Newsletter

October 2001

DEPARTMENT OF ENVIRONMENTAL PROTECTION
BUREAU OF RESOURCE PROTECTION
WETLANDS AND WATERWAYS PROGRAM
1 WINTER STREET, BOSTON MA 02108

DRAFT SUMMARY MASSACHUSETTS INLAND WETLAND REPLICATION GUIDELINES: A DRAFT SUMMARY OF KEY POINTS

THE NEED FOR GUIDANCE
A recent study conducted by the University of Massachusetts found that the majority of wetland replication projects undertaken in the Commonwealth do not meet the minimum performance standards in the Wetlands Protection Regulations.

The study summarized the reasons for the lack of success of replication sites as follows:

1) Inadequate wetland hydrology;
2) Poor vegetation replanting plans; or
3) Replication areas built smaller than required in the plans.

As a result, the Department of Environmental Protection (DEP) has developed guidance to aid in improving success rates of replication areas. Specifically, this replication guidance was written to help applicants prepare freshwater replication plans to comply with the Wetlands Protection Act (WPA) Regulations for bordering vegetated wetlands (310 CMR 10.55 (4)) and Section 401 of the Clean Water Act pertaining to Water Quality Certification (314 CMR 9.06(2)). An outline of the draft document is provided below.

If you would like a full copy of the draft document for review and comment please contact:

Lisa Rhodes
DEP Wetlands Program,
1 Winter Street, Boston MA 02108
(617) 292-5512; FAX (617) 292 – 5696;
Email: Lisa.Rhodes@state.ma.us
Final copies will be distributed to all Conservation Commissions.

DISCRETIONARY AUTHORITY
WPA regulations allow Conservation Commissions to approve up to 5000 square feet of bordering vegetated wetland (BVW) loss at their discretion (310 CMR 10.55(4)(b)). Replication should be required for all projects with unavoidable wetland loss including limited projects where possible. Decision-making under this discretionary authority should involve replication design considerations prior to approval of the replication plan.

It is often more cost effective to design a project to avoid wetland impacts than to propose replication, since the requirements to ensure a successful replication area can often take many years and dollars to complete.

SEQUENCING
 Replication is the final step in the process of wetland mitigation. Wetland mitigation involves reducing the impacts to wetland resources through a three-step process often referred to as “sequencing” as follows:

1) Avoidance of wetland impacts;
2) Minimizing necessary impacts as much as possible; and
3) Replicating losses that cannot be avoided.

Conservation Commissions should follow these steps when evaluating a project involving wetland replication.

PUBLIC INTERESTS
 For unavoidable impacts, the replication area should be designed to provide compensation for the public interests served by the existing wetland (public and private water supply, groundwater supply, flood control, storm damage prevention, prevention of pollution, fisheries, and wildlife habitat). The replication area design should also incorporate the opportunities and limitations of the mitigation site.

IMPORTANT COMPONENTS: HYDROLOGY, SOILS AND VEGETATION

Hydrology

Proper hydrology of the replication site is critical to a successful replication project. The final replication surface and ground water elevations are predicated on establishing site hydrology. High and low ground and surface water elevations must be established from data gathered in the local area. Applicants should begin data collection activities as far in advance of the project as possible.

  • Understanding hydrology requires knowledge of the anticipated seasonal groundwater depth, and the duration and frequency of both inundation and saturation (hydroperiod). This information should be described and compared to water regime characteristics for the proposed plantings.

Ideally, replication areas should not depend only on precipitation and sheet runoff. Successful replication areas require a seasonal source of groundwater as well as contributions from a surface water source.

  • Only the flood storage that the existing BVW provides should be designed in the replication areas. Additional, compensatory flood storage from upland floodplain should not be allowed in replication areas, unless it can be demonstrated that spring floods will not impact the replication area. Impacts from flooding can include inundation for extended periods, scour and deposition. Compensatory flood storage for all floodplain impacts, however, is required to be provided at the site of the impact.
  • In the event that a “constructed wetland” is used for stormwater purposes, the area shall not be included as replication credit for an impacted wetland resource area. If any stormwater is to be directed to a bona-fide replicated wetland, the stormwater is required to be treated prior to discharge in accordance with the Massachusetts Stormwater Management Policy.

