Session 1E Non-Structural BMPs 1 Chesapeake Bay Storm w ater Training Partnership
A A Agenda Agenda d d Site Design (self-crediting) Site Design (self crediting) Soil Amendments Simple Disconnection Si l Di ti Sheet Flow Grass Channels Site Plan courtesy of 2 Chesapeake Bay Storm w ater Training Partnership
Key Resources on your disk y y • October 2010 Webcast Archive: Disconnection • Disconnection Webcast Resource Sheet Disconnection Webcast Resource Sheet • Filter Strip and Soil Amendments Presentation Relevant DCR Design Specifications : • – No. 1 Disconnection – No. 2 Sheet Flow – No 4 Soil Amendments No. 4 Soil Amendments • Urban Watershed Forestry Manual Part 2: Conserving and Planting Trees at Development SitesThe Runoff Reduction Th Theory Presentation P t ti • Urban Watershed Forestry Manual Part 3: Urban Tree Planting Guide g 3 Chesapeake Bay Storm w ater Training Partnership
Non-Structural Practices Non Structural Practices Direct growth to identified Encourage infill and re- areas; areas; development; development; Protect sensitive aquatic Educate on material resources; disposal/recycling Establish buffers along Establish buffers along Spill Prevention/Clean Up Spill Prevention/Clean Up stream and other waters; Identify and eliminate illicit Maintain existing runoff discharges patterns and Tc; patterns and Tc; Promote street sweeping Promote street sweeping Minimize impervious surfaces; Develop Public Minimize disturbance of soils Education/Participation and vegetation; and vegetation; programs programs 4 Chesapeake Bay Storm w ater Training Partnership
Non Non- -Structural Practices as part of the Structural Practices as part of the Runoff Reduction Method Runoff Reduction Method 1. Minimization & Avoidance 1. Minimization & Avoidance 2. Reforestation 3. Soil compost amendments p 4. Impervious disconnection 5. Sheet flow to Vegetated Filter and g Conservation Areas (or Buffers) 6. Grass channels 5 Chesapeake Bay Storm w ater Training Partnership
Sit D Site Design Sit D Site Design - Things to Consider i i Things to Consider Thi Thi t C t C id id Riparian Buffers Riparian Buffers Wetlands and Stream Channels Existing Woods Existing Woods Transitional buffers Soils Constraints (Texture, HSG, Perm., Bedrock, Water Table) Slope Constraints Access to Site Access to Site 6 Chesapeake Bay Storm w ater Training Partnership
Example 14.98 acre development Example 14.98 acre development p p p p 7 Chesapeake Bay Storm w ater Training Partnership
Identify Water Resources and Forested Areas Identify Water Resources and Forested Areas y 8 Chesapeake Bay Storm w ater Training Partnership
Soils Investigation Soils Investigation g 9 Chesapeake Bay Storm w ater Training Partnership
Determine Limits of Constraints Determine Limits of Constraints 1 0 Chesapeake Bay Storm w ater Training Partnership
Typical Development Patterns Typical Development Patterns yp yp p p 14.98 Acres 25 ½ acre lots 1 1 Chesapeake Bay Storm w ater Training Partnership
Alternative Development Alternative Development p 14.98 Acres 25 ¼ acre lots 1 2 Chesapeake Bay Storm w ater Training Partnership
Eff Eff Effects of Typical Layout Effects of Typical Layout t f T t f T i i l L l L t t Clearing of entire site (disturbed soils) Cl i f ti it (di t b d il ) Significant Impacts to Wetlands and Stream Channels Channels Impacts to designated Riparian corridors Increase in Impervious Cover Increase in Impervious Cover Directly Connected Drainage Systems 1 3 Chesapeake Bay Storm w ater Training Partnership
LID Resources Report: LID Resources Report: Performance Standards 1 4 Chesapeake Bay Storm w ater Training Partnership
Minimization & Avoidance Minimization & Avoidance Design Goal : Allow/Promote Simple, Low Maintenance All /P t Si l L M i t Practices As Part of a Treatment Train Approach to Help Meet the Runoff Reduction Approach to Help Meet the Runoff Reduction Goal. 1 5 Chesapeake Bay Storm w ater Training Partnership
Start By Reducing Clearing and y g g Preserving Highly Permeable Soils • R d Reduces runoff ff coefficient from pervious areas pervious areas • Increases runoff Increases runoff reduction rates for non-structural practices in poor soils 1 6 Chesapeake Bay Storm w ater Training Partnership
