9900 19TH AVE SE 2018-01-02 MF Import

�GHA `4C- CIVIL ENGINEERING, LAND PLANNING, SURVEYING. ENVIRONMENTAL SERVICES 42 A October 21, 1997 D Ctydof Everetton e BIdgCITY* Pe7 fV -.. �T....•••., Building Department rmft Come T 3200 Cedar Street Everett, WA 98201 RE: Final Revised Rough Grading and Temporary Erosion Control Plans Everett Home Base Project Our Job No. 5947 Dear Gordon: As discussed during our meeting yesterday with you, Larry Crawford, Jane Zimmerman, and other representatives from the City, developer, and Construction Associates, the project's general contractor, the rough grading and temporary erosion control plans have been revised to incorporate the following comments: We have reviewed with the contractor the proposed method of filling within the wetland area while maintaining appropriate erosion control measures. In an effort to separate and protect the off -site wetlands to the north and reduce the potential for discharge of silt -laden water from the proposed fill area to the outside wetlands, we are proposing a sheet pile wall across the north property line extending a distance of approximately110 feet in length. The wall will be constructed to a height of approximately 3 feet above the existing grade. This wall will also prevent any backwater from the off -site wetlands to the north from flowing onto the site. A 6- foot-wide notch weir will be provided in the sheet pile as an emergency overflow. A dewatering point has also been located on the plan to allow for pumping of the clean water out of the existing wetland area to be filled. An elevation view and cross section of the sheet pile wall and dewatering point have been provided on the plans. 2. The construction sequence has been revised to incorporate the sheet pile construction and dewatering point. 3. The October 17, 1997, letter to Larry Crawford outlining the general sequence of critical construction items has been revised to include the storage volumes being provided or lost during the various construction phases to better demonstrate how the required live storage volumes in the wetland will be maintained during the construction phase. This letter has also been updated io include the construction of the sheet pile wall and dewatering point. 4. A special note has been added to the plans indicating that the temporary erosion control measures shown on the plans are the minimum required to control erosion and help prevent silt- !aden water from discharging off site during the construction phase. Depending on weather conditions and actual field conditions, additional erosion control measures will most likely be required by the contractor. Because of the time of year of construction during wet weather 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 FAX