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� �ME�A 2707 Wetrnore Avenue <br /> Everett, WA 9820'f <br /> ENGINEERING, INC. t 425_387_3820 <br /> f 425_259_'1958 <br /> September 3rd, 2015 <br /> Sabrina Fandler <br /> Engineering/Public Services Department <br /> Public Works <br /> City of Everett <br /> RE: Second Plan Review Comments <br /> Permit Application #: PW1506-024 <br /> Dear Sabrina, <br /> This letter is intended to summarize the changes made to the engineering package reviewed during the <br /> initial permit review for this project. This letter addresses comments from you and other City employees <br /> which were provided in a letter dated August 5th, 2015. <br /> 1. The existing driveway cut is called out to be replaced to meet standard drawing 307. The <br /> revisions as well as the detail can be found on sheet 2 of the revised plans. <br /> 2. A separation of 3 feet from the bottom of the infiltration trench to the seasonal high groundwater <br /> table/hard pan has been provided. Soil logs provided by Geotech Consultants verified no <br /> groundwater was encountered to a depth of 9 to 10 feet below grade. Please see the revised <br /> infiltration trench detail on sheet 2 of the revised plans. <br /> 3. Soils testing has been conducted by a geotechnical engineer per Chapter 9.3.4 of the City's <br /> stormwater manual. Geotech Consultants provided a subsurface infiltration assessment, <br /> including soil logs. A recommended long-term design infiltration rate of no more than 0.25 incher <br /> per hour was assumed, per the geotechnical report. The soil logs provided also indicated that no <br /> groundwater was present at the time of excavation to a depth of 9 to 10 feet below grade. The <br /> infiltration trench was resized based on the information provided in the geotechnical report. It is <br /> recommended by the geotechnical engineer that the infiltration trench extends through the upper <br /> silty soils to insure the bottom of the trench reaches the outwash sand and gravel layer. Please <br /> see the revised infiltration trench detail and plan view on sheet 2 of the revised plans. See the <br /> revisions on page 9 of the drainage report. <br /> 4. See page 10 and 11 of the revised drainage report. The infiltration trench has been resized to <br /> comply with the applicable flow control standards. Using W1NHM12 to analyze the change in <br /> peak flow rates for the existing and developed conditions, the flow durations calculated had all <br /> "passes". <br /> 5. All comments/markups on the plans and drainage report have been addressed. Please see the <br /> revised plans and drainage report. <br /> Thank you for taking the time to review the revised plans for this project. Please feel free to contact me <br /> with any questions you may have. <br /> Sincerely, <br /> �G�,o�s� �a��— <br /> Rachel A. Jacobs, E.I.T. <br /> Omega Engineering, Inc. <br />