Slide 1

Feasibility of Infiltration and Harvesting/ReuseAnalysis and Documentation for Stormwater Control Plans

1Infiltration Criteria

OverflowUnderdrain4%12"20%80%250,000 hrsWhat is the minimum KSAT?2

3TreatmentInfiltration/ EvapotranspirationHarvesting /ReuseBiotreatment(Bioretention)High-Rate BiofilterVault-Based Filter

4Screening for Adequate DemandIdentify and list sub-areas of site from which runoff could feasibly be capturedCalculate demand for toilet flushingCompare demand to drawdown required to use 80% of average annual runoff.Toilet flushingLandscape IrrigationOther uses

5Required Demand Reuse (80% of total)

50,000 gallonsstorage(for example, about25' diameter x 14' high)

30+ years of hourly runoff from one acre Overflow(20% of total)Table 4-3 on page 41Rain GaugeMin. Demand(gal/day/acre)Berkeley5900Brentwood4200Martinez5900Dublin41006Select Roofs or other SurfacesList specific impervious areas from which runoff might be feasibly captured or stored.All contiguousroof areas 10,000 SF andgreater mustbe listed.

Page407Default Toilet Flushing UseLand Use TypeUser UnitUser Unit Factor (Optionaluse project-specific data if available)Daily Use/Unit (gal./day/user unit)*ResidentialResident2.8 residents/ dwelling unit8.6Office or RetailEmployee (non-visitor)200 SF/employee6.9SchoolsEmployee (does not include students)50 SF/employee33.9Industrial Uses (not including process water)Employee (non-visitor)5.4*Or use project-specific data8Mixed Use DevelopmentABCDEFGHIJAreaSFAcresUses and User UnitsToilet and Urinal Usage(gal/day)Water Use per AcreReqd Demand per AcreF>G?Adjacentpervious area 2.5 B?Other Use G?B-1210000.4877 DUs + 9000 SF Retail1854+ 310= 2164 45085900NoNoNo77 DUs 2.8 residents/DU 8.6 gal/day/resident = 1854 gal/day

9000 SF retail 200 SF/employee 6.9 gal/day/employee = 310 gal/day Page419ABCDEFGHIJAreaSFAcresUses and User UnitsToilet and Urinal Usage(gal/day)Water Use per AcreReqd Demand per AcreF>G?Adjacentpervious area 2.5 B?Other Use G?All411020.9423DUs5545895900NoNoNoBldgs189750.4423DUs55412715900NoNoNoBldg A41250.0923DUs55458505900NoNoNo

23 DUs x 2.8 residents/DU x 8.6 gal/day/resident = 553.8 gal/day

554 gal/day .94 acres = 589 gal/day/acre10Harvesting and Use ConundrumLarger tributary area and lower useFrequent overflow during wet periodsBest for water conservationSmall tributary area and high useUses a larger proportion of water collectedBest for disposalNot cost-efficient11

Harvesting with Bioretention12Regulatory StatusMRP Adopted October 2009Submittal May 1, 2011Implementation to October 2014Report on Reuse Implementation due December 1, 2013Discussion of criteria employedBarriers to implementation and strategies for overcoming barriersProposed changes to criteria and rationaleUpdated guidance13