3530 COLBY AVE 2016-05-19 - Laserfiche WebLink

DETENTION DESIGN The following data represents the input and results for sizing a detention tank using the SBUH method and the StormShed program. The predeveloped condition was 100% grass and the post developed condition all impervious. The release rate goals were 100% of the 2, 10 and 100 year storm as directed by the staff, since the discharge is to a combined sewer system. A goal of 50% of the 2 year storm was entered into StormShed, but that goal could not be reached due to the small area being detained. Thus the goal of 100%of the 2 year was used. Project Precips [2 yr] 1.55 in [10 yr] 2.25 in [100 yr] 3.25 in HOYT-C PRE Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event (cfs) (hrs) (ac-ft) ac /Loss HOYT-C PRE 0.01 8.17 0.0066 0.15 SBUH/SCS TYPEIA 2 yr HOYT-C PRE 0.03 8.00 0.0130 0.15 SBUH/SCS TYPEIA 10 yr HOYT-C PRE 0.06 8.00 0.0235 0.15 SBUH/SCS TYPEIA 100 yr Drainage Area: HOYT-C PRE Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.1500 ac 86.00 0.27 hrs Impervious 0.0000 ac 0.00 0.00 hrs Total 0.1500 ac Supporting Data: Pervious CN Data: PREDEV GRASS 86.00 0.1500 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet OVERLAND GRASS 99.00 ft 3.50% 0.2400 13.97 min HOYT-C POS Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event (cfs) (hrs) (ac-ft) ac /Loss HOYT-C POS 0.05 8.00 0.0166 0.15 SBUH/SCS TYPE1A 2 yr HOYT-C POS 0.07 8.00 0.0253 0.15 SBUH/SCS TYPEIA 10 yr HOYT-C POS 0.11 8.00 0.0377 0.15 SBUH/SCS TYPEIA 100 yr Drainage Area: HOYT-C POS Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.0000 ac 86.00 0.00 hrs Impervious 0.1500 ac 98.00 0.11 hrs Total 0.1500 ac Supporting Data: Impervious CN Data: 3011 Raven Crest,Bellingham,WA 98226 425-481-9687 (-4/6