Larry Coffman, President Stormwater Services, LLLP lcoffman ...
Larry Coffman, President Stormwater Services, LLLP lcoffman ... Larry Coffman, President Stormwater Services, LLLP lcoffman ...
Larry Coffman, President Stormwater Services, LLLP lcoffman@filterra.com 301-580-6631
- Page 3 and 4: The first Rain Garden in Virginia,
- Page 5 and 6: What is Bioretention? Filtering and
- Page 7 and 8: Rain Gardens in OR
- Page 9 and 10: Rain Gardens in S. CA
- Page 11 and 12: Rain Gardens in Auckland, NZ
- Page 13 and 14: Rain Gardens in WI
- Page 15 and 16: Rain Gardens in MN
- Page 17 and 18: Village Homes Davis, CA
- Page 19 and 20: 2008 Somerset, Maryland - Rain Gard
- Page 21 and 22: 2008 Somerset, Maryland - Rain Gard
- Page 23 and 24: Bioretention Advantages • Univers
- Page 25 and 26: What were the drivers for change?
- Page 27 and 28: Number in 90 Meter Station 60 50 40
- Page 29: Maintenance Burdens
- Page 32 and 33: THE BIORETENTION CONCEPT Original D
- Page 34 and 35: New York State Stormwater Managemen
- Page 36 and 37: Bioretention Pollutant Removal Univ
- Page 38 and 39: Pollutant Removal - Plant Microbe
- Page 41 and 42: Interesting Study Findings • Mulc
- Page 43 and 44: Pretreatment doesn’t extend the l
- Page 47 and 48: Division Street Planters
- Page 49 and 50: • Depth should vary based on type
<strong>Larry</strong> <strong>Coffman</strong>, <strong>President</strong><br />
<strong>Stormwater</strong> <strong>Services</strong>, <strong>LLLP</strong><br />
<strong>lcoffman</strong>@filterra.com<br />
301-580-6631
The first Rain Garden in Virginia, located in a turning<br />
circle in front of St. Stephens School, Alexandria.
St. Stephens Rain Garden- 5 years later.
What is Bioretention?<br />
Filtering and/or infiltrating stormwater runoff through a terrestrial<br />
aerobic (upland) plant / soil / microbe complex to remove<br />
pollutants through a variety of physical, chemical and biological<br />
processes.<br />
The word “Bioretention” was derived as a technical term to<br />
describe the process of the “biomass” (plant / microbe complex)<br />
“retaining” pollutants of concern such as N, P and heavy metals.<br />
The term “Rain Garden”<br />
“Rain Garden” was derived to market Bioretention to<br />
the general public.
“CULTIVATING<br />
HARMONY IN A<br />
THEMED<br />
GARDEN”
Rain Gardens in OR
Rain Gardens in Australia
Rain Gardens in S. CA
Rain Gardens in FL
Rain Gardens in Auckland, NZ
Rain Gardens in Bose, ID
Rain Gardens in WI
Rain Gardens in MA
Rain Gardens in MN
Rain Gardens in MD
Village Homes<br />
Davis, CA
1992 Somerset, Maryland - Rain Gardens<br />
First Residential Application
2008 Somerset, Maryland - Rain Gardens
1992 Somerset, Maryland - Rain Gardens<br />
First Residential Application
2008 Somerset, Maryland - Rain Gardens
• Education<br />
Responsibility<br />
Function<br />
O & M<br />
• Enforcement<br />
Easements<br />
HOA<br />
Community Standards<br />
• Economics<br />
Property Values<br />
Added Value<br />
Ease of Maintenance
Bioretention Advantages<br />
• Universally applicable<br />
• Economically sustainable<br />
– Lower construction, maintenance & operation costs<br />
• Ecologically sustainable<br />
• Multiple benefits<br />
– Water Quality<br />
– Water Quantity<br />
– Air, Energy, Heat Island, Carbon Sequestration …<br />
• Added value (nature sells!)<br />
• Encourages public stewardship
THE BIORETENTION CONCEPT<br />
Original Design P.G County 1993
What were the drivers for change?<br />
• Problems with ponds (performance and<br />
liabilities).<br />
• Maintenance / inspection of private onsite<br />
systems.<br />
• Costs of growing infrastructure.<br />
• Urban retrofit.<br />
• Restoring ecological integrity of receiving<br />
waters.
