7125 EVERGREEN WAY 2018-01-02 MF Import

OFF-SITE ANALYSIS The downstream drainage system for the subject site was investigated for approximately '/< mile on 3/9/99. Weather conditions for ihe weeks prior to the investigation consisted of heavy, continual precipitation. The extent of the drainage system investigated consists entirely of underground conveyance systems. Observations of this system are therefore limitec: to evidence of overtopping or flooding and/or silted or clogged strucriues. The downstream conveyance system generally runs north along Rainier Drive across Tereve and Madison and then continues north behind the Albertsons simated on the corner of Madison and Evergreen Way. Eventua]ly this system dischazges to the Alderwood Pump Station. At the time of investigation there were not any obvious problems with the system. Most of the catch basins observed were clear of debris and free of standing water and there was no evidence of overtopping or flooding observed. Two catchbasins were noted where potential problems could occur in the future. The existing catch basin shown in photo #1 is located at the northeast corner of the subject site. As shown in the photo the rim of this catchbr.sin is approximately a half-foot lower in elevation than existing grade which could cause deUris to collect and clog the intake grate.l'lie catch basin shown in photo m2 on the west side of Rainier Drive at the intersection of Rainier and Tereve Drive is lower in elevation than the sunounding grade. Red landscape rochs surrounding the catch basin aze falling into the catch basin sump and cou(d eventually clog d�is structure.