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Home My WebLink AboutRS_TIR Addendum_20231108_v1©2023 D. R. STRONG Consulting Engineers Inc. ADDENDUM TO TECHNICAL INFORMATION REPORT for SNYDER PROPERTY 13229 & 13233 158th Avenue SE, Renton, Washington _________________________________________________________________________ DRS Project No. 21155 Renton File No. C22003859 Applicant Justin Lagers NW Seattle Builders, LLC 9675 SE 36th Street, Suite 105 Mercer Island, WA 98040 Report Prepared by D. R. STRONG Consulting Engineers, Inc. 620 7th Avenue Kirkland WA 98033 (425) 827-3063 Report Issue Date October 31, 2023 10-31-23 ©2023 D. R. STRONG Consulting Engineers Inc. Snyder Property City of Renton ADDENDUM TO TECHNICAL INFORMATION REPORT SNYDER PROPERTY AS-BUILT CAPACITY ANALYSIS ©2023 D. R. STRONG Consulting Engineers Inc. Snyder Property City of Renton The following is an analysis performed for the constructed storm system along the frontage improvements. The proposed conveyance system had a minimum pipe slope of 1.38 %. The minimum slope was constructed at 0.56%. A backwater analysis was performed in order to confirm that the conveyance system had the capacity to convey the 100-year storm without any overtopping. The 100-year storm for the upstream area is 3.58 cfs. A starting headwater elevation of 512.42 was assumed for the system. This assumes that the downstream ditch that the conveyance system discharges to is one- foot deep (water elevation at crown of pipe). As shown below in the backwater analysis, there is no overtopping of any rim elevations throughout the system under the combined 100-year flow. ©2023 D. R. STRONG Consulting Engineers Inc. Snyder Property City of Renton Backwater Analysis R=100 -year storm aR=2.61 bR=0.63 PR=4 inches Conveyance System Variables: d=pipe diameter n=Manning's Number l=length of pipe PipeStructures Subasins &A A C CC Tc iR IR QR SQR Q - d Material n l Slope invert invert over-Q V Bend CB Tributaries subasin Ratio in out flow Full Full Dia elev.Flow Flow FROM CB To CB sf Ac Ac Min.cfs cfs in ft %ft ft ft cfs fps CB#1 TO DITCH INLET 1 1 2 1 0 0.00 0.90 6.3 0.82 3.27 0.00 3.58 0.00 12 DI 0.012 12 19.17 514.69 512.39 516.86 16.94 21.57 0 2 2 2 3 2 200 0.00 0.90 6.3 0.82 3.27 0.01 3.59 0.00 12 DI 0.012 111 0.56 512.11 511.49 516.85 2.89 3.68 17 2 3 3 DITCH INLET 3 3050 0.07 0.74 6.8 0.78 3.12 0.16 3.75 0.04 12 DI 0.012 11 0.64 511.49 511.42 513.68 3.09 3.93 28 2 ©2023 D. R. STRONG Consulting Engineers Inc. Snyder Property City of Renton BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#1 TO DITCH INLET.bwp Surcharge condition at intermediate junctions Tailwater Elevation:512.42 feet Discharge Range:1. to 3.75 Step of 0.138 [cfs] Overflow Elevation:516.86 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 11 LF - 12"CP @ 0.64% OUTLET: 511.42 INLET: 511.49 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 513.68 BEND: 28 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.04 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.00 0.96 512.45 * 0.012 0.43 0.40 1.00 1.00 0.94 0.96 0.57 1.14 0.97 512.46 * 0.012 0.45 0.43 1.00 1.00 0.94 0.97 0.62 1.28 0.98 512.47 * 0.012 0.48 0.45 1.00 1.00 0.94 0.98 0.66 1.41 0.99 512.48 * 0.012 0.51 0.48 1.00 1.00 0.95 0.99 0.69 1.55 1.00 512.49 * 0.012 0.53 0.51 1.00 1.00 0.95 1.00 0.73 1.69 1.01 512.50 * 0.012 0.56 0.53 1.00 1.00 0.95 1.01 0.77 1.83 1.02 512.51 * 0.012 0.58 0.56 1.00 1.00 0.95 1.02 0.80 1.96 1.04 512.53 * 0.012 0.60 0.59 1.00 1.00 0.96 1.04 0.84 2.10 1.05 512.54 * 0.012 0.62 0.61 1.00 1.00 0.96 1.05 0.87 2.24 1.07 512.56 * 