Soils

  • The reuse of hydric soils from the impacted wetland to the replication area is preferred. Plans should include descriptive soil profile information from test pits (e.g. horizons, texture, organic matter, Munsell hue, value, chroma, and evidence of hydrologic influence).
  • Soil taken from areas where invasive species such as Phragmites and Purple Loosestrife are present should be avoided, especially if the invasive species represent a dominant monoculture. If soils are used where any invasive species are present, then the applicant does so at their own risk and may be responsible for remediation.
  • Surveying of sub grades and finished elevations should be conducted frequently during construction to inspect for soil settling and compaction.
  • Mitigation sites that are constructed on dense compacted C-horizons with a thin layer of A or O placed on top are at risk of failing. The goal for soils at the mitigation site should be to create soil profiles that approximate as closely as possible the soil profiles at the impact site (or nearest adjacent wetland).
  • Although not required, use of redox and pH meters in the replication area and adjacent wetlands will aid in replication success by allowing the applicant to make assumptions as to the likely success of long term hydric soil development and function.
  • Excavated hydric soils to be used at the mitigation site should be placed in the mitigation area as soon as possible to avoid dehydration. (if storage is required, soils should be stockpiled for as little time as possible and kept wet).

Vegetation

  • Plantings can be taken from the impacted wetland or brought from off-site. In either case, plans should provide detailed descriptions of the techniques proposed to establish vegetation, including methods for maintaining seed viability, rootstocks and plants during transplantation.
  • Plants should be kept moist and planted within one day of removal from existing wetland or as soon as possible. Consideration should be given to leaving existing mature upland trees on humocks within the replication site. Vegetated hummocks provide shade to the surrounding replication area and provide varied topography for wildlife habitat.
  • All planting should occur at the beginning or end of the growing season. Fall plantings should be done before the first frost. Shrubs and trees, however, may be planted up to November 15, weather permitting.

The regulations require that at least 75% of the surface of the replacement area shall be reestablished with indigenous wetland plant species within two growing seasons. In order to accomplish this, the hydrology and soil conditions must be appropriate for the types of vegetation proposed.

PERMIT APPLICATIONS
Applicants should provide the following information as part of their permit application:

  • Narrative descriptions of the wetland to be altered and the proposed wetland replication site;
  • Plan at scale of 1”=10’ to 1” = 40’ with contour lines at 1-foot intervals, including surveyed flag locations, benchmarks, or structures;
  • Surface area calculation;
  • Elevation and vegetation planting cross-sections.

CONSTRUCTION AND MONITORING

  • When possible, the replication area should be excavated and graded to the specifications in the plan before work in the existing wetland begins.
  • As part of the wetland construction process, site visits should occur at the following stages:

    1. Before excavation work begins in order to inspect site flagging;
    2. Before placement of hydric soils in replication area in order to inspect excavated elevations and likely post-construction ground water elevations for the replication area;
    3. After each stage of grading work is completed to inspect for soil settling, compaction, and finished elevations;
    4. During planting and seeding and after the first month of the growing season to inspect propagation techniques;
    5. After one growing season to observe vegetation development and regulatory compliance;
    6. After two growing seasons to determine vegetation development and regulatory compliance;
    7. After subsequent growing seasons, if a greater than 2-year monitoring program is required.

The Certificate of Compliance should not be issued until regulatory compliance is achieved.

APPENDICES

  • Sources of Planning Information
  • Replication Checklist
  • Example Monitoring Data Sheet
  • Common Mistakes and Problems
  • USDA Growing Seasons

CONTACT FOR FURTHER INFORMATION

If you would like a full copy of the draft document for review and comment please contact:

Lisa Rhodes
DEP Wetlands Program,
1 Winter Street, Boston MA 02108
(617) 292-5512; FAX (617) 292 – 5696;
Email: Lisa.Rhodes@state.ma.us
Final copies will be distributed to all Conservation Commissions.

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