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Ramsey Conservation District 1425 Paul hirAwold Dr. Arden Hill, MN 55112 Teiephaae 651 / 266 -7270 Fax 651 / 266 -7276 op wwwdMMWYMDSC ation.org TO: Grass Lake Water Management Organization Board Members Tom Petersen, Grass Lake Water Management Organization FROM: Ryan Johnson, Ramsey Conservation District DATE: 19- Sep -I 1 RE: Stanley Cost Share Application/Contract BACKGROUND: Ms. Eileen Stanley contacted the Ramsey Conservation District (RCD) in July 2011 about redoing her driveway in a way that would help reduce stormwater and help the water quality within Grass Lake Water Management Organization (GLWMO). She wanted to know more information about porous materials and if it is an eligible practice for cost share. Within Ramsey County, the other watershed districts and water management organizations cost share on porous driveways because of the volume reduction benefit. Typically the cost share is based on two bids: I bid that is for an entire driveway with typical materials and the other bid is with a porous material, or section of porous. The difference between the 2 bids is what is eligible for cost share. In this case, there is a $2,500 difference between the typical concrete driveway and the typical concrete driveway with a porous section. The potential cost share would be $1,000, based on the raingarden (infiltration) standard in GLWMO. The typical project maintenance term for cost share projects in GLWMO is 5 years. In other districts, there is a 10 year term for structural projects, including porous driveways. The maintenance would include monitoring the porous material for functionality after installation, and keeping the top course clear of sediment by vacuuming, or other means necessary, to help the long term operation of the infiltration practice. RECOMMENDATION: It is my recommendation that the project be awarded the cost share funding of $1,000.00 or 509/6 of the eligible project cost, whichever is less. I would also recommend that the cost share term for maintenance be 10 years, versus the standard 5 years. This will allow for a reduced cost per pound removal of volume and total phosphorus over the maintenance life of the project. The project will be a great example of a small porous driveway project. The porous driveway section will capture a 0.75' volume of water from the contributing watershed and will capture and treat a 1. C' Type B Rainfall (Type 11 Rainfall: 24 hours in duration and the storm intensity is in a shape of a bell curve).. This volume of water will now be disconnected from the street which ultimately runs to Bennett Lake and Lake Owasso. Sincerely, Ryan Johnson