00 312.56 0.01 314.37 0.00 0.00 314.37 314.37 0.00 0.00 0.00 314.37 326.00 11.63 1.56 MH3 MH4 0.03 139 8 0.013 313.70 319.70 0.35 0.09 0.00 314.37 0.00 320.37 0.00 0.00 320.37 320.37 0.00 0.00 0.00 320.37 330.00 9.63 0.60 MH4 MH5 0.03 134 8 0.013 319.70 321.40 0.35 0.08 0.00 320.37 0.00 322.07 0.00 0.00 322.07 322.07 0.00 0.00 0.00 322.07 330.00 7.93 0.84 MH5 MH6 0.02 332 8 0.013 321.40 331.40 0.35 0.05 0.00 322.07 0.00 332.07 0.00 0.00 332.07 332.07 0.00 0.00 0.00 332.07 340.00 7.93 0.48 MH1 MH7 0.05 520 8 0.013 307.90 326.10 0.35 0.13 0.00 308.57 0.01 326.77 0.00 0.00 326.77 326.77 0.00 0.00 0.00 326.77 336.40 9.63 0.84 MH7 MH7.1 0.04 284 8 0.013 326.10 327.52 0.35 0.11 0.00 309.97 0.00 328.19 0.00 0.00 328.19 328.19 0.00 0.00 0.00 328.19 339.30 11.11 1.20 MH7.1 MH7.2 0.02 272 8 0.013 327.52 328.88 0.35 0.07 0.00 311.27 0.00 329.55 0.00 0.00 329.55 329.55 0.00 0.00 0.00 329.55 340.80 11.25 0.96 MH7.2 MH7.3 0.01 332 8 0.013 328.88 330.54 0.35 0.03 0.00 312.56 0.00 331.21 0.00 0.00 331.21 331.21 0.00 0.00 0.00 331.21 342.70 11.49 0.96 MH7.3 MH8 0.00 269 8 0.013 330.54 333.30 0.35 0.00 0.00 326.77 0.00 333.97 0.00 0.00 333.97 333.97 0.00 0.00 0.00 333.97 340.90 6.93 0.12 MH568 MH13 0.04 250 8 0.013 288.81 297.56 0.35 0.12 0.00 291.19 0.00 298.23 0.00 0.00 298.23 298.23 0.00 0.00 0.00 298.23 306.20 7.97 0.72 MH13 MH14 0.03 300 8 0.013 297.56 308.36 0.35 0.09 0.00 298.23 0.00 309.03 0.00 0.00 309.03 309.03 0.00 0.00 0.00 309.03 317.30 8.27 0.60 MH14 MH15 0.02 440 8 0.013 308.36 314.96 0.35 0.07 0.00 309.03 0.00 315.63 0.00 0.00 315.63 315.63 0.00 0.00 0.00 315.63 323.90 8.27 0.72 MH15 MH16 0.01 310 8 0.013 314.96 320.54 0.35 0.03 0.00 315.63 0.00 321.21 0.00 0.00 321.21 321.21 0.00 0.00 0.00 321.21 329.74 8.53 0.48 MH16 MH17 0.00 420 8 0.013 320.54 326.84 0.35 0.00 0.00 321.21 0.00 327.51 0.00 0.00 327.51 327.51 0.00 0.00 0.00 327.51 335.70 8.19 0.12 PIPE SEGMENT PREPARED BY: PROJECT NAME: PROJECT NUMBER: ---PAGE BREAK--- THEBLUELINEGROUP.COM I MAIN [PHONE REDACTED] I 25 Central Way, Suite 400 I Kirkland, WA 98033 May 25, 2018 Jeanne Justice, PE City of Redmond 15670 NE 85th Street Redmond, WA 98052 Hale Short Plat – Sewer Capacity Analysis LAND‐2017‐01062 Dear Ms. Justice: Blueline has prepared a sewer capacity analysis of the 8‐inch sewer main in 134th Ave NE and NE 100th St located in the western portion of the NE 100th St Basin. The analysis was prepared to determine if the existing system is capable of serving additional areas as indicated on the attached Basin Area Exhibit. From review of the City of Redmond’s 2012 Comprehensive Plan (Figure 4‐15, attached) we understand that the proposed sewer improvements associated with the Hale Short Plat project (LAND‐2017‐01062) are planned to tie into a sewer system that would be installed in NE 104th St that would be routed east to 136th Ave NE and south to NE 100th St. At this time, there is no existing sewer main in NE 104th St or 136th Ave NE as shown on the City’s Figure 4‐15. In order to provide sewer as shown on the City’s Comp. Plan, the Hale Short Plat project would need to install approximately 750‐feet of sewer main in NE 104th St and approximately 1,350‐feet of sewer main in 136th Ave NE to tie into the existing sewer system. An alternate sewer connection for the Hale Short Plat proposes to connect the projects sewer improvements to the existing sewer main in 134th Ave NE approximately 250‐ft south. This alternate sewer route would only require approximately 300‐feet of sewer main to be installed in NE 104th St to tie into the existing