Disturbed Soils Increase the Runoff Coefficient For Urban Turf Coefficient For Urban Turf Runoff Coefficients for Use for Different Pervious Areas 1 Hydrologic y g Undisturbed Disturbed Restored Restored Soils 2 Soils 3 Soils 4 Soil Group and Reforested 0 .0 2 0 .1 5 0 .0 5 0 .0 2 A A 0 .0 3 0 .2 0 0 .0 6 0 .0 3 B 0 .0 4 0 0 4 0 2 2 0 .2 2 0 .1 0 0 1 0 0 0 4 0 .0 4 C C 0 .0 5 0 .2 5 0 .1 2 0 .0 5 D 1 Source: CWP and CSN (2008) and Pitt (2004) 2 Portions of a new development site, outside the limits of disturbance 3 Previously developed sites, and any site area inside the limits of disturbance 4 Pervious areas on the site restored per DCR BMP Spec 4 1 7 Chesapeake Bay Storm w ater Training Partnership
We Have A Lot of Managed Turf in g the Bay! For every acre of new impervious cover, we create 3 acres of managed turf 3 acres of managed turf cover. What are the hydrologic h h h d l implications? 1 8 Chesapeake Bay Storm w ater Training Partnership
1 9 Chesapeake Bay Storm w ater Training Partnership
Disturbed Soils Are Not Very Pervious and Ineffective in Treating Stormwater and Ineffective in Treating Stormwater • Top Soil is Stripped • Soil Structure is Lost • Subsoils are Compacted Compacted • Reduced Water Holding Capacity Holding Capacity • Low Infiltration Rate • High Nutrient g Concentrations • Erosion & Runon to I Impervious Cover i C 2 0 Chesapeake Bay Storm w ater Training Partnership
S il A S il A Soil Amendments Soil Amendments d d t t 2 1 Chesapeake Bay Storm w ater Training Partnership
Soil Amendments Reduce the Runoff Coefficient For Urban Turf Coefficient For Urban Turf Runoff Coefficients for Use for Different Pervious Areas 1 Hydrologic y g Undisturbed Disturbed Restored Restored Soils 2 Soils 3 Soils 4 Soil Group and Reforested 5 0 .0 2 0 .1 5 0 .0 5 0 .0 2 A A 0 .0 3 0 .2 0 0 .0 6 0 .0 3 B 0 .0 4 0 0 4 0 2 2 0 .2 2 0 .1 0 0 1 0 0 0 4 0 .0 4 C C 0 .0 5 0 .2 5 0 .1 2 0 .0 5 D 1 Source: CWP and CSN (2008) and Pitt (2004) 2 Portions of a new development site, outside the limits of disturbance 3 Previously developed sites, and any site area inside the limits of disturbance 4 Pervious areas on the site restored per DCR BMP Spec 4 2 2 Chesapeake Bay Storm w ater Training Partnership
C C Compost and Incorporation Depths Compost and Incorporation Depths t t d I d I ti ti D D th th Contributing I m pervious Cover to Soil Am endm ent Area Ratio 1 I C/ SA = 0 2 I C/ SA = I C/ SA = I C/ SA = 1 .0 3 0 .5 0 .7 5 Com post depth 2 to 4 5 3 to 6 5 4 to 8 5 6 to 1 0 5 to 3 to 6 to 8 6 to 0 ( in) 4 ( i ) 4 I ncorporation 6 to 1 0 5 8 to 1 2 5 1 5 to 1 8 5 1 8 to 2 4 5 Depth ( in) I ncorporation Rototiller Rototiller Subsoiler Subsoiler Method Method Notes: 1 IC = contrib. impervious cover (sq. ft.) and SA = surface area of compost amendment (sq. ft.) 2 For amendment of compacted lawns that do not receive off ‐ site runoff For amendment of compacted lawns that do not receive off ‐ site runoff 3 In general, IC/SA ratios greater than 1 should be avoided 4 Average depth of compost added 5 Lower end for B soils, higher end for C/D soils 2 3 Chesapeake Bay Storm w ater Training Partnership
Impervious Disconnection p Simple Disconnection Si Simple disconnection l di ti Compost amended flow path Rain garden (Urban Planter) Rain garden (Urban Planter) Infiltration Rainwater Harvesting 2 4 Chesapeake Bay Storm w ater Training Partnership
Two Types of Disconnection Simple Disconnection : rooftops and/or on-lot residential impervious surfaces are directed to res dent al mperv ous surfaces are d rected to pervious areas; Alternative disconnection : the use of compensatory practices where the space p y p p required for simple disconnection may not be available, or enhanced performance is desired: 2 5 Chesapeake Bay Storm w ater Training Partnership
Simple Disconnection Simple Disconnection 2 6 Chesapeake Bay Storm w ater Training Partnership
Simple Disconnection Simple Disconnection Filter corridors from the downspout to the street Level spreader to distribute runoff over a ten foot width ten foot width Minimum and maximum • Length; Length; • Width; and • Slope criteria 2 7 Chesapeake Bay Storm w ater Training Partnership
Summary of Stormwater Function Summary of Stormwater Function provided by Simple Disconnection provided by Simple Disconnection id d b Si id d b Si l Di l Di ti ti 2 8 Chesapeake Bay Storm w ater Training Partnership
Si Si Simple Disconnection Design Criteria Simple Disconnection Design Criteria l Di l Di ti ti D D i i C it C it i i 2 9 Chesapeake Bay Storm w ater Training Partnership
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