4817 RUCKER AVE 2024-12-09 - Laserfiche WebLink

See Volume 5 Chapter 5 and 1-4 UIC Program for run-off treatment required for infiltration facilities. Infiltration facilities with a perforated pipe is considered a UIC well (per V1, Ch.4, S. 1-4.1) Register UIC well using Ecology's online registration process. See the following website for details: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Underground-iniection- control-program/Register-UIC-wells-online Perforated pipe removed from facility, therefore no longer a UIC Confirm if offsite areas from the south will be flowing into the site, based on the contours shown, it appears that it does. Will this flow end up in the infiltration facility? Subsequent field investigation verified no upslope contributing surface runoff from any direction. The catch basin downstream of the infiltration facility shall be provided with gas trap (prior to discharge to the sewer). Added It looks like there is an error in the two elevations listed for the infiltration facility. In the plan sheet,the inner elipse is shown at a higher elevation (303.2) than the outer elipse (296.7). This is top and bottom of the free draining rock layer and the elevations should be switched in the plan drawing. This is the opposite of what is shown in detail 1003. Corrected Plan Note 12—do not call out detail 1203 for the 12" slotted pipe. Detail does not apply for this pipe. Provide section view of infiltration facility(detail 1209 missing). Corrected and added Detail 1003: Extend free draining rock layer to at least 6-inches above the slotted PVC pipe. Done Line sides of infiltration facility with permeable filter fabric, See V5, Ch 5, BMP-T7.20 Done Provide Detail 1209 for the Section view of the infiltration facility,for review. Added Stormwater Management Report: SWPPP/TESC plan- Protect infiltration facility from sediment runoff generated during construction. See section II-7.0 of the Geotechnical Engineering Report. Added interceptor Swale to divert flows away from facility during construction and note on plan to not connect inlet pipe into facility until site is stabilized. MR#5 isn't required under the new stormwater ordinance for the combined sewer area. Removed MR6:Artificial turf is considered by Ecology to be a pollution generating surface (see PGPS definition pg 1073, Ecology manual). Treatment is required for the storm flows from the rubber playground surface that discharge to the infiltration facility. Treatment is not required for flows that discharge to the combined sewer system. Treatment requirements will be dependent on what type of material is used for the playground surfacing. Please provide this information per my previous email. See earlier response MR 7:The project is in the combined sewer area and adds over 200 sf of net new impervious area. The City's Ordinance related to Stormwater Controls in the Combined Sewer Area applies. See Section 6.10 of the DCSS. Per section 6.10 of the DCSS,flow control will be required and shall comply with the following standard: • Storm water discharges shall match developed discharge durations to existing site durations for the range of existing discharge rates from the 10-year peak flow through the full 100-year peak flow. (note that this requirement is different than what was modeled for this project) Update drainage calculation section for these thresholds. WWHM updated