6003 23RD DR W 2018-01-01 MF Import

� Size and Cost Estimate l iVortechs0 Sizing: The Vortechs� unit for this site was sized based on the Department of Ecology's approval with an operating I rate of no more than 35 gpm/ftZ of swirl chamber. Using the water quality flow rate that was calculated above, the minimum swirl chamber needed is 1.92 ftZ. The smallest Vortechs0 unit, the Modei 1000 has a swirl chamber area of 7.0 ftZ, therefore it is the correct unit for this site. I The estimated price for the Vortechs� Model 100Q is $13.300. This price includes the Vortechs System, the system manhole frames and covers and delivery to the site. The price doas not inclucle instailation, additional bypass structures, nor risers, if necessary, to bring the rims to finished grade. The price may be higher if the I system has deep cover (typically deep means more that 5'-0" of fill). The price may also be higher if the ground water table in the area of the System is within a couple feet of finished grade and we need to put an anti- flotation collar on the System to combat buoyancy. We can check these issues once the S,ystem is oriented on J the plans and we have the final rim and invert elevations as well as the ground water elevation. I One item to keep in mind as you place the systems on your site plan is that the unit requires an inlet that is � tangential to the grit chamber - meaning that the inlet pipe must enter the Vortechs System at a corner and perpenc'icular to the side of the system. The outlet pipe can exit at an angle if necessary, but we prefer that this angle be less than 30 degrees off the perpendicular in order to minimize the size of the needed knockout. I Iwould very much appreciate a copy of the final site plan when available. I Basin B: StormFilte:0 Sizing: The StormFilter is a flow-based system, ane+ therefore, is sized by calculating the peak water quality flow rate I associated with the design storm. However, when the StormFilter is piaced downstream of detention the flow rate generated at the water quality storm is not always representative of the total volume of water that will go through the system or type of pollutant-loading the system may experience in one year. f For Basin B, CONTECH Stormwater Solutions Inc. recemmends using a 48" Manhole StormFilter with 2caRridges (sez attached detail). The estimated cost of this system is 14 300, compiete and delivered to the job site. This � estimate assumes that the vault is 5 feet deep. The final system cost will depend on the actual depth of the unit and whether extras are specified. The contractor is responsible for setting the StormFilter and all external plumbing. � The 48" Manhole StormFilter has an internal bypass capacity of 1.0 cfs. If the peak discharge off the site is expected to exceed this rate, �e recommend placing a high-flow bypess upstream of the StormFilter system. CONTECH Stormwater Solutions could provide our high-flow bypass, the StormGate, which provides a combination weir-orifice control structure to limit the flow to the StormFilter. The estimated cost of this structure is $4,000. The final cost � would depend on the actual depth and size of the unit. I I � I I C�2006 CONTECH Stormwater Solutions 12021•B NE Airport Way,Portland OR 9i220 Page 2 of 2 contechslor^�wa�er.com Toll-free:800.548.4667 Fax:800.561.1271 TS•P027