3301 SEAWAY BLVD WHOLE SITE 2025-10-30

s Sabrina Fandler , City of Everett Public Works Engineering/ Permit Services Division -3- ' f' February 15, 2017 facility, etc.) must be no less than 90-100' (whatever you determine with your engineering expertise and justification). The detention pond will likely need to be reconfigured to be located outside of this critical setback and may require vertical cuts instead of sloped walls in order to achieve this. Response: With the redesign of the pond, there is now a vertical wall instead of sloped pond sides that occur outside the protection area. It is our understanding that the City may allow a reduced setback, provided a slope stability analysis by the geotechnical engineer confirms the pond would not negatively impact any slopes. The geotechnical analysis indicated the new pond configuration with wall would not have any adverse impacts on the slope stability, and this pond configuration would be acceptable. ii. Please see the second attachment for the criteria in the Planned Action Determination (PAD) that haven't been met at this time. Of particular importance for this site is the construction management plan. I briefly reviewed the SWPPP that was included in the drainage report and it isn't adequate to address the conditions in the PAD, particularly with respect to implementing the recommendations in the geotechnical report and the provision of a construction sequencing plan. It also includes an incorrect description of the proposed construction activities in Section 2.2. On this site, the storm water detention pond is proposed to serve as the project's sediment ontrol pond. However, requirement#18 prohibits exfiltration from the pond, �iringIall phases of construction. How and when will the pond be built and, in particular, lined to prevent exfiltration from the pond? How much clearing will be allowed before this critical facility is constructed? Will the site be cleared and graded all at once? How will the slopes of the pond be protected during clearing and grading? These and additional questions must be answered and outlined on the plans for the contractor to follow. Response: The pond will be lined with a flexible membrane liner (FML) Enviro EP 6040 Textured Liner or equal as per the Geotechnical Engineer Recommendation. It will line the entirety of the pond side slopes to prevent exfiltration. A more complete construction sequence referencing more recommendations from the geotechnical c6(1 engineer has been added anti should he sufficient t an warinn t qu.stioos about the construction; ad?0Y) ` 1 - - I 6,Lei 12 / 51.0/1. ,t 1. The TESC Plan likely needs to have additional information or be revised to meet these criteria. It is highly advised that stormwater from the site during construction is collected in other methods such as a baker tank and not routed to the detention pond. Careful construction is required including an impermeable pond liner, so no construction runoff should be routed to it. Response: It is understood that the detention pond needs careful construction however, because the construction will be done carefully and under the close supervision of the geotechnical engineer while following the construction sequence, the use of the permanent pond for TESC purposes should be allowable. I am concerned about the proposed location of the MWS, both from an access and geotechnical standpoint. The GULD for the MWS requires review and approval of the site plan by MWS to ensure that site grading and slope are appropriate for the use of