222 W MARINE VIEW DR 2016-01-01 MF Import

r�' 7 h�tli" � i ( �:�: December 28, 1994 File No. 24-92-009-007-01 Paul McKey City of Everett Public Works Depazhnent 3200 Cedar Street Everett, WA 98201 Subject: Sterling Asphalt Batch Plant Dear Paul, Enginttn planntn Surntyort Reid Middleton 1903133rd Are. W. Suite 301 P.O. Box 6638 t�„�,w�a, w� 98036-0638 rna�� xoc ns-�� r�,x �os ns�39 The revised drawings for the storm system at the Sterling Asphalt Batch Plant facility aze enclosed. As discussed eazlier, these drawings reflect a change from the concrete wet vault to a more cost-effective corrugated metal pipe vault to obtain storm water quality treatment in accordance with the intent of the city ordinances. The design vazies somewhat from the calculadons presented earlier to you and Jane Zinunennan. The vault has been converted to a single lon;; tube rather than two pazallel tubes. The original configuration caused structural loading probl,:m: on the wet pond retaining wall. Revision commenu to the original calculations aze attarhed showing the effects to the original calculations. The design includes sealing the bottom of the vault to ersure that 3 feet minimum dead storage is always maintained in the vault Although we do not znticipate any significant leakage from the standazd installation, the manufacturer's available documentation on maximum leakage rates would not guarantee 3 feet of dead storage at all dmes of the yeaz. Catalog information on the proposed sealants is included for your informadon. Our project geotechnical engineer has looked at the possibiliry of fines migraang from the surrounding soil if the vault ever does leak. A copy of their letter is enclosed, wh�ch basically concludes the gradation of the exisring soils at this particulaz site aze low enough that fines migration is not a concem. We hope this information meeu your requiremenu, and you can approve the proposed changes. ff you have any additional questions, don't hesitate to call me. Sincerely, REID MIDDLETON, INC. �� Robert O. Galteland, P.E. Project Engineer vlf�wt�sterling�rnckeyltr.rog Enclosures cc: Sterling Asphalt Baugh Industrial Construction o r��od� p �pN O 11995 . w . ................. ............................ ........ C�, �p�rtEt CouMer