FirstLight Power Shoreline Management Manual Sustainable Shoreline Designs: From Long Island to Lake Erie Webinar Series

Transcription

1 FirstLight Power Shoreline Management Manual Sustainable Shoreline Designs: From Long Island to Lake Erie Webinar Series Presented by Jason Williams, PLA, NCI February 19, 2017 Introduction Lakes (impoundments) created by the construction of hydroelectric facilities along the Housatonic River in the early 1900 s. Over the subsequent century the lands surrounding the impoundments have been developed with a recent increase in development and water related recreational activities Facilities are now owned by FirstLight Hydro Generating Company under a license from the Federal Energy Regulatory Commission and are required to develop Shoreline Management Plans (SMP) as part of their relicensing requirements. As part of their SMP, FirstLight was required to develop a Shoreline Management Manual for all of its impoundments The Shoreline Management Manual is a guide for FirstLight and property owners to effectively preserve, establish, enhance and maintain successful shoreline/ bank stabilization and vegetated buffer zones The Manual: Describes how to plan for and establish stable shorelines and vegetated buffers Explores alternative shoreline protective measures Identifies appropriate plant species and densities

2 What are Vegetated Buffers ECOTONE The shoreline of a lake is the single most important aspect of lake ecology. It is the interface between the water and surrounding landscape. According to the U.S. Environmental Protection Agency 2009 National Lakes Assessment, poor lakeshore habitat is the biggest problem in the nations lakes. Degraded biological health is three times more likely in lakes with poor lakeshore habitat. 4 Upland Zone This buffer zone exists above the seasonal high water table in a drier environment and is the edge leading from the riparian zone to the forest. It is dominated by large canopy trees, provides full shade, and limited understory 3 Floodplain Zone Is typically a native meadow with successional shrub growth and/or forested floodplain and dominated by upland herbaceous plants that create a filter strip Primary function is initial protection of the lake from overland flow of nonpoint source pollutants (fertilizers and pesticides) Properly designed native tall grass and herbaceous buffer strip plantings can provide quality habitat for several upland wildlife species 2 Riparian Zone Extends inland from the littoral zone for a minimum of 10 feet up to several hundred feet depending on soil type, topography, and historical or current land use Provides a natural transitional area between terrestrial and aquatic environments Composition and characteristics of vegetation in this zone are similar to that of the adjacent upland floodplain/ forested areas, yet it functions as the outer edge of a lake s transition to the watershed that supports it 1 Littoral Zone Begins in the lake at the depth to which sunlight penetrates the lakebed Habitat for both aquatic and terrestrial organisms Shoreline vegetation provides shade and detritus which assists in anchoring large natural woody debris at the water s edge This zone of transition is a key ecotone that contains aquatic plants that absorb natural wind-driven wave energy and provide shoreline soil stabilization Shallow water ecotone environment where the majority of both plant and animal life interact Importance of Vegetated Buffers Collecting, treating, and filtering polluted stormwater runoff Stabilizing shoreline soil and slope Reducing maintenance needs and costs on lakefront properties Providing food and shelter for fish, reptiles, birds, and insects. Providing privacy for lakefront residences thus increasing property values

3 Existing Shoreline of Impoundment Goal: Naturalized Vegetated Buffer General Considerations for Natural Vegetated Buffers Wind and Wave Exposure Soil Types (Composition, Structure, ph) Groundwater Interaction Degree of Slope Sunlight Exposure

4 Creating A Natural Vegetated Buffer No Mow Year - 1 Year - 10 Natural buffer No-Mow zone with grasses establishing Natural buffer No-Mow zone with shrubs and small trees establishing Year - 20 Natural buffer No-Mow zone with larger established trees, shrubs, and herbaceous vegetation Creating A Natural Vegetated Buffer Enhanced No Mow Enhanced No Mow Enhanced buffer No-Mow zone and native supplemented planting Landscaped Buffer Landscaped buffer of formalized native plantings

5 Stormwater Management within Vegetated Buffers Stormwater runoff with vegetated buffer Typical infiltration gallery for clean roof run off What is shoreline stabilization To successfully implement shoreline protection measures, it is important to consider all available options. In many cases, site-specific conditions may determine that a matrix of methods is the best choice for a site. Site conditions such as accessibility to a site for machinery or materials, slopes, soils, existing seawalls or retaining walls, and costs may lead to different options. Structural: Use of inert structural materials (i.e. concrete, boulders, gabions, stone blocks) to reinforce soil and stabilize banks. Biotechnical: Combines the use of living plant material and inert structural materials (i.e. boulders, woody debris, coir logs) to reinforce soil and stabilize banks. Bioengineering: Use of living plant material as the primary structural component to reinforce soil and stabilize banks.

6 Structural Stabilization Structural Shoreline Stabilization Most Expensive Requires Professional Engineer Wave and Scour Impacts Groundwater and Ice Factors Year Life Span

7 Structural Stabilization Measures Structural Stabilization Measures Severe Bank Erosion Stacked Boulder Revetment

8 Structural Stabilization Measures C.I.P concrete form liner wall with boulder revetment Pedestrian access that is able to flood Existing Stabilization Measures Fail Loss of Littoral Vegetation Loss of Littoral Habitat (Scour) Groundwater and Ice Factors Short Life Span Wave energy that is deflected off a seawall can cause erosion (scour) and severely impact fish and wildlife habitat.

9 Potential Structural Stabilization Measures Natural Boulder Revetment Created Littoral Zone/ Relocation of Seawall Typical cross section of dry staked boulder seawall Structural Shoreline Stabilization

10 Biotechnical Stabilization Biotechnical Stabilization Measures Combination of Soft and Hard Treatments Use in moderate wave areas Natural Boulders, Tubelings, Live Stakes, Live Fascines Lowbush Blueberry Sod

11 Biotechnical Stabilization Measures Brush Mattress & Log Cribbing Brush Mattresses Bioengineering Shoreline Stabilization Measures Least Expensive May Require Professional Engineer Wave and Scour Impacts Use of Natural Boulders mixed with Plantings Removed Seawall Bioengineering Biotechnical

12 Biotechnical Stabilization Measures During Construction Boulders with Plantings Post Stabilization Biotechnical Stabilization Measures

13 Bioengineering Stabilization Bioengineering Stabilization Measures Least Expensive Soft Treatment Measures Quiescent Waters (Protected Coves) Live Stakes, Live Fascines, Coir Logs Live Stakes

14 Bioengineering Stabilization Measures Shoreline Stabilization Measures Compared

15 Alternative Shoreline Protection Measures Live Fascines Brush Matting Rip-Rap/ Boulder Slope Live Staking and Boulders Soil Wraps Vegetated Gabions Log Crib Wall Homeowner Decision Tree

16 Plant Lists and Spacing Requirements Legend Vegetation defined Nurseries Plant Indicator Status Plant Lists and Spacing Requirements

17 Glossary and References Glossary References Contributors Before and After Renderings Contributors

18 Contacts & Questions Jason Williams, PLA Lead Landscape Architect Milone & MacBroom, Inc. Cheshire, CT Tel: