931 BROADWAY TEUTSCH STUDENT HOUSING 2018-03-07

Minimum Requirement#8-Wetlands Protection This project is not proposing to discharge stormwater directly or indirectly in to a wetland, and therefore this requirement does not apply. Minimum Requirement#9-Operation and Maintenance An Operations and Maintenance plan of permanent stormwater control facilities has been prepared. See Section 8.7 of this report for additional detail. 2 SITE ASSESSMENT The following sections outline the existing conditions of the project site and surrounding areas. _ 2.1 TOPOGRAPHY This site slopes generally towards the northeast corner of the site. The Broadway Ave frontage is generally flat,while the 10t"St frontage slopes at an average grade of 6.5%towards the east. Site elevations range approximately 12 feet across the site. Due to the grade change, there are several retaining walls onsite. The access to the existing building from the alley connecting to 10`h St is at the lower level of the building,while access from Broadway Ave is to the upper level. The site has an unusually large setback of approximately 41 feet from the Broadway Ave roadway to the west property line. 2.2 EXISTING DRAINAGE Stormwater runoff from the roof is collected via downspouts, and runoff from the parking area and concrete walkways is collected by area drains and catch basins. The runoff is conveyed to a side sewer,which discharges to the existing 8" public combined sewer main in Broadway Ave. Any other surface runoff is assumed to sheet flow offsite. No detention structures are known. 2.3 Soi�s � A subsurface investigation and geotechnical evaluation was completed for this project by PanGEO, Inc. in November 2015. Three test borings were completed onsite, revealing 2.5-5.0 feet . of undocumented fill overlying very dense glacial till. It is recommended that permanent cut and fill slopes be constructed no steeper than 2H:1V. Although infiltration potential was not specifically evaluated during the subsurface explorations,the presence of very dense glacial till indicate that there is little potential for permanent infiltration for stormwater control. No groundwater was encountered during the subsurface exploration of the site. It is anticipated that any groundwater seepage rates will be minor. This site is located near the Everett Smelter Site/Asarco cleanup area. The Department of Ecology map of the cleanup area was reviewed, and confirmed that the site is outside the boundary of the cleanup area. However, sites that are outside of the boundary but near the cleanup area are more likely to have soils that contain arsenic and/or lead that exceed the cleanup level, particularly in EVCC STUDENT HOUSING-STORMWATER SITE PLAN-REVISED.DOCX 5 