Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

Runoff Treatment Control Measure Fact SheetInfiltration TrenchTable IT-2. Inspection and Maintenance Recommendations for Infiltration TrenchesActivityMonitor the infiltration rate in the trench during and after storms byrecording the drop in water depth versus time using a calibrated rodor staff gauge.Clean the trench when the infiltration rate decreases significantlyover the design rate. To clean it, remove the top layer of gravel andclogged filter fabric, install a new layer of filter fabric, wash theremoved gravel, and place the washed gravel back into the trench.This maintenance activity is expensive and can be avoided bypreventing upstream erosion and maintaining the pretreatmentbuffer strip.Inspect grass buffer strip to identify potential channelization anderosion problems.If channels are forming or erosion is occurring within the grassbuffer strip, add soil as needed and stabilize with erosion controlmulch or mat and re-seed or re-vegetate immediately. See theVegetated Filter Strip fact sheet elsewhere in this chapter for moreinformation.Inspect trench to identify potential problems such as standing water,trash and debris, and sediment accumulation.Remove pioneer trees that sprout in the trench vicinity so that rootsdon’t puncture the filter fabric, allowing sediment to enter the trench.Trim adjacent trees so the canopy doesn’t extend over the trenchsurface.Remove litter and debris from trench area.Reconstruct or replace the control measure when it is no longerfunctioning properly.ScheduleSeveral times during first year thennear the beginning and end of eachwet season. Additional monitoringafter periods of heavy runoff isdesirable.As requiredAt beginning and end of the wetseason. Additional inspections afterperiods of heavy runoff aredesirable.As neededAt beginning and end of the wetseason. Additional inspections afterperiods of heavy runoff aredesirable.As neededAs neededAs neededSee projected lifespan inAppendix B for informationalpurposes.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007IT-5