5805 HIGHWAY PL 2019-03-18 - Laserfiche WebLink

VII. Other Permits: Only City of Everett permits are required for this project VIII. Permanent Stormwater Control Plan A. Off-site Analysis The downstream drainage system for the subject site was investigated for approximately 0..25 mile on 7/25/2015.Weather conditions the weeks prior to the investigation consisted of sunny worm days with no rainfall.The day of the investigation was a cloudy rainy day with heavy rain at times.The extent of the drainage system investigated consists entirely of underground conveyance system. Observations of this system are therefore limited to evidence of overtopping or flooding and/or silted or clogged structures. The downstream conveyance system generally runs north along Highway Place. The system is within the 36 Street combined sewer system.At the time of the 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.There was no evidence of overtopping or flooding observed. There were no unusual conditions within the quarter mile investigation. Included is an exhibit(Appendix A),provided by the City of Everett, showing the conveyance system route. B. Pre-Developed Hydrology See Appendix B C. Developed Hydrology See Appendix B D. Stormwater Flow Control Plan Runoff control facilities will consist of underground detention tank designed to detain runoff from the developed site and release the runoff volume based on the City of Everett's method for a combined sewer outside downtown.The detention tanks are designed to accommodate the stormwater runoff from the entire site,including the parking lot and roof tops.Detention volume will be provided by using one 3.0-foct diameter underground detention tank. The tank is 40-feet long.The detention facility will discharge into the existing storm drain system located in the gutter line of Highway Place at the northwest corner of the site. For Drainage Calculation See Appendix B.