Limitations<br />
• Safety / Health<br />
Maintenance<br />
• Inspection / Maintenance<br />
• Inefficient Pollutant Removal<br />
• Temp / Sediment / Frequency /<br />
Volume<br />
Pond Liabilities<br />
Safety
Number in 90 Meter Station<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
16<br />
39<br />
29<br />
20 20<br />
11<br />
10<br />
5<br />
7<br />
20<br />
11<br />
31<br />
19<br />
28<br />
Good Hope Tributary To Paint Branch<br />
15<br />
43<br />
13<br />
10<br />
7<br />
Population Estimates<br />
Adults YOY<br />
28<br />
13 13<br />
17<br />
20<br />
11<br />
15<br />
9<br />
19<br />
10<br />
51<br />
27<br />
22 22<br />
17<br />
16<br />
28<br />
27<br />
34<br />
21<br />
17<br />
15<br />
1979<br />
1980<br />
1981<br />
1982<br />
1983<br />
1984<br />
1985<br />
1986<br />
1987<br />
1988<br />
1989<br />
1990<br />
1991<br />
1992<br />
1993<br />
1994<br />
1995<br />
1996<br />
1997<br />
1998<br />
1999<br />
2000<br />
2001<br />
2002<br />
2003<br />
Year of Survey<br />
22<br />
5<br />
14<br />
8<br />
15<br />
4<br />
11<br />
4<br />
0
45<br />
40<br />
35<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
B-IBI w/BMPs B-IBI w/o BMPs<br />
0 10 20 30 40 50 60 70<br />
Watershed Urbanization (%TIA)<br />
Figure 2: Showing the lack of mitigating influence of<br />
structural BMPs on biologic conditions in Puget Sound<br />
lowland streams (Horner and May, 2000).
Maintenance Burdens
Issues<br />
• Outdated / Inflexible Regulations & Design<br />
Guidance<br />
• Construction Inspection / Enforcement
THE BIORETENTION CONCEPT<br />
Original Design P.G County 1993
X<br />
2’<br />
Under Drain<br />
Bioretention<br />
Shallow Ponding - 4” to 6”<br />
• Mulch 3”<br />
• Soil Depth 2’ - 2.5’<br />
• Sandy Top Soil<br />
• 65% Sand<br />
• 20% Sandy Loam<br />
• 15% Compost<br />
• Under Drain System<br />
• Plants
New York State<br />
<strong>Stormwater</strong> Management Design Manual<br />
April, 2008<br />
Examples of Outdated<br />
Information
Why shouldn’t there be a preference for<br />
better performing technology?
Bioretention Pollutant Removal<br />
University of Maryland<br />
Box Experiments<br />
Cumulative<br />
Depth<br />
Phos-<br />
(ft) Copper Lead Zinc phorus TKN Ammonia Nitrate<br />
Removal Efficiency (%)<br />
1 90 93 87 0 37 54 -97<br />
2 93 99 98 73 60 86 -194<br />
3 93 99 99 81 68 79 23<br />
Field 97 96 95 65 52 92 16<br />
Dr. Allen Davis, University of Maryland
Stage 1. Capture<br />
Pollutant Removal Mechanisms<br />
“Physical Physical / Chemical / Biological”<br />
Processes<br />
Sedimentation<br />
Filtration<br />
Adsorption<br />
Absorption<br />
Cation Exchange Capacity<br />
Stage 2. Sequester<br />
Microbial Action (aerobic / anaerobic)<br />
decomposition / nitrification /<br />
denitrification<br />
Evaporation / Volatilization<br />
Cycling Nutrients / Carbon / Metals<br />
Biomass Retention (Microbes / Plant)<br />
System Components<br />
Storage<br />
Mulch<br />
Media<br />
Surface Area<br />
Organics<br />
Microbes<br />
Plants
Pollutant Removal - Plant Microbe<br />
• Phytoremediation<br />
– Translocate<br />
– Accumulate<br />
– Metabolize<br />
– Volatilize<br />
– Detoxify<br />
–Degrade<br />
• Exudates<br />
• Bioremediation<br />
• Soils<br />
– Capture / Immobilize<br />
Pollutants
Burnsville, MN<br />
Rainwater Gardens<br />
• Urban Retrofit<br />
• 90% Runoff Reduction<br />
• 85% Participation<br />
For more information, contact<br />
Barr Engineering Company,<br />
4700 W. 77th St., Suite 200,<br />
Minneapolis, MN 55435,<br />
(952)832-2600 or (800)632-<br />
BARR or Fax (952)832-2601.
