The White Paper Connecticut Association of Wetland Scientists 7 th Annual Meeting February 25, 2004 Robert Jontos, PWS, CPESC Land-Tech Consultants, Inc

The White Paper The White Paper

Connecticut Association of Wetland Scientists

7th Annual Meeting

February 25, 2004

Robert Jontos, PWS, CPESC

Land-Tech Consultants, Inc.Environmental Scientists and Engineers

Wetland BuffersWetland Buffers

February 25, 2003 CAWS 7th Annual Meeting - Buffers 2

Status of Buffers in Connecticut

Topics to be covered:

• Summary of 2003 Presentation

• Introduction

• Objectives

• Findings

• Recommendations


Status of Buffers in Connecticut

Summary of 2003 Presentation:

– Legal Authority - Municipal Inland Wetland and Watercourses Agencies can regulate activities outside of their jurisdictional areas provided that:

• Buffers are provided for in their regulations

• Proposed upland site activitieswill or may affect jurisdictional areas


Terminology Defined

“Setback Area” and “Non-disturbance Area”- Often used interchangeably with the term buffer, but not

interchangeable for the purposes of the white paper

- Physical dimension

- Vegetation may not be managed

“Upland Review Area”- Not a buffer, but a dimensioned distance from a wetland or

watercourse

“Riparian Area”- The land immediately adjacent to a watercourse

- Lake, pond, or stream


Vegetative Buffer - Definition

Common Names:

“Buffer Area”

“Vegetative Buffer

Strip” – VBS

Interchangeable terms

Definition:

Typically defined as a vegetative upland area (determined by soils, topography and vegetation) directly adjacent to a wetland or watercourse with ecological, hydrologic and physical connections to the wetland or watercourse.


Buffer vs Vegetative Buffer

“Buffer”• Setback, non-disturbance area, or upland review

area; a physical dimension only

“Vegetative Buffer”• Functional entity used to treat stormwater runoff,

and enhance/protect/preserve water quality.

Regulated Area or Setback

Regulated Area or Setback is a distance from a wetland or watercourse which is defined by local

Land Use Agencies

watercourse & wetland

Regulated area or setback

watercourse

floodplain

wetland

wetland

floodplainuplands

uplandsRiparian Area

Riparian Area is defined as the lands immediately adjacent to a watercourse up to the limits of the

floodplain

Vegetated Buffer

Vegetated Buffer shown – native planted strip between wetland/watercourse and upland existing

vegetation

Existing vegetation and turf

watercourse & wetland

vegetated buffer


General Setback

Wetland Setback

Watercourse Setback Buffer

87 40* 40* 13

Range (FT)

20 - 650

Range (FT)

15 - 100

Range (FT)

15 – 100

Range (FT)

50 - 200

* 16 COMMUNITIES WITH VARIABLE DISTANCES

19 COMMUNITIES USE RESOURCE SPECIFIC SETBACKS

6 COMMUNITIES INCREASE SETBACK WITH SLOPES > 10-15%

2 COMMUNITIES USE FLOOD BOUNDARIES

Summary of 169 Municipal Regulations “Regulated Areas”


20’ 25’ 50’ 75’ 80’ 100’ 150’ 200’ 250’ >250’

1 0 1 4 1 8 1 2 0 1

Number of Towns with setback distance




• Not all communities have setbacks cited in their regulations

• Setback distances cover a broad range of distances, variables (slope angle, land use)

• Some communities use resource specific setbacks (river, watershed, floodplain)

• None cite a methodology for determining “buffer” width


2003 Buffer Conclusions

1) Buffer regulations don’t consider individual buffer functions nor the characteristics or condition of the buffer.

2) Buffer size is either “fixed” or “variable”Fixed width – easily enforced, existing and

proposed conditions not considered

Variable width - Considers site specific conditions, trained staff, variability


2003 Buffer Conclusions

Combined Approach:a) Education – designers, reviewers

and “the Public”b) Accepted and defensible protocol

for design & applicationc) Combine with LID & BMPsd) Maintenance/Management

e) Enforcement


2004 Vegetative Buffer White Paper

-Drafted by CAWS members for use by designers and regulatory agencies & commissions

- Academically and legally critiqued

- Purpose: education, design parameters, review criteria, management methods


Vegetative Buffer White Paper

Motivation:

- Science based methodology for design, regulation and effective management of vegetative buffers

- Version 1.0 - Working document

- Initial focus: Protecting and improving water quality


Vegetative Buffer Functions

1. Sediment removal (filtration)

2. Nutrient removal (plant uptake & soil adsorption)

3. Stormwater runoff (filtration & infiltration)

4. Water temperature moderation

5. Habitat and wildlife diversity


Buffer Sizing and Design

General Considerations -“one size does not fit all”

