The Green Corridor Project

Green Infrastructure and Stormwater Pre-Treatment Concept “Silva Cell” Crate System “Freno” Modular Flow-Through

Planters Micro-Pool Stormwater Swale

Streetscape Planting Concepts

Design Considerations: Expected Pollutants

• Landscaping sites (fertilizers -- phosphorus and nitrogen): greater cell depth will help filter these.– Studies show that removal of these pollutants increases with the depth of

the bio-retention cell, reaching removal levels up to 80% for phosphorus and 60% for nitrogen (TKN) with sufficient depth (study results relating to nitrogen vary).

• Parking lot or streetscape applications (metals, oils, grease and solids): Thicker mulch layer– Studies support that a significant mulch layer will effectively remove

greater than 90% of copper, zinc and lead.

In urban areas where heavy metals are the focal pollutants, shallow bioretention facilities with a significant mulch layer may be recommended. In residential areas, however, where the primary pollutants of concern are nitrogen and phosphorus, the depth dependence will require deeper cells that reach approximately 2 to 3 feet

http://www.lid-stormwater.net/bio_benefits.htm

Bio-retention removes Pollutants (survey of studies)

Pollutant Pollutant RemovalCopper 43%-97%

Lead 70%-95%

Zinc 64%-95%

Phosphorus 65%-87%

Total Kjeldahl Nitrogen (TKN) 52-67%

Ammonium (NH4+ ) 92%

Nitrate (NO3-) 15%-16%

Total nitrogen (TN) 49%

Calcium 27%

Bioretention BMP, http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.

Fairfax Boulevard Stormwater Pre-Treatment Filtration Based System

Filtration Systems provide temporary storage and filtration of stormwater, contributing to:

• Water quality control• Percentage Reduction of Stormwater Volume• Channel protection,• Overbank protection, and• Extreme flood control

• Used where soils are not suitable for infiltration

• The system stores and treats stormwater before returning it to the stormwater drainage system typically through a perforated under-drain.

• Use of small scale, natural drainage features to slow, clean and capture runoff to reduce the impacts of development on rivers, streams, lakes, coastal waters, and ground water.

Fairfax Boulevard Lancaster Cir. To 6th Ave

“Silva Cell” Crate System

Suspended Concrete and Brick Paving

Stormwater Distribution/Irrigation Lines

“Silva Cell” Structural Crates Containing Uncompacted

Engineered Soils for Tree Root Growth and Water RetentionPerforated Under Drains for

Large Storm Events

Geomembrane Liner to prevent Infiltration beyond the Structural Crate System

Connection to the Underground Storm Sewer System

How the “Silva Cell” Crates works

Washington DC- SW 1st street- Silva Cells 2008- 2010

Willow Oak (Quercus phellos) Planted 1985, 25 years old in 2010Avg DBH 16 inches; Avg 44 feet; Avg Soil Volume 700 cubic feet

City of Charlotte Soil Vaults- 1985

Fairfax Boulevard 6th Ave. to 12th Ave.

Modular Flow-Through Planters

Precast Concrete Curb Drain/Inlet

Gravel Filter Strip

Overflow Drain for Large Storm Events

Geomembrane Liner to prevent Infiltration beyond the Flow-Through Planter

Modular Precast Concrete Flow-ThroughPlanter Walls

Connection to the Underground Storm Sewer System

Herbaceous Plantings

2 inch Mulch Layer

Engineered Soils

Sand and Gravel Drainage Bed

Perforated Under Drains

“Freno” Modular Flow-Through Planters

Life Cycle Benefits

• As a modular system the Freno Flow-Through Planter can be removed and reused.

• Similarly, components can be

removed and reconfigured if the site is redesigned.

• The system can be repaired with replacement parts if accidental damage occurs.

Suggested Modular Flow-Through Planter Maintenance

Activity Schedule

• Water plants daily for 2 weeks At project completion

• Inspect soil and repair eroded areas• Remove litter and debris• Re-mulch void areas

As Needed

• Remove and replace dead and diseased vegetation Twice per year

• Add mulch• Cut back herbaceous plantings during winter dormancy Once per year

• Test soil treatment performance and replace soil/plants Testing 3 years

As needed (7-10years)

Bioretention BMP, http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm

Fairfax Boulevard 6th Ave. to Fairfax

CrossingMicro-Pool

Stormwater Swale

Landscape Micro-Pool Plantings w/ Street Trees

Weir Wall Spillways

Overflow Drain for Large Storm Events

Connection to the Underground Storm Sewer System

3 ft. Turf Filter Strip

Herbaceous Plantings with Formal Planting Border

Perforated Under Drains

Layered and “Over” Planting Approach to Micro-Pool Planting

Suggested Micro-Pool Weir Planting Maintenance

Activity Schedule

• Water plants daily for 2 weeks At project completion

• Inspect soil and repair eroded areas• Remove litter and debris• Re-mulch void areas

As Needed

• Mow monthly for the First year First year Only

• Add mulch• Mow and/or cut back plantings during winter dormancy• Selectively Remove Invasive exotic Plants

Once per year

• Re-plant eroded and bare areas after large storm events As needed

Bioretention BMP, http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm

The Key to the Overall Success of the Micro-Pool Planting is to not

over maintain after the First Year

•Mow and/or cutback once a year

•No irrigation needed

•No fertilizing needed

Bio-diverse Planting of Street Trees

Layered and “Over” Planting Modular Flow-Through Planters

Micro-Pool Strategic Combination Plantings

Brick and Concrete Paving between Lancaster Cir. And 6th Ave.