Interesting Study Findings<br />
• Mulch and Metals<br />
• Plants and Metals<br />
•P Uptake<br />
• Capacity / Longevity<br />
• Time For Reactions (Residence Time)<br />
• Oil and Grease 95% Removal<br />
• 90% Bacteria Removal
Don’t use filter fabric use a bridging stone (pea gravel)<br />
No Need for stone diaphragm!
Pretreatment doesn’t extend the life of the system.<br />
The issue is to ensure proper maintenance!
Criteria severely restrict the use of bioretention.<br />
Flexibility is key!
Division Street Planters
Buckman Heights courtyard with infiltration garden
• Depth should vary based on type of plants, target<br />
pollutants, site constraints, etc.<br />
• Generally 2 to 2.5 feet.
No soils are the same!
Sizing should be based on actual “K” factors
City of Portland , OR<br />
Low Flow – 0.5” to 1” / Hour<br />
“Soaker”<br />
Sand / Municipal Compost<br />
Ocean City, MD<br />
High Flow - + 100”-120 ” / Hour<br />
Filterra<br />
Corse Sand / Peat
Low Flow Media<br />
2 to 10 inches / hour<br />
Peat / Sand / Aggregate Matrix - PSD<br />
Peat 15 to 20% by volume<br />
Clay
High Flow Media<br />
10 to 50 inches / hour<br />
Peat Sand / Aggregate Matrix - PSD<br />
Peat 5 to 10% by volume<br />
Clay
Louisburg Bioretention Cells<br />
• Soil Media:<br />
– Nominally 0.75 m Deep<br />
– 60% Sand<br />
– 40% “Ballfield Mix”<br />
• Low PI (1-2) (1 2) fill<br />
– 85% Sand<br />
– 10% Fines<br />
– 5% Organics<br />
• Constructed Spring 2004
US Army Corps<br />
of Engineers®<br />
Engineers<br />
Darryl J. Calkins<br />
Nov 6, 2003<br />
US Army Cold Regions Research and Engineering Laboratory<br />
Hanover, New Hampshire
State of VT <strong>Stormwater</strong> Management<br />
Manual-Comments<br />
• Infiltration systems & ground freezing<br />
– The moisture content of the soil at freeze-up is critical<br />
as it occupies air void space and during freezing takes<br />
up space that could be available for infiltration
Bioretention Cold Weather<br />
Climate Considerations<br />
• Good Drainage!<br />
• Sandy Course Media<br />
• Combination Filtration / Infiltration<br />
• Provide Extra Surface Storage<br />
• Selection of Plants<br />
• Proper Location and Use<br />
• Reduced Salt or use Alternative Deicers<br />
• Ground Water Levels<br />
• Maintenance
Wilmington, NC
Lessons Learned<br />
Failures Due to:<br />
• Use of Old Design Standards<br />
- clay / organic / K factor<br />
• Poor Drainage<br />
- Under drain design / Geo-fabrics / Saturated soils<br />
• Media Variability<br />
- Reliable Sources<br />
• Contractor Substitutes<br />
• Contamination<br />
- P, N and Heavy Metals<br />
• Sizing / Space<br />
• Maintenance<br />
- Can be high