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Cabin Branch
Stormwater Management
Retrofit Projects
Quail Valley Pond #1
Quail Valley Pond #2
Strawberry Knoll Facility
C...
Today’s Agenda
 Sources of Water on Earth
 Montgomery County background
 What is a Watershed & Runoff?
 Intro to Storm...
Sources of Water

 About 97% is salt water
 About 2% is frozen
 Only 1% is available for drinking water
 Across the co...
Montgomery County, MD
 500 sq. miles
 970,000 people
 Second only to Baltimore City within
Maryland in average people p...
What is a Watershed?
 A watershed is an area
from which the water
above and below ground
drains to the same place.
 Diff...
What is Runoff?
Water that does not soak into the ground becomes
surface runoff. This runoff flows over hard surfaces like...
What is the County doing to
protect our Streams?
 Must meet regulatory requirements
 Federal Clean Water Act permit prog...
MS4 Permit: What is it?
 Montgomery County is responsible for:
• What goes into our storm drain pipes
• What comes out of...
Overall Goals of the Project
 Provide water quality treatment and downstream channel






9

protection to meet MS4 ...
Project Location

Cabin
Branch

10
Quail Valley Pond # 1
SWM Retrofit
Project Overview

11
Drainage Area
 9.24 acre drainage
area to pond
 51% impervious

 Land cover includes
roadway, sidewalks,
manicured
lawn...
Existing Conditions
 Constructed in the early 1980s
 Fully developed drainage area
 Does not provide water quality func...
Existing Quail Valley Pond # 1

View of facility from Centerway Rd

14

Existing substandard riser.

Bottom of facility sh...
Retrofit Design Details
 Grade bottom of pond and eastern bank.

 Create a 3.5’ deep wet pool.
 Remove and replace exis...
Proposed Pond Retrofit

Plan View
16
Proposed Pond Retrofit

Profile

17
Quail Valley Pond # 2
SWM Retrofit
Project Overview

18
Drainage Area
 48.9 acre drainage
area to pond
 24% impervious

19
Existing Conditions
 Constructed in the early 1980s
 Fully developed drainage area
 Dry detention pond constructed in a...
Existing Quail Valley Pond # 2

21
Retrofit Design Details
 Enlarge the storage volume to treat 50% of the

Water Quality Volume (WQv)
 Add a sand berm to ...
Retrofit Design Details
 Install a forebay at the top of the pond to improve

maintenance
 Remove existing risers and re...
Proposed Pond Retrofit

24
Proposed Pond Retrofit

Profile of Proposed Retrofit

Cross-Section of Proposed Retrofit
25
Stormwater Pond Retrofit
During Construction

26
Stormwater Pond Retrofit
Within 1 Year After Construction

27
Stormwater Pond Retrofit
Within 5 Years After Construction

28
Strawberry Knoll
Underground SWM Facility
Project Overview

29
Drainage Area
 20.5 acre drainage
area to facility
 37% impervious

 Land cover includes
roadway, sidewalks,
manicured ...
Existing Site Conditions
 Parcel is owned by the Flower Hill Central Corporation
 Parcel provides open space for Flower ...
Existing Open Space

Location of Proposed SWM Facility.

32

Open space south of proposed facility.

Location of proposed ...
SWM Design Details
 Underground gravity driven treatment system.

 Three components: pretreatment, storage, and
treatmen...
Proposed SWM Design

Plan View
34
Proposed SWM Design

Profile
35
Grass Pavers

UrbanGreen Grass Paver Detail

36
Stormwater Treatment

Vortechs Pretreatment System

Stormfilter System
Underground SWM Facility
During Construction

Storage system being installed

38

Watertight joint being sealed
Quail Valley Pond # 1 Construction Access
 Access from Centerway Road
 Tree removal and grading
 Tree protection where
...
Quail Valley Pond # 2 Construction Access
 Access from Centerway

Road
 Clear width will likely
require tree removal and...
Strawberry Knoll Construction Access
 Access from Strawberry Knoll

Road
 Access will be stabilized to
prevent sediment ...
Construction Access (Example)

During Construction

After Construction
Reforestation


43

Attractive native
trees and shrubs
will be planted
within the project
area
Schedule
 Public meeting to discuss 30% designs 2/11/2014
 60% design – Summer 2014
 90% design – Winter 2014
 Permits...
Questions/Comments?

