Bedfordshire Stormwater Pond Retrofit & Stream Restoration Don - - PowerPoint PPT Presentation

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Bedfordshire Stormwater Pond Retrofit & Stream Restoration Don - - PowerPoint PPT Presentation

Oct 29, 2023 363 likes •769 views

Bedfordshire Stormwater Pond Retrofit & Stream Restoration Don Dorsey, Watershed Planner Mike Lichty, Engineer Montgomery County Department of Environmental Protection Watershed Management Division Pond Sequence Number 738 Todays Agenda

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Bedfordshire Stormwater Pond Retrofit & Stream Restoration

Don Dorsey, Watershed Planner Mike Lichty, Engineer Montgomery County Department of Environmental Protection Watershed Management Division Pond Sequence Number 738

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Today’s Agenda

 Sources of Water on Earth  Montgomery County background  What is a Watershed & Runoff?  Intro to Stormwater  What the County is Doing to Protect Our Streams  Goals of the Project  Proposed Retrofit of the Pond  Trees proposed to be saved and removed  Health of those trees to be removed  Proposed Restoration of Bedfordshire Tributary  Questions/Comments

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Sources of Water

 About 97% is salt water  About 2% is frozen  Only 1% is available for drinking water

 95% from groundwater across the Country  32% from groundwater, 68% from surface water in Maryland

Potential for greater impacts from runoff in Maryland

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Montgomery County, MD

 500 sq. miles  970,000 people

 Second only to Baltimore City within

Maryland in average people per square mile

 184 languages spoken

 About 12% impervious surface overall

 About the size of Washington DC

 Over 1,500 miles of streams  Two major river basins:

 Potomac  Patuxent

 Eight local watersheds

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District of Columbia

Impervious: Not allowing water to soak through the ground.

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What is a Watershed?

 A watershed is an area

from which the water above and below ground drains to the same place.

 Different scales of

watersheds:

 Chesapeake Bay  Eight local watersheds  Neighborhood (to a storm

drain)

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What is Runoff?

Water that does not soak into the ground becomes surface runoff. This runoff flows over hard surfaces like rooftops, driveways and parking lots collecting potential contaminants and flows:

  • Directly into streams
  • Into storm drain pipes, eventually leading to

streams

  • Into stormwater management facilities, then

streams

Two Major Issues: Volume/Timing of Runoff Water Quality

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What is the County doing to protect our Streams?

 Must meet regulatory requirements

 Federal Clean Water Act permit program  MS4 = Municipal Separate Storm Sewer System

 Applies to all large and medium Maryland jurisdictions  County programs

 Restore our streams and watersheds

 Add runoff management

 Meet water quality protection goals

 Reduce pollutants getting into our streams

 Educate and engage all stakeholders

 Individual actions make a difference

 Focus on watersheds showing greatest impacts

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MS4 permit, what is it?

 Montgomery County is responsible for:

  • What goes into our storm drain pipes
  • What comes out of them
  • What flows into the streams

 Requires additional stormwater management for 20

percent of impervious surfaces (4,292 acres = 6.7 square miles). That’s about three times the size of Takoma Park.

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Overall Goals of the Project

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  • Improve efficiency of five (5) stormwater management

(SWM) facilities in the Watts Branch watershed

Maximize SWM facility storage volume with emphasis on meeting 1) channel protection (CPv) and 2) water quality (WQv)

Obtain compliance by meeting current safety standards

Improve access for routine maintenance

  • Improve stream stability and habitat of

two (2) tributaries in the Watts Branch watershed

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Goals of the Project

 Capture more “peak‐flow” runoff from Impervious

Surfaces (Rooftops/Driveways/etc.) within the Stormwater Pond, also called Channel Protection Volume (Cpv)

 Flows are evaluated to ensure no upstream houses are flooded

 Create a Permanent Pool to Capture Nutrients

 Aquatic plants within and along the perimeter of the permanent

pool will help absorb nutrients and provide a balanced aquatic ecosystem.

