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Home My WebLink AboutBLD93-0236 Stormwater Plan - BLD Engineering / Geo-tech Reports - 4/12/1994 00 �L41 Phone 427-9670 Ext 450 ,/ Jerry W Hauth,PE.PLii Area Code (206) v Iy Z Director S V DEPARTMENT OF PUBLIC WORKS ON COURTHOUSE BLDG 1, 411 NORTH 5TH STREET TP.O. BOX 1850 SHELTON,WASHINGTON 98584 April 12, 1994 Ken Tame 21303 NE 17rh Court Redmond, WA 98053 Re: Saint Hugh Episcopal Cliurch Stormwater Plan Ken, The Mason County Public Works review of the proposed stormwater plan and supporting calculations for the Saint Hugh Episcopal Church in Allyn, is Mete and except for some minor concerns, the proposal appears to provide adequate stormwater detention and treatment to mitigate the environmental impact of the facility on the si?Y2"ounding community. The concerns which are still a problem both concern the detention pond and discharge structure. In particular, the width of the top of the downslope side of the berm creating the detention pond is not detailed in the proposal submitted by Mr. Week. I have discus.:-�d this with him and pointed out that at the discharge pipe location, it appears that the pond's dike or berm slopes up to an elevation of 16' from the inside, and then must drop down to an elevation below 10' in a relatively short distance. My personal memory of the site is that the ground on this side of the site slopes away towards Wheelwright street. If a berm is necessary to achieve an elevation of 161 , it will be required to have a minimum top width of 6 feet. This may also require a greater length of discharge pipe than the 38' shown on the plans. Another concern is about the susceptibility of the discharge orifices to floating debris in the detention pond. A trash barrier or wire meshing surrounding the discharge orifices might be appropriate. Some form of protection for the orifice entrances should be provided. The last concern is control of the detention pond elevations during construction. A planimeter check of the pond dimensions reveals to me that there is not a great mein of error available in the pond dimensions. I consider it impracticable to attempt to build the detention pond exactly as drawn. Instead, I feel an as built of the pond should be provided the County once its construction is completed with detailed enough cross section information to determine the finished pond's capacity. If the finished pond dimensions deviate appreciably from the proposal, recalculation of the orifice sizes and locations may be. necessary. Sincerely, k"^ :k�I"" AIAN A. A P/W Office Tech. cc: DCD-Grace Miller, Michael Wnek DECLARATION OF COVENANTS ASSOCIATED WITH PRIVATELY MAINTAINED STORM DRAINAGE FACILITIES Declaration of Covenant In consideration of approval of the development known as , relating to real property legally described as follows: The undersigned, as owner s covenant and agree that: g ( ) , g 1. If at any time Mason County reasonably determines that maintenance or repair work is required to be done to the existing, approved storm drainage facilities installed on the property described above and located outside of any public right-of-way (which will mean repair and or clean out of the existing system only to the same standards as originally installed and approved) , the Director of the Department of Public Works shall give the current owners seven days notice that the County intends to perform such maintenance or repairs, or to have them performed by others. If the current owners have not completed or are not diligently pursuing the repair or maintenance of the system and it becomes necessary for Mason County to perform the work, the current owners will assume responsibility for the cost of such maintenance or repair and will reimburse the County within thirty days of receipt of the invoice. Overdue payments will require payment of interest at the current legal rate for liquidated judgments, and any costs or fees incurred by the County, should any legal action be required to collect such payments, will be borne by the parties responsible for said reimbursements. 2 . If at any time Mason County reasonably determines that the existing and approved storm drainage system on the property poses a hazard to life and limb, or endangers property, or adversely affects the safety and operations of a public way, due to failure, damage or non-maintenance of the existing on-site storm system, and that the situation is so adverse as to preclude written notice to said owners, the Director of the Department of Public Works may take the measures necessary to eliminate the hazardous situation (which will mean repair or clean out of the existing system only to the same standards as originally installed and approved) provided the Director has first made a reasonable effort to locate said owner before acting. The current owners will assume responsibility for the cost of such maintenance or repair; and will reimburse the County within thirty days of receipt of the invoice. Overdue payments will File: H:\WP\STRMWTR\O&M-AGRE.MNT Page 1 of 2 require payment of interest at the current legal rate for liquidated judgments, and any costs or fees incurred by the County, should any be borne by the parties responsible for said reimbursements. 3 . The owner shall keep the Mason County Public Works Department informed at all times as to the name, address and telephone number of the contact person responsible for the performance of maintenance or repair work to the storm drainage facilities. These covenants are intended to protect the value and desirability of the real property described above, and to benefit all the citizens of Mason County. They shall run with the land and be binding on all parties having or acquiring from the current owners or their successors, any right, title or interest therein, and to the benefit of all the citizens of Mason County. Owner Owner STATE OF WASHINGTON, ss. (INDIVIDUAL ACKNOWLEDGEMENT) County of MASON I, ,Notary Public in and for the State of Washington, residing at ,do hereby certify that on this day of , 19 ,personally appeared before me to me known to be the individual described in and who executed the within instrument and acknowledged that signed and sealed the same as free and voluntary act and deed for the uses and purposes herein mentioned. GIVEN UNDER MY HAND AND OFFICIAL SEAL this day of 19 Notary Public in and for the State of Washington, residing at in said County. 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Go�a►rrbvr - 5Q4- '= ��O�u�hiG 7GZ,74 TABLE 1 STORAGE REQUIREMENTS FOR MULTIPLE ORIFICES Type* an 0- ear Design storm 2 - ear Design Storm AREA Number of Peak Storage Maximum Storage Peak Storage Maximum Storage Outlets Time(Minutes) Volume (Cu.Ft/Ac) Time(Minutes) Volume (Cu.Ft/Ac) Seattle/ One T = -25+ 1762 Vs = 2820T - 40QoT T = -25+ 2138 Vs = 3420T - 40QoT Renton No- T+ , �o T+25 Seattle/ Two T = -25+ 10500 Vs = 282OT-29.9QoT T = -25+ 85500 Vs = 3420T-29.9QoT Renton 29 o T+25 K-goo T+25 Seattle/ Three T = -25+ 10500 Vs = 2820T-26.4QoT T = -25+ 85500 Vs = 3420T-26.4QoT Renton 26.4Qo 'T+25 26.4Qo T+25 Seattle/ Four T = -25+ 10500 Vs = 282OT-25.1QoT T = -25+f-22 500 Vs = 3420T-25.1QoT Renton 2�TQo T+25 5 Qo T+25 Seattle/ Five T = -25+ 70500 Vs = 282OT-24.1QoT T = -25+ 85500 Vs = 3420T-24.1QoT Renton ��TQ0 T+2-5-- N.Too T+25 * Orifices with equal head pressure between adjacent orifices. 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