Nobis Engineering, March 18 2015 STORMWATER BMPs: Selection and Applications Images: Grand Rapids Community Media Center
Basic BMP Functions Treatment Infiltration Detention Conveyance Images: H20 Resources
Conveyance & Detention Images: Wikipedia
Treatment & Infiltration Image: CT NEMO
Low-Impact Development Minimize impervious areas, maximize greenspace Multiple small BMPs, not massive structures Treat & infiltrate runoff at source Image: SVR Design
What BMP Should You Use? Stormwater requirements Impervious Surfaces Pollutant Loads Groundwater Recharge Image: kennethquillian.com
What BMP Should You Use? Site Limitations Small/Narrow areas Unsuitable soils/high groundwater Proximity to critical areas/tmdls Maintenance concerns $$$ BUDGET $$$
What BMP Should You Use? Retrofitting Images: City of Portland Oregon
Stormwater Handbook BMPs Available on MassDEP website http://www.mass.gov/eea/agencies/massdep/water/regulations/massachusetts-stormwater-handbook.html (or you could just google it) Voume 2, Chapter 2: Specifications & Guidance for BMPs 10 Stormwater Standards BMPs help to meet Standards 1-7
Stormwater Handbook BMPs Pretreatment Treatment Conveyance Infiltration Other BMPs
Pretreatment BMPs Image: US Fish & Wildlife
Deep-Sump Catch Basins A normal catch basin - with sump to capture sediment Requires regular cleaning Images: SeaGrant, MBO Precast
Sediment Forebay Preliminary treatment Settling basin Stone or concrete Images: University of Idaho, Solitude Lake Management
Vegetated Filter Strip Parking Lots Roadways Images: Vermont DEC, Green Infrastructure Digest
Oil/Grit Separators Large multi-chamber vaults Compact drain manhole footprint Images: FHWA, Konkast
Catch Basin Inserts Use existing CB s Cleaning requirements Images: Stormwater Buffer Zone. Oldcastle FloGard
Treatment BMPs Images: Wikipedia
Bioretention Areas / Rain Gardens Combines soil, plant, and microbes to treat stormwater Very high (up to 90%) pollutant removal Special plant & soil requirements Images: Stormwater Center, Minnesota Water
Stormwater Wetlands Constructed wetlands Gravel Wetlands Wet detention basins Mosquito breeding concern Images: UNH, Watershed Texas, Greenville County South Carolina
Images: Terra Genius, CalTrans Extended Dry Detention Basins Modified version of traditional detention basin Extended duration allows particles to settle out Designed for larger drainage areas
Images: Contech, StormTrap, Filterra Filter Systems Sand filters Tree boxes Proprietary systems
Proprietary Separators Can also be used for pre-treatment Maintenance & Upkeep Specialized filter media, systems Images: StormCeptor, VorTechs, VortSentry, StormFilter
Images: Wikipedia, Fairfax County Virginia Conveyance BMPs
Images: CalTrans, Oregon DOT, UC Santa Barbara Drainage Channels & Water Quality Swales Drainage channels: conveyance only Water quality swales: some treatment Pollutant removal depends on: Flow rate and velocity through swale Hydraulic residence time
Infiltration BMPs Often combined with other BMPs Groundwater recharge, not storm peak reduction Not suitable for every site: What are site soils? Groundwater elevation?
Dry Wells & Underground Structures Dry wells Multiple manufacturers Images: StormChambers, Contech, NYC.gov, StormTrap
Infiltration Trenches Small footprint Good for perimeters Images: Low Impact Development Center, Susdrain
Infiltration Basins Stormwater detention, with infiltration added Can include treatment (bioretention) Images: Ventura Stormwater, City of Ames Iowa, City of Sandy Oregon
Other BMPs Pervious Pavement/Pavers Green Roofs/Rain Barrels Detention Basins
Permeable Paving Multiple Types: Pervious concrete Porous asphalt Pavers Considerations: Cost/Maintenance Infiltration BMP Images: Metropolitan Area Planning Council, WIkipedia
Stormwater BMP Applications Small drainage areas easiest to handle Multiple BMPs work best as a system More intensive treatment = More $$$ Retrofits for existing systems Alternatives Analysis find the optimal design
Questions? Stormwater BMPs: Selection and Application David Cloutier, PE, CPESC Nobis Engineering, Inc. dcloutier@nobiseng.com (978)-703-6048 Images: Civil Engineering Photos