2121 W CASINO RD AEROSPACE MACHINIST UNION 2018-01-01 MF Import

1 6615 MOWAAD NtSOL■� TAMM<N 0 �■RORNDOFF INC. P.S. January 13, 1981 ""I Mr. Richard F. Johnson, P.E. Hydraulics 6 Water Quality Enqineer District No. 1 Washirqton State Dept. of Transportation 73Q0 perireter Road South Seattle. WA 9A108 Re: Aero Machinists Office Duilding Everett, WA Dear Mr. Johnson: As we discussed by phone this date, HNTB is servinq as the Design Engineer for the above referenced pro,iect. Accordingly we have developed the enclosed site plan. A vicinity map is attached for your reference. There is an existing wet weather steam located on the west pr•o- perty line of the pro,iect site which drains north across SR526 in a 48 inch culvert. As indicated by the site olan, the pro- posed drainage improvements consist of an on-site detention sys- tem (in pipes) and the installation of a 48-inch pipe to replace the open stream. This 48-inch pipe serves only to pass the off- � site drainage which previously went through the project site. The proposed headwall will be placed south of the SR526 right- of-way and the outfall area will be riprapped. There is essen- tially no slope on the proposed 48-inch pipe due to the existing upstream and downstreat invert elevations. Discharqe velocities arz anticipated to be approximately 2.5fps for a 19 year storn. 41e understand that a permit is not required as long as there is no work on State right-of-wa.y. The plans are therefore, submitted for your information. If you have any questfons, please give me a call. Very truly yours, HOWARD NEEDLES TAMMEN 6 DERGENOOFF INC. P.S. �X��l �1��'yC�ti. �Jack Carman, P.E � JEC:smb Enclasure (� _� cc: City of Everett, Lon Mayberry � � � � � U 15 D ul� prcryrye�y and plwten 600 tOB�h Avenue. N.E. Suite 405. Bellewe,WA 98004 ��s-�,s�s1981 ` �. O . � . CITY OF EVERETT � .. ,,,_ ,.�_.�.. �-.,' , .