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The Big Green Sponge
This document summarizes impervious surface area and green infrastructure opportunities in the City of Lancaster. It finds that roads make up 25% of impervious area, buildings 41%, and parking lots 32%. It then outlines potential green infrastructure projects for parking lots, alleys, parks, and schools that could capture over 1 million gallons of annual runoff. Finally, it estimates that targeting 50-85% of impervious area from various sources could reduce runoff through practices like green streets, porous pavement, tree planting, and ordinances.
The Big Green Sponge
- 3. IMPERVIOUS AREA INCITY OF LANCASTER Roadway Railroad 25% Building 2% 41% Parking Lot 32%
- 4. IT’S BEEN FUN,BUT NOW… Figuring out scale Institutionalizing -ordinance -sustainable funding
- 6. EXAMPLE DEMONSTRATION PROJECTPOROUS PAVEMENT PLAY COURT: 6TH WARD PARK
- 7. 6TH WARD PARKUNIT COST COMPARISON
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- 11. TOTAL Parking Lot Drainage GI Area Capture Capital Area Volume Costs with Contingenc y Plum Street 23,402 4,680 511,000 $89,862 Dauphin 20,582 4,516 411,000 $61,822 Penn 22,758 4,219 455,000 $60,749 Mifflin 13,242 1,324 265,000 $27,013 TOTAL 1,642,000 $239,446 COST PER GALLON = $0.14/gallon
- 12. GREEN STREETS &ALLEYS
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- 16. HOW MUCH WENEED TO MANAGE? Assumed Assumed Impervious Total WQv or Average Percent of Runoff Green Infrastructure Project / Area SW BMP Annual Area / Impervious Source Impervious Reduction Program Type Managed Runoff Capture Runoff Area (MG/yr) (acres) (MG/yr) Volume Reduction Managed (in.) Roads / Alleys Green Streets 30% 158.7 513 1.0 86% 132.4 Parks Park Improvements / Greening 85% 17.0 19 1.0 86% 14.2 Sidewalks Disconnection, Porous Pavement 35% 43.3 120 1.0 86% 36.1 Parking Lots Porous Pavement, Bioretention 20% 129.5 628 2.0 97% 121.3 Flat Roofs Vegetated Roofs 15% 32.7 212 1.0 86% 27.3 Sloping Roofs Disconnection/Rain Gardens 25% 163.5 635 1.0 86% 136.5 Street Trees Enhanced Tree Planting N/A 45.1 44 0.3 49% 21.5 Public Schools Green Schools 75% 38.4 50 1.0 86% 32.0 Various (Ordinance) First-Flush Ordinance 50% 637.0 1236 1.0 86% 531.6 Total 1,265 3,752 1,053 55%
- 17. PUT ANOTHER WAY… Area/Impervious Assumed Percent Source of Impervious Area Managed Roads/Alleys 30% 468 Blocks Parks 85% 26 Parks Sidewalks 35% 89 Miles Parking Lots 20% 287 Parking Lots Flat roofs 15% 246 Roofs Sloping Roofs 25% 2,195 Buildings Street Trees N/A 56,700 Trees Public Schools 75% 15 Schools Various (ordinances) 50% 2,536 non-residence parcels
- 18. PARCEL VS. IMPERVIOUSAREA Parcels Impervious Area Residential Residential Multi-Family Multi-Family Non-Residential Non-Residential 14% 20% 11% 4% 75% 76%
- 19. OUR THANKS… National Fishand Wildlife Foundation Keith Campbell Foundation for the Environment PA Department of Environmental Protection PA Department of Conservation and Natural Resources Lancaster County Planning Commission Chesapeake Bay Commission PENNVEST And many individual donors…