Darian Copiz, Montgomery County Department of Environmental Protection
240-777-7774 / Darian.Copiz@mo...
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Feb 11 2014 public meeting show

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February 11, 2014 public meeting presentation for three proposed stormwater facility management projects off of Cabin Branch of Great Seneca Creek. (powerpoint file)

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  • Millions have lived without love. No one has lived without water.Turkish businessman, 1998I thought this was hilarious, I got the quote from Jerry’s CD … we do not have to use it.
  • Federal Clean Water ActNPDES: National Pollutant Discharge Elimination System MS4: Municipal Separate Storm Sewer System PermitMS4 Permit sets priorities for all Watershed
  • Transcript of "Feb 11 2014 public meeting show"

    1. 1. Cabin Branch Stormwater Management Retrofit Projects Quail Valley Pond #1 Quail Valley Pond #2 Strawberry Knoll Facility Concept Design Presentation February 11, 2014
    2. 2. 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 Pond Retrofit  Questions/Comments 2
    3. 3. Sources of Water  About 97% is salt water  About 2% is frozen  Only 1% is available for drinking water  Across the country, most potable water is from groundwater  In Maryland, most is from surface water  Potential for greater impacts from runoff in Maryland 3
    4. 4. 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 District of Columbia Impervious: Not allowing water to soak through the ground. 4
    5. 5. 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) 5
    6. 6. 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 6
    7. 7. 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  7
    8. 8. 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 untreated impervious surfaces (4,292 acres = 6.7 square miles). That’s about three times the size of Takoma Park. 8
    9. 9. Overall Goals of the Project  Provide water quality treatment and downstream channel     9 protection to meet MS4 program requirements. Improve ecological value of existing stormwater management facilities. Improve existing landscaping and plant diversity of existing facilities. Upgrade existing facilities to comply with safety and design standards. Utilize existing open space to provide stormwater management.
    10. 10. Project Location Cabin Branch 10
    11. 11. Quail Valley Pond # 1 SWM Retrofit Project Overview 11
    12. 12. Drainage Area  9.24 acre drainage area to pond  51% impervious  Land cover includes roadway, sidewalks, manicured lawns/landscaping. 12
    13. 13. Existing Conditions  Constructed in the early 1980s  Fully developed drainage area  Does not provide water quality functions  High groundwater exists in bottom of facility  Does not meet current safety and design standards (materials and conveyance)  Sinkholes have recently developed in embankment  Maintenance access is inadequate  Minor sediment deposition from upstream erosion 13
    14. 14. Existing Quail Valley Pond # 1 View of facility from Centerway Rd 14 Existing substandard riser. Bottom of facility showing base flow Sinkhole resulting from riser degradation.
    15. 15. Retrofit Design Details  Grade bottom of pond and eastern bank.  Create a 3.5’ deep wet pool.  Remove and replace existing riser and outflow pipe.  Reconstruct portion of existing embankment.  Remove small diameter trees within limits of work.  Provide access path for maintenance.  Re-vegetate pond and plant additional trees. 15
    16. 16. Proposed Pond Retrofit Plan View 16
    17. 17. Proposed Pond Retrofit Profile 17
    18. 18. Quail Valley Pond # 2 SWM Retrofit Project Overview 18
    19. 19. Drainage Area  48.9 acre drainage area to pond  24% impervious 19
    20. 20. Existing Conditions  Constructed in the early 1980s  Fully developed drainage area  Dry detention pond constructed in a stream valley  Very few ecological or water quality benefits  Good condition, but riser is nearing end of service life  Maintenance access is inadequate  Minor sediment deposition from upstream erosion  Degradation and incision of downstream channel 20