system. Sewer from the Hale Short Plat project would then be routed south along 134th Ave NE then east via NE 100th St for a total of approximately 2,150‐feet before combining with the City’s planned sewer routing near the intersection of 136th Ave NE and NE 100th St (see Alternate Sewer Routing Exhibit, attached). A capacity analysis has been prepared for the existing main along 134th Ave NE and NE 100th St to ensure they have sufficient capacity to accept additional flows from the tributary areas shown on the Sewer Capacity Analysis exhibit. This analysis assumes the alternate sewer connection described above is implemented in place of the one shown on the City’s Comp. Plan. In the analysis, tributary areas were delineated based on existing topography and developable area within the basin. The maximum number of dwelling units was calculated based on maximum density allowed by zoning for all parcels within the tributary area. In this case, the tributary areas are zoned ---PAGE BREAK--- either R‐1 Residential, R‐4 Residential, or RIN Residential, meaning 1, 4, or 5 dwelling units per acre respectively. Residential sewer generation rates of 210‐gallons per unit per day were utilized to develop the overall sewer flow. A peaking factor of 3 was applied to these flows to generate peak hour flows from the tributary area. In addition, inflow and infiltration was added at a rate of 1,500‐gallons per acre per day. The infiltration and inflow component was not assigned a peaking factor but added directly to the total flow. The overall peak hour sewer generation for the study area will be approximately 0.372‐cubic feet per second at buildout. The minimum slope along the existing system within the study area was found to be 0.0046‐ft/ft. Based on this slope, the maximum capacity for the 8‐inch main was calculated to be 0.820‐cubic feet per second indicating that the proposed alternate sewer connection has sufficient capacity to serve the additional areas as shown on the Basin Area Exhibit and will not impact any future development. Below is the list of items the City requested along with responses to each in bold: Provide a sewer capacity analysis that shows the capacity of the existing lines, without need to reconstruct portions already built. Sewer capacity calculations are shown on the Basin Area Exhibit. The capacity of the existing lines was calculated to be 0.820‐cubic feet per second and the calculated peak hour sewer generation was 0.372‐cubic feet per second. o Include entire northwestern area of NE 100th St basin draining to the intersection of 134th Ave NE and NE 104th St (proposed manhole 2D3SMH530). Provide a map of the area (with contours) identifying each parcel remaining in the basin and which sewer line each parcel would discharge to. The northwestern area of the NE 100th St Basin tributary to the intersection of 134th Ave NE and NE 104th St has been included in the capacity analysis. See Basin Area Exhibit for areas included in the capacity analysis. o Define eastern limits for lots fronting NE 104th St draining to 134th Ave NE. The eastern limits for lots fronting NE 104th St tributary to 134th Ave NE are shown on the Basin Area Exhibit. ---PAGE BREAK--- o Include development potential of parcels south of NE 100th St flowing to the existing 100th line at the proposed manhole 2D3SMH583 to be constructed with the proposed Rosehill Subdivision. Provide a map of the area (with contours) identifying each parcel remaining in the NE 95th St basin that will be redirecting the discharge to the NE 100th