 May Attract Red Winged Black Birds  Aquatic ecosystem will have a balance of prey (mosquitoes) vs. predator

species.  Referred to as Water Quality Volume (WQv)

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  • Non‐Biting Midge
  • Diving Beetle
  • Damselfly Larvae
  • Backswimmers
  • Water Scorpion
  • Dragonfly Nymph
  • Phantom Midge
  • Water Strider
  • Swallows, Adult Dragonflies,

Frogs

Mosquito Predators

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Stormwater Management Approach

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Proposed Pond Design

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  • Grade pond to provide full channel protection and

partial water quality requirement volumes

  • Install principal spillway and riser
  • Convert dry pond to wet pond and provide safety bench

around interior

  • Provide pond access for maintenance

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SWM Retrofit ~ Bedfordshire Pond

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Stormwater Pond Retrofit ~ During Construction

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Stormwater Pond Retrofit ~ Within 1 Year After Construction

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Stormwater Pond Retrofit ~ Within 5 Year After Construction

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Ecological Restoration

  • Ecological restoration

 process of assisting the recovery

  • f an ecosystem that has been

degraded, damaged, or destroyed

  • Stream restoration

 unable to ecologically recover from a degraded habitat  threat to infrastructure

  • Over‐arching goal for stream restoration

 enable degraded streams to support more diverse and vibrant

biological communities

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Goals of Stream Restoration

  • Improve aquatic and terrestrial habitat
  • Reduce stream channel bank and

bed erosion

  • Protect infrastructure and utilities
  • Reconnect stream to floodplain
  • Enhance riparian buffer and

create/improve wetlands

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Evaluating the Project Goals – Restoration Monitoring

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  • County monitoring to evaluate

whether project goals are achieved

  • County partnership with Audubon

Society – using local residents’ participation in monitoring efforts

  • County restoration monitoring –

salamanders and aquatic insects

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Urban and Suburban Streams

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Land use changes in a watershed and along a stream corridor system , such as an increase in paved area, can results in impacts to stream structure and function.

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Restoration Approach – Bedfordshire Tributary

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  • Habitat enhancement

 riffle/pool complex  riparian cover – shading and avian habitat  diverse and native plant communities, floodplain

forested wetlands and vernal pools

  • Stabilization channel bed and banks

 raising channel invert

and minimizing bank height

  • Increase Floodplain function

 reconnecting to floodplain  sediment and nutrient trapping  hydrologic retention

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Restoration – Before and After Instream Habitat Enhancement

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Restoration – Before and After Instream Habitat Enhancement

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Restoration – Before and After Floodplain Reconnection

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Restoration Approach – Bedfordshire Tributary

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Restoration Approach – Bedfordshire Tributary

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Restoration Approach – Bedfordshire Tributary

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Restoration Approach – Bedfordshire Tributary

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Restoration Approach – Bedfordshire Tributary

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Conceptual Restoration Approach – Bedfordshire Tributary

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Conceptual Restoration Approach – Bedfordshire Tributary

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Conceptual Restoration Approach – Bedfordshire Tributary

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Stream Restoration – During Construction

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Stream Restoration – Immediately Following Construction

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Stream Restoration – 1+ Year After Construction

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Work Completed to Date

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  • Site Survey – complete
  • Natural Resources Inventory and Forest

Stand Delineation – complete

  • Forest Conservation Plan – under

development

  • 60% design – complete, seeking input
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Schedule

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Bedfordshire Pond and Tributary

  • Public Meeting 12/4/13
  • 60% design submitted Oct 2013
  • 90% design March 2014
  • Permits issued Summer 2014
  • Construction Fall 2014/Winter 2015
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Questions/Comments?

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Don Dorsey 240‐777‐7712

donald.dorsey@montgomerycountymd.gov www.montgomerycountymd.gov/watershedrestoration Click on ‐‐>Stormwater Pond Retrofits