1. Objectives must be defined

2. Watershed position

3. Existing plant composition and density

4. Soils and Slope conditions (above & within buffer area)



Objectives:

1. Runoff filtration & infiltration

2. Streambank stabilization

3. Downstream flood attenuation

4. Wildlife habitat and corridors



Watershed position

1. Position does impact effectiveness

2. Buffering low order streams (1st-3rd), greater impact on water quality than wider buffers on large order streams – sediment source control



Existing plant composition and density

• Inventory existing species & density• Use “undisturbed” riparian community as

guide for enhancement/management• Ground cover critical element• Microtopgraphy within buffer area may

permit channeling of surface flow



Soils and Slope

Placement of well developed vegetative buffer strip (VBS) between erosive soils or soils exposed for extend periods reduces the velocity of runoff, thus reducing scour potential & sediment movement, and promotes sheet flow/infiltration


Buffer Size: Recommend Width for Water Quality

Approaches:

1. Regression analysis (Dillaha, et al., 1986) quantify buffer performance based on sediment, nitrogen and phosphorus removal

- Based on limited database, low flow rates (1.8L/s-m), narrow buffers <11.2 meters

- Site specific, slope not considered

- Requires subshed runoff to be calculated using standard engineering analysis

- Trial and error, checking tool


2. Welsch (1991) “Three Zone Method”

3. Sweeney (1992) modified “Three Zone” • fixed width Three Zone method for riparian forest

restoration

4. Westchester Environmental Management Council Method

• considers slope



Zone Width Purpose

Zone #1- Trees T.O.B to 5-8 m (15-25 ft) landward

Bank stabilization, moderate water temperature, promote algal growth, woody debris input, nutrient & detritus processing

Zone #2 – Trees & Shrubs

Landward edge of zone #1 to 3 to >100 m (10 - 200 ft)

Long-term sequestering of nutrients, sediments, and other pollutants, runoff infiltration

Zone #3- Grass or Herbaceous

Upland edge of #2 to 3 meters if used with zones 1 & 2, or 10.6 m (35 ft) alone.

Slow runoff, filter sediment promote infiltration, nutrient uptake, and sheet flow

(after Welsch, 1991)

Welsch (1991) “Three Zone Method”


Zone Width Purpose

Zone #1- Trees T.O.B to 4.6 m (15 ft) landward

Bank stabilization, moderate water temperature, promote algal growth, woody debris input,nutrient & detritus processing

Zone #2 – Trees & Shrubs

Landward edge of zone #1 to 18 m (60 ft)

Long-term sequestering of nutrients, sediments, and other pollutants, runoff infiltration

Zone #3- Grass or Herbaceous

Upland edge of zone #2 to 6.1 m (20 ft) landward

Slow runoff, filter sediment promote infiltration, nutrient uptake, and sheet flow

Sweeney (1992) Modified Three Zone Method

(after Sweeney, 1992)


Westchester County Method (1981)

• Minimum starting buffer width of 7.6 m (25 ft) • Increase buffer width by 0.9 meters (3.0 ft) for

each percent (%) increase in slope• Reduce buffer width by 0.1 meters (1.0 ft) for

each 0.9 meter (3 ft) of adjacent brush or woodland growth in good hydrologic condition

• Slopes >15% and/or slope runs > 200 ft and/or if filter is in dense shade or subject to heavy traffic, then temporary E&S controls and level spreader required


Selecting Buffer Widths: Additional Methods

• Connecticut Guidelines for Sediment and Erosion Control 2002 (50 ft to >1600 ft, 10% max. slope )

• Finley (1987) 15m (49 ft) starting width, increase 6m (19.7 ft) for each 5% increase in slope to a maximum slope of 25% and 150 feet width


Effective Buffer Area

Drainage Area

Riparian Buffer Zone

Effective Buffer Area

Wetland

Watercourse

Modified after Dossky et al. 2002

Gross Area of Buffer


Physical Environment

Soil Type – Drainage class/hydrologic group, erodibility Index

Topography – Greater the slope, faster the runoff, increase in soil erosion and sediment transport potential

“Area Ratio” - size of the drainage area contributing flow to the buffer, smaller the ratio, better the treatment


Area Ratio

watercourse

V.B.S

Drainage area



• Observations from the literature reviewed:• Width of VBS range between 2 - 500

meters/ 6.5 – 1,640 feet• Majority fall within 4.6 – 15 meters/15 – 49

feet. • Slope of buffer >10%, increase in width• Area ratio range 15:1 to 5:1 or less • Plant species composition affects efficiency