St basin. Parcels included in the capacity analysis south of NE 100th St are shown on the Basin Area Exhibit. o Provide a spreadsheet that identifies each (undeveloped and underdeveloped) parcel in the basin and the potential number of lots based on the current zoning and estimated flow. The flow generated from each parcel should include a single family flow of 210 gpd and a peaking factor of 3. The Basin Area Exhibit graphically shows all parcels included in the capacity analysis. It also includes a spreadsheet showing the potential maximum number of dwelling units per current zoning and corresponding demands based on the criteria given above. o Flows should also include I/I for the basin of 1500 gpad. Infiltration and inflow of 1,500 gpd/ac is included in the peak hourly flow calculation shown on the Basin Area Exhibit. o Analyze each pipe segment between manholes and determine the capacity and percent full of the development. Analysis should be from 2D3SMH530 to 2D3SMH584. The existing sewer system between 2D3SMH530 and 2D3SMH584 was reviewed and the worst‐case pipe slope was found to be 0.0046‐ft/ft between 2D3SMH568 and 2D3SMH570. The capacity calculations provided on the Basin Area Exhibit are based on this segment of existing pipe and by inspection, all other existing pipes within the study area have sufficient capacity to convey the calculated demands. Verify the amendment would produce no adverse environmental impact, substantially equivalent (or improved) environmental protection as would be provided if the current plan were implemented. The proposed alternate sewer route is expected to have the same environmental impact/protection as would be provided if the current plan were implemented. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " 134th AVE NE 136th AVE NE NE 104th ST 138th AVE NE L NE 95th LN NE 103rd ST NE 109th PL NE 102nd ST 133rd AVE NE NE 100th ST NE 108th ST 131st AVE NE NE 97th ST Sammamish River River Trail Park P.S.P. & L. CO. PUGET SOUND POWER & LIGHT ROW PUG NE 95th ST NE 108th ST NE 93rd ST NE 110th PL NE 94th ST NE 108th PL NE 97th ST 152nd CT NE NE 110th CT NE 107th WY 148th AVE NE 153rd AVE NE NE 92nd ST NE 92nd WY NE 93rd CT 155th AVE NE 153rd CT NE 151st CT NE 154th PL NE NE 92 155th PL NE 147th AVE NE 150th NE 107th ST 155th PL 151st AVE NE 155th PL NE 135th PL NE NE 93rd ST AVE NE 138th CT NE 139th CT NE NE 111th ST 154th AVE NE 154th PL NE NE 106th ST NE 111th CT 153rd AVE NE NE 112th ST NE 106th WY NE 113th ST WILLOWS RD WILLOWS RD W IL L O W S R D WILLOWS RD NE 100th Street Basin Figure 4 - 15 NE 100th Street Basin WWCompPlanBasinNE100.mxd Draft Date 02/11/09 ¾ À 100-12 ¾ À 100-11 ¾ À 100-10 ¾ À 100-13 ¾ À 100-14 ¾ À 100-15 ¾ À 100-9 ¾ À 100-8 ¾ À 100-7 ¾ À 100-6 ¾ À 100-2 ¾ À 100-1 ¾ À 100-5 ¾ À 100-4 ¾ À 100-3 NE 95th Street Basin North Willows Road Basin Valley Estates Basin Meadow Park Basin Disclaimer: This map is created and maintained by the City of Redmond, for reference purposes only. The City makes no guarantee as to the accuracy or completeness of the features shown on this map. Legend ®ç Gravity Pipe Force Main Pipe City Limit Basin Service Area Neighborhood Sewer Area Under Construction Joint Use Other Agency Proposed City of Redmond Private ! ! ! King County City of Redmond Private Under Construction Joint Use Other Agency King County Parks and Open Space " " " " " " " Pump Station 0 300 600 900 Scale: 1" = 600' Grinder Pump Neighborhood ---PAGE BREAK--- Sewer Serviced by 134th St Sewer Serviced by 136th St Alternate Sewer Routing Exhibit