6027 GLENWOOD AVE 2025-07-28 - Laserfiche WebLink

• Section 3 Site Development The site was visited on September 19,2012. The downstream drainage system was field verified and the drainage patterns and ground cover were observed. The site consists of a vacant lot with grass and fir trees. To the south is a low area. To the west is Glenwood Avenue which has curbs and gutters,but is higher than the site. To the North is Seahurst Avenue which does not have curbs or gutters and slopes down to the east. To the East is a residential lot that does not drain to the site. A quarter mile downstream inspection was performed. The inspection concluded no visual impacts or potential problems will occur from the development of the subject site. The downstream course consists of sheet flow into the existing vegetated and or gravel shoulder of Seahurst Avenue. The water would infiltrate or flow along the shoulder for several hundred feet until it enters a concrete gutter and then a catch basin,piped drainage and roadside ditch. The flow is piped under 60th Street and then enters a gully. Splashblocks will be used to provide basic dispersion for the roof downspouts. A catch basin in the driveway will collect runoff from the driveway which will drain to an infiltration trench along the northeast side of the site.The stormwater will either infiltrate or overflow and be dispersed over the grass yard and sheet flow off site as it does now. This is the only practical method of storm water control as the soils are not suitable for full infiltration and there is no storm drain to connect to.A drain manhole is located at the northeast corner of the lot. Section 4 Stormwater Pollution Prevention Plan The site does not require any special stormwater pollution prevention. See attached SPPP. Section 5 Source Control of Pollution Due to the small size of this project and residential nature of this project no significant amount of Pollution will be generated. The roof downspouts will be dispersed over the grass yard to prevent mixing with the water from the driveway. The driveway runoff will be collected by a catch basin and drained to an infiltration/dispersion trench. The catch basin will have a downturned elbow to provide some pollution protection. The infiltration and dispersion will provide treatment of the stormwater. The infiltration trench will connect to the storm manhole at the northeast corner of the site. Any overflow from the infiltration trench will go into the storm manhole. Section 6 Special Reports and Studies No special reports or studies are available on this site. The SCS Soil Map lists the soils as Alderwood(6). A soil hole dug by Anstey Engineering confirmed the Gravelly Sandy Loam nature of the soil. Section 7 Other Permits A Building Permit is associated with this project to build the duplex. 2