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Convenlional control of a detention reservoir's release rale relic-, on an <br /> orifice plate, weir, or gale. As the storage level in the detention reservoir <br /> decreases,the hydraulic head on the outlet works also decreases,resulting in <br /> a decrease in the release rate from the reservoir.This means greater storage <br /> Ir--L oo-- C�(,,1 , volume is required to detain runoff from a storm than would be required if <br /> discharge front file reservoir was maintained at the design release rate at all <br /> storage levels. I he idea of a constant release tate is the key to McCarthy's <br /> development. <br /> Fl <br /> is <br /> 'I he microcontroller system allows the design release tato to be maintained <br /> out w. , Coi-istrol <br /> SENSOR MEASURES WATER <br /> LEVEL. AND lNrLOW RATE <br /> MICROCONTROLLER INTERPRETS <br /> t0% Better Stux-hrmw-ste -e SIGNAL FROM SENSOR AND <br /> CONTROLS MOTOR <br /> ELECTRIC MOTOR ADJUSTS <br /> Mnam gvu m e n t FLOW RESTRICTOR <br /> To Downstream From St�trrtsater <br /> Sy <br /> alem Reservoir <br /> of irritation to nrrhy developers and a significant source of FLOW RESTRICTOR REGULATES <br /> pollution,storntwater has become a greater concern to many municipalities. STORMWATER OUTFLOW RATE <br /> State and local agencies throughout the country have Increased tnininttrrn / AND DETENTION.TIME <br /> requirements for storrnwater management in new developments as a result. ✓ <br /> One water resource engineer believes he might have a solution. The microcontroller system allow'precise control 04 stormwater flow. <br /> Ed McCarthy, Ph.D., P.E., of GcoDintcnsions, a Kirkland, Wasl►.-based <br /> engineering firm, is dc%cloping a decision-based slotnnwater contiol system cor all storage levels in the reservoir. 'f he system accomplishes this by <br /> _. ._ adjusting the resitictor flow area to compensate for changes in hydraulic head. <br /> "(Conventional detention ponds are] designed at a release rale when the <br /> reservoir is fern,"he explains."When the level decreases,the pressure head on <br /> j 0 the orifice decreases so the flow rale from the pond decreases.With this new <br /> control system,you woultl maintain a constant flow for all stage levels." <br /> ILL ' <br /> By making better use of the reservoir volume, less volume is required to <br /> OOwfrSrRrAN s TEM ` _ �f handle the sante storm,he notes. Flecause the system would make better use <br /> F[r,El�fS nr$fnARGE yJ /„ . <br /> rn xI ccvnra SmuCIU I I P (�'„�, lir :,yn �� of detention reservoir storage volume,existing undersized detention ponds <br /> corr rctx sTarIc ru Rr I .l could be retrofitted to perform more effectively; new detention ponds dc- <br /> RF,UtATES ME REIEASE <br /> RATE FROM WE VVENRON 5IrnMWAIf?IS COEitCI,n signed with file microcontroller system would occupy a smaller amount of <br /> r �RESFRVTYR RI CA 101 RABBIS <br /> -� \ 1, valuable real estate. <br /> 1, `StrVWWA1rR r$CONKKO ht additiolt to reducingvolume requirements, the system can be ro- <br /> 'L IO nK OE RN110H PESERMIR q + Y p <br /> -VE""M RESERVOIR granuned to convert stormwalcr detention ponds into irrigation sources and <br /> PRO�"S SEORACF <br /> FM SIO'RA/WARIP can control the hydrology of created wetlands,says McCarthy. <br /> Stormwater collected in developed areas Is conveyed to a detention pond The microcontroller system, which utilizes off the-shelf technology in <br /> before being released at a controlled rate to the downstream system. combination with sophisticated softwate, awaits further development. <br /> McCarthy hopes that,with additional funding and testing,the first commer- <br /> thal promises to provide improved nnanagentenl of'siorrnwaler collected livor cial applications could come as soon as next year. <br /> developed sites. 'Che systctn, which utilizes a microcontroller to regulate I Ie estimates the installation cost for a system in a typical 50-acre residen- <br /> discharge from detention ponds, would make better use of reservoir storage tial development with 60 to 100 lots would be$10,0(0 to S15,0t0. <br /> volume. For many sites, claims McCarthy, the flow control system would <br /> reduce storntwater storage volume requirements by up to 40 percent. <br />