Houston Land/Water Sustainability Forum David W. Peters, P.E., CFM, D.WRE February 6, 2008

Summary The Private – Public – Private Responsibility Shift EPA Case Studies Local Church Revision to LID Final Notes

The Private – Public – Private Responsibility Shift Agricultural Beginnings – prior to 1940 Farmers Objective – Capture and retain as much moisture as possible

The Private – Public – Private Responsibility Shift Subdivisions developed rapidly form 1950 through 1985 Homeowners Objective – Drain and remove rainfall as quickly as possible

The Private – Public – Private Responsibility Shift Through the decades the responsibility for the rain has shifted from the private land owner to the public agencies (City, County, Flood Control) Economic Question to ponder is which is less costly: Private Owner handling the raindrop where it falls Private Owner passing the raindrop to Public Entity to handle

EPA Case Studies The EPA presented 17 case studies in a report titled “Reducing Costs through Low Impact Development (LID) Strategies and Practices” Report is available online at: Primary LID Techniques are: Bioretention Grassed Swales Reduced Impervious Area Cluster Building

EPA Case Studies Auburn Hills Subdivision, Wisconsin Overall Savings 32% 56% of savings was in storm water management using bioswales and vegetated swales Development used cluster development with 40 percent open space Savings reduction were also realized in water and sewer installation and are not including in the 32% LID savings

EPA Case Studies Mill Creek Subdivision, Illinois 1,500 acre mixed use community with overall savings of 30%. Savings was $3,500 per lot. 70% of savings was in storm water management using vegetated swales Development used cluster development with 40 percent open space In addition to savings on development, the lots near amenities with view of open space and bike trails were sold at $3,000 to $17,000 premiums

EPA Case Studies Somerset Subdivision, Maryland 80 acre residential community with 200 homes on 0.25 acre lots. Overall savings of 32%. Savings was $4,000 per lot. Half of subdivision was conventional and half was LID Each 10,000 sq. ft. lot had a 400 sq. ft. bioretention cell. LID runoff was 20 percent less and metals showed an average of 30 percent reduction

Local Church Revision to LID Church construction required a 10 ac-ft detention pond to meet County standards. Pond location at rear of property required piping to rear and then back to discharge at front. Shallow outfall required shallow pond or pumped discharge

Local Church Revision to LID LID Options Considered Add grass strip filter to parking areas and allow parking areas to flood to 6 inches during extreme events (> 10 year recurrence) Convert grassed areas near front and side of church to depressed rain gardens Flooding of parking lot and rain gardens controlled by regulated outlet at discharge from property

Church Site Layout

Final Notes Project overall objectives need to be examined when LID options are considered Economic benefits may not only be in initial construction cost savings, but increased values of LID developed properties The closer to the source that storm water can be mitigated the lower the transmission costs will be Creativity and flexibility needs to be applied to each project based on final objectives Shifting storm water maintenance to the private homeowner may be problematic unless legally encumbered into the property deed requirements