0.012 0.64 0.64 1.00 1.00 0.97 1.07 0.90 2.38 1.09 512.58 * 0.012 0.66 0.66 1.00 1.00 0.97 1.09 0.94 2.51 1.11 512.60 * 0.012 0.68 0.69 1.00 1.00 0.98 1.11 0.97 2.65 1.12 512.61 * 0.012 0.70 0.72 1.00 1.00 0.98 1.12 1.00 2.79 1.15 512.64 * 0.012 0.72 0.75 1.00 1.00 0.99 1.15 1.03 2.93 1.16 512.65 * 0.012 0.74 0.78 1.00 1.00 0.99 1.16 1.06 3.06 1.19 512.68 * 0.012 0.76 0.82 1.00 1.00 1.00 1.19 1.10 3.20 1.14 512.63 * 0.012 0.77 0.87 1.00 1.00 0.87 1.14 1.14 3.34 1.24 512.73 * 0.012 0.79 1.00 1.00 1.00 1.02 1.24 1.19 3.48 1.26 512.75 * 0.012 0.80 1.00 1.00 1.00 1.02 1.26 1.23 3.61 1.29 512.78 * 0.012 0.82 1.00 1.00 1.00 1.03 1.29 1.28 3.75 1.32 512.81 * 0.012 0.83 1.00 1.00 1.00 1.04 1.32 1.32 PIPE NO. 2: 111 LF - 12"CP @ 0.56% OUTLET: 511.49 INLET: 512.11 INTYP: 5 JUNC NO. 2: OVERFLOW-EL: 516.85 BEND: 17 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.96 0.61 512.72 * 0.012 0.42 0.40 0.96 0.96 0.47 0.61 0.56 1.09 0.65 512.76 * 0.012 0.44 0.43 0.97 0.97 0.49 0.65 0.60 1.22 0.69 512.80 * 0.012 0.47 0.46 0.98 0.98 0.51 0.69 0.63 1.35 0.73 512.84 * 0.012 0.50 0.49 0.99 0.99 0.55 0.73 0.67 1.48 0.76 512.87 * 0.012 0.52 0.51 1.00 1.00 0.58 0.76 0.70 1.62 0.79 512.90 * 0.012 0.54 0.54 1.01 1.01 0.61 0.79 0.74 1.75 0.82 512.93 * 0.012 0.57 0.57 1.02 1.02 0.64 0.82 0.77 1.88 0.85 512.96 * 0.012 0.59 0.59 1.04 1.04 0.68 0.85 0.80 2.01 0.89 513.00 * 0.012 0.61 0.62 1.05 1.05 0.72 0.89 0.83 2.14 0.92 513.03 * 0.012 0.63 0.65 1.07 1.07 0.77 0.92 0.86 2.27 0.96 513.07 * 0.012 0.65 0.67 1.09 1.09 0.82 0.96 0.89 2.40 1.00 513.11 * 0.012 0.67 0.70 1.11 1.11 0.88 1.00 0.92 2.54 1.06 513.17 * 0.012 0.69 0.73 1.12 1.12 0.95 1.06 0.94 2.67 1.17 513.28 * 0.012 0.71 0.76 1.15 1.15 1.06 1.17 0.97 ©2023 D. R. STRONG Consulting Engineers Inc. Snyder Property City of Renton 2.80 1.24 513.35 * 0.012 0.72 0.80 1.16 1.16 1.13 1.24 1.00 2.93 1.34 513.45 * 0.012 0.74 0.84 1.19 1.19 1.21 1.34 1.03 3.06 1.37 513.48 * 0.012 0.76 0.90 1.14 1.14 1.22 1.37 1.05 3.19 1.54 513.65 * 0.012 0.77 1.00 1.24 1.24 1.38 1.54 1.09 3.33 1.63 513.74 * 0.012 0.79 1.00 1.26 1.26 1.47 1.63 1.13 3.46 1.74 513.85 * 0.012 0.80 1.00 1.29 1.29 1.56 1.74 1.17 3.59 1.86 513.97 * 0.012 0.81 1.00 1.32 1.32 1.66 1.86 1.21 PIPE NO. 3: 12 LF - 12"CP @ 19.17% OUTLET: 512.39 INLET: 514.69 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.95 0.48 515.17 * 0.012 0.41 0.17 0.33 0.33 0.41 ***** 0.48 1.08 0.53 515.22 * 0.012 0.44 0.18 0.37 0.37 0.44 ***** 0.53 1.22 0.57 515.26 * 0.012 0.47 0.19 0.41 0.41 0.47 ***** 0.57 1.35 0.62 515.31 * 0.012 0.50 0.20 0.45 0.45 0.50 ***** 0.62 1.48 0.66 515.35 * 0.012 0.52 0.20 0.48 0.48 0.52 ***** 0.66 1.61 0.70 515.39 * 0.012 0.54 0.21 0.51 0.51 0.54 ***** 0.70 1.74 0.74 515.43 * 0.012 0.57 0.22 0.54 0.54 0.57 ***** 0.74 1.87 0.78 515.47 * 0.012 0.59 0.23 0.57 0.57 0.59 ***** 0.78 2.00 0.83 515.52 * 0.012 0.61 0.24 0.61 0.61 0.61 ***** 0.83 2.13 0.87 515.56 * 0.012 0.63 0.24 0.64 0.64 0.63 ***** 0.87 2.26 0.91 515.60 * 0.012 0.65 0.25 0.68 0.68 0.65 ***** 0.91 2.40 0.95 515.64 * 0.012 0.67 0.26 0.72 0.72 0.67 ***** 0.95 2.53 0.99 515.68 * 0.012 0.69 0.27 0.78 0.78 0.69 ***** 0.99 2.66 1.03 515.72 * 0.012 0.70 0.27 0.89 0.89 0.70 ***** 1.03 2.79 1.08 515.77 * 0.012 0.72 0.28 0.96 0.96 0.72 ***** 1.08 2.92 1.12 515.81 * 0.012 0.74 0.29 1.06 1.06 0.74 ***** 1.12 3.05 1.17 515.86 * 0.012 0.75 0.29 1.09 1.09 0.75 ***** 1.17 3.18 1.23 515.92 * 0.012 0.77 0.30 1.26 1.26 0.77 ***** 1.23 3.31 1.28 515.97 * 0.012 0.78 0.31 1.35 1.35 0.78 ***** 1.28 3.44 1.34 516.03 * 0.012 0.80 0.31 1.46 1.46 0.80 ***** 1.34 3.58 1.40 516.09 * 0.012 0.81 0.32 1.58 1.58 0.81 ***** 1.40