Plant Composition:

1. Grass – effective in removing coarse sediment and absorbing nutrients

2. Shrubs – maintain soil infiltration capacity

3. Combined grass and shrub filter more effective than grass alone

4. Ideal VBS is transition - grass, shrubs and trees



Plant Type vs. Removal Efficiency

Function Grass Shrubs Trees

Sediment Trapping High Medium Low

Filtration of Sediment Borne Nutrients, Microbes & Pesticides

High Low Low

Soluble Nutrients & Pesticides Removal Medium Low Medium

Flood Conveyance High Low Low

Reduce Streambank Erosion Medium High High

Mod. after Fisher & Fischenich, 2000


Plant Species, Numbers & Sizing

• Diversity of plant species within the buffer insure better success in response to variable environmental conditions (temp., herbivory water levels)

• A mixture of native herbaceous, shrub and tree species appropriate to the environment

• Habitat Diversity – variable amounts and types of plants, over microtopography



Tree Diversity

Number of Trees Planted Max. % of any one species

10-19 50%

20 - 39 33%

40 or more 25%

•Fisher and Fischenich, 2000)



Tree Planting Densities:

• 400/acre, 10” to 48” tall

• 200/acre, 15 ft tall

• 3 - 5 ft tall saplings spaced 15 feet on center may reduce negative impacts of browse, better survival

• Shrub planting – 2-3 feet tall, 5-8 feet on center


Plant Survival

Management Measures:• Use of plastic tree shelters with mulch and

herbicide, best seedling survival• Grasses harvested to encourage dense

growth, remove nutrients• Control invasives – mechanical, hand,

mulch, herbicide or prescribed burning• Remove sediment, fill rills and re-create

microtopography and re-seed/replant.


Observations & Recommendations

1. Vegetative buffer strips (VBS) are an effective BMP in urban and agricultural settings. One-size does not fit all, bigger may not be better due to channelized flow

2. Vegetation provides E&S control, non-point nutrient and pollutant removal, promotes infiltration



3. Buffer Effectiveness dependent upon:a) Species and density of vegetation within the

bufferb) Soil type above and within the bufferc) Slope of the buffer and contributing watershed area – microtopgraphyd) Length of the buffer (width of flow path) and

Area ratioe) Proposed land use above the buffer



4. VBS can be used as stand alone BMP, but are more effective when used in combination with other BMPs/LIDs

5. Long continuous buffer strip rather than segmented, can be variable in width depending on site conditions and design goals



6. Combination of grass, shrub & trees in sequence more effective in removing sediment, adsorbing nutrients, other NPS pollutants and maintaining soil infiltration

7. Native species should be used to enhance or create VBS in combination with long-term management plan.



8. Infiltration is key to reducing sediment and adsorbing pollutants

9. Smaller area ratios (5:1) are more effective in sustaining filtering efficiency of VBS

10. Buffer widths – 5m (16ft) to 15m (49ft) effective in reducing sediment loads and protecting water quality



• In Urban/agricultural areas with slopes of <10% with limited area, 5m wide grass VBS are effective in removing significant amounts of NPS pollutants

• In watersheds under development with slopes 10% or less and typical soil transitions, a minimum buffer of 10m (33 ft) can be effective.



• With slope conditions >10% and:– wetlands & watercourses with moderate to

high functional values or critical habitats (bogs, fens, wetland complexes)

– or where water quality is a critical issues (public water supply watershed or impaired watercourse)

A minimum buffer of 10m + (50 ft or greater) should be considered with BMPs



• Functional goals of the Vegetative Buffer Strip must be clearly defined and a management plan prepared to establish and maintain those functional goals both during and after development


Conclusion

Now its your turn!• Version 1.0 will be posted on the CAWS

website for three months for review and comment.

• White Paper committee will review the comments and edit the paper.

• Final version will be posted in August of 2004.


Information

• CAWS web address:www.ctwetlands.org

• My email address: [email protected]

• please send comments and edits to R. Jontos for distribution to the review committee

• Please track your changes or use colored fonts or highlighting to make your edits or comments stand out

The White Paper The White Paper

Connecticut Association of Wetland Scientists

7th Annual Meeting

February 25, 2004

Robert Jontos, PWS, CPESC

Land-Tech Consultants, Inc.Environmental Scientists and Engineers

Wetland BuffersWetland Buffers

Documents

The White Paper Connecticut Association of Wetland Scientists 7 th Annual Meeting February 25, 2004 Robert Jontos, PWS, CPESC Land-Tech Consultants, Inc