6611 ASSOCIATED BLVD BASE FILE 2016-01-01 MF Import

I ! Design and Operation Basic Operation The Vortechs� System is a hydrodynamic separator designed te enhance gravitational separation o( floating and settling materials from stormwater Oows. Stormwater flows enter the unit tangenlially to the grit chamber,which promotes a gentle swirling motion.As polluted wzter circles within Ihe gnt chamber,pollutanls migrete toward fhe center of the cnit w!�ere veiocities are the lowest. The majority ot seltleable solids are le(t behind as stormwater exits ihe grit chamher lhrough two apertures on the Ipenmeter of the chambec Next, buoy ant debris and oil and grease are separeted :rom water flowing under the ba(fle wall due to their relatively low specific gravity. As srormwater exits�tie System through the (low control wall and ultimalely through the outlet pipe, il is relalively(ree o(Ooat�g and settling i pollutants. Over time a conical pile tends to accumulate in the center o(h e unit containing sedimenl and associated metals, nutnents, hydrocarbor.s and other pollutants. Floating debns and oil and grease � (orm a floating layer trapped in front of the baffle wall. Ac:;umulation of these pollutanls can easily be i accessed through manholes over each r.hamber. Maintr.nauce is typically periormed through the manhole over lhe grit chamber. i Design Process Each Vorte�hs System is custom designed based on: • Site size • Sile runoff coefficient i • Regional preci�itation intensiry distribution • Anticipated pollutant ch,�ractenstics These factors are incorporeted into the Ralional Rainfall MethodT'" to estimate net annual pollutant removal effciency. The Ratlonal Rainfall MethodT" � DiKerences in local climale, topography and scale make every site hydraulically unique. it is important to take these factors into consideralion when estimating the long-lerm per(ortnance of any stortnwater ireatment system. The Rational Rainfall Methodi° combines site-specifc information with laboratory generated performance data, and local histoncal �recipitalion records to esti!nate efficiencies as accurately as possible. Short duration rain gauge records from across the Uniled States and Canada were analyzed to � determine lhe percent of lhe tolal annu2l reinfall that fell at a range of intensities. US stations'depths were totaled every 15 minutes or hourly and recorded in 0.01-inch increments. Depths were recorded hourly with 1 mm resolution al Canadian stations. One Irend was consislenl al all sites; the vast � majoriry of precipitation fell al low intensities and high intensity storms contnbuled relatively little to the . total annual depth. These inlensities, along with the total drainage area and runoff coefficient for each specifc site, are lranslated inlo (Iow retes using tne Rational Rain(all Method. Since most sites are relatively small and highly impervious,the Rational Rainfall Method is appropnate. Based on the flow rates calculaled for each intensity, an opereting rate within a proposed Vortechs System is determined. Finally,a removal efficiency is selected for each operating rate based on anticipated pollutant charactenstia and on full iscale laboretory tests. The relative removal eKciency at each operating rete is added to produce a net annual polWlant removal effciency estimate. CONTECH Stormwater Solutions rypically selects the system that will provide an 80°'o annual TSS 1 load reduclion based on laboratory generaled performance curves for 50-micron sediment particles, i 1 t d OO 2006 CONTECH Stormwater Solutions