    21. 21. Existing Quail Valley Pond # 2 21
    22. 22. Retrofit Design Details  Enlarge the storage volume to treat 50% of the Water Quality Volume (WQv)  Add a sand berm to increase infiltration  Grade an additional storage basin in existing open space adjacent to stream banks  Safely pass larger storms, including the 100-year storm 22
    23. 23. Retrofit Design Details  Install a forebay at the top of the pond to improve maintenance  Remove existing risers and replace with cobble riffle structures  Restore downstream channel using step pools  Revegetate pond with native plants 23
    24. 24. Proposed Pond Retrofit 24
    25. 25. Proposed Pond Retrofit Profile of Proposed Retrofit Cross-Section of Proposed Retrofit 25
    26. 26. Stormwater Pond Retrofit During Construction 26
    27. 27. Stormwater Pond Retrofit Within 1 Year After Construction 27
    28. 28. Stormwater Pond Retrofit Within 5 Years After Construction 28
    29. 29. Strawberry Knoll Underground SWM Facility Project Overview 29
    30. 30. Drainage Area  20.5 acre drainage area to facility  37% impervious  Land cover includes roadway, sidewalks, manicured lawns, open space, and landscaping. 30
    31. 31. Existing Site Conditions  Parcel is owned by the Flower Hill Central Corporation  Parcel provides open space for Flower Hill Community  Two stormdrain systems connect under open space  Flow in existing stormdrain is not treated for Water Quality or Channel Protection  Space is available on site to provide an SWM facility  Site is accessible from Strawberry Knoll Road 31
    32. 32. Existing Open Space Location of Proposed SWM Facility. 32 Open space south of proposed facility. Location of proposed construction and maintenance access. Existing inlet which SWM system will connect to.
    33. 33. SWM Design Details  Underground gravity driven treatment system.  Three components: pretreatment, storage, and treatment.  Pretreatment simplifies and reduces the need for maintenance.  Storage System stores stormwater until filtered.  Filter replaces natural functions depleted with development.  Provide stable vegetated access path for future maintenance. 33
    34. 34. Proposed SWM Design Plan View 34
    35. 35. Proposed SWM Design Profile 35
    36. 36. Grass Pavers UrbanGreen Grass Paver Detail 36
    37. 37. Stormwater Treatment Vortechs Pretreatment System Stormfilter System
    38. 38. Underground SWM Facility During Construction Storage system being installed 38 Watertight joint being sealed
    39. 39. Quail Valley Pond # 1 Construction Access  Access from Centerway Road  Tree removal and grading  Tree protection where needed  Mulch placed on path and removed after construction  Access will be stabilized to prevent sediment transport to Centerway Road 39
    40. 40. Quail Valley Pond # 2 Construction Access  Access from Centerway Road  Clear width will likely require tree removal and grading  Tree protection where needed  Mulch placed on path and removed after construction 40
    41. 41. Strawberry Knoll Construction Access  Access from Strawberry Knoll Road  Access will be stabilized to prevent sediment transport to Strawberry Knoll Road  Curb ramp and grass pavers will be provided at final stages of construction. 41 Location of proposed construction and maintenance access.
    42. 42. Construction Access (Example) During Construction After Construction
    43. 43. Reforestation  43 Attractive native trees and shrubs will be planted within the project area
    44. 44. Schedule  Public meeting to discuss 30% designs 2/11/2014  60% design – Summer 2014  90% design – Winter 2014  Permits issued – Spring 2015  Construction – Summer 2015 44
    45. 45. Questions/Comments? Darian Copiz, Montgomery County Department of Environmental Protection 240-777-7774 / Darian.Copiz@montgomerycountymd.gov www.montgomerycountymd.gov/watershedrestoration Click on “Stream Restoration” and “Stormwater Pond Retrofits” 45
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