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Stormwater Facility Major Projects

The Stormwater Facility Maintenance Program (SWFMP) oversees the maintenance and repair of all stormwater management facilities throughout Montgomery County. In addition to routine maintenance and repair projects, the County regulations allow Water Quality Protection Charge (WQPC) funds to be used for Major Stormwater Maintenance Projects. These funds are used primarily for stormwater facilities that Montgomery County has assumed maintenance responsibility for.

The Department of Environmental Protection is responsible for the Stormwater Facility Maintenance Program.

 

What is a Major Stormwater Maintenance Project?

Major Stormwater Maintenance Projects include:

  • Repair or modification of structural components of a stormwater pond, like the dam embankment, the control structure or the outlet pipe

  • Removing the large accumulation of sediment from a stormwater pond (also known as dredging)

Repairing and improving stormwater management ponds ensures the facilities capture and treat volumes of rainfall runoff generated by impervious surfaces, such as parking lots, roads, and rooftops. When possible the Major Stormwater Maintenance Project will retrofit the existing design of the stormwater facility to improve its stormwater treatment.

 

To learn about the different stormwater management major projects, click the "On this Page" tabs on the upper right.

 

Image of the stormwater diagram

 

Lake Whetstone Dredging

Lake Whetstone is in the heart of Montgomery Village. The Lake was created in the late 1960s by building a dam across Whetstone Run in the Great Seneca subwatershed. It was originally designedf to be a recreational lake and provide stormwater management benefits. The pond dam also serves as a road embankment for Montgomery Village Avenue, and is designated as a significant hazard dam by the Maryland Department of the Environment. The Department of Environmental Protection (DEP) is responsible for structural maintenance of the Lake.

 

 

Over the years, a large amount of sediment has settled on the bottom of the Lake, requiring it to be dreged twice. The last dredging occurred in 1985. Sediment has again built up, forming a delta that negatively impacts water quality. Sediment accumulation is a normal process in stormwater ponds and lakes. However, a significant amout of sediment can affect the water quality treatment processes of the lake and must be removed.

As part of this project, DEP is evaluated:

  • Sediment accumulation for removal

  • Concrete control structures condition and need for repair, and shoreline erosion and need for stream restoration of Whetstone Run tributary.

A potential stream restoration project close to the lake was not included because it won’t be cost effective. After evaluating the condition of the stream reach, and analyzing it via comparison to a similar stream in the region, DEP concluded that:

  • The fine sediment found in the streambed suggests that the stream reach is settling and passing a lot of sediment delivered from upstream areas rather than generating excessive amounts of sediment within the study reach. Repairing the evaluated reach would likely not decrease sediment levels delivered to the lake.

  • Regarding the stream’s steep cut bank in the study reach, according to observations of a characteristically similar stream impacted by urban development, historical data suggests that this is a symptom of urban streams adjusting to deposits that they place in the valley (floodplain). Essentially, the sediment is being swapped between the stream and the flood plain, but the floodplain is still functioning as it should, storing large amounts of sediment. Again, repairing the cut bank in this location at this time won’t help reduce sediment delivered to the lake. In fact, in the short term, repair work may increase sediment transport through the study reach to the lake.

 

Pond Sediment Details:

As part of the sediment removal project, DEP performed a screening level sampling to determine if contaminants could be detected in the dredged material from Lake Whetstone. Three samples were taken from the southeastern end of the Lake where the dredging will take place; and one background sample was taken from a ball field nearby. The following conclusions may be drawn from the sampling results:

  • The results of the sample indicated that elevated levels of Polycyclic Aromatic Hydrocarbons (PAHs) were found in the sediment samples.

  • Concentrations of metals in the sediment of the Lake were reported at elevated levels but similar to the background sample result’s levels.

  • All three sediment samples had levels of fecal coliform bacteria. However, due to the daily variability of the bacterial population counts in water and sediment, these results are inconclusive in determining the bacteria concentration of the dredged material.

Due to the testing results, DEP will dispose of the sediment at a disposal facility permitted to accept the material.

 

Project Facts:

Project Status Design complete, construction planned to start June 1, 2015
Total Drainage Area: 2000 Acres
Total Percent Impervious: 11.5%
Estimate Costs: $2.9 Million
Watershed: Great Seneca
Contact:

DEP Engineer: Julia Liu

Julia.Liu@montgomerycountymd.gov

240-777-7762

Upcoming Public Meeting: None scheduled at this time.

 

Past Public Meetings:

October 2013 meeting material:

Initial Meeting:  

 

Map Location:

Map of the Lake Whetstone stormwater maintenance project.

This map shows the location of Lake Whetstone in shaded yellow dots.

Download a PDF of the map  (PDF, 1.7MB)

 

Site Design Plan:

DEP hires project engineers to prepare Site Design Plans which outline the construction and design or redevelopment of stormwater facilities that have either failed to operate or no longer meet current Stormwater Management standards. The Site Design Plan is done in three stages: 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is complete, construction will begin.

Final Design Plan  (PDF, 12.2MB)

 

 

Gunners Lake

Gunners Lake is located in Germantown, Maryland and has a surface area of approximately 20 acres. The lake was created in late 1985 by building a dam across Gunners Branch in the Great Seneca subwatershed. The pond dam serves as a road embankment for Wisteria Drive, and is designated as a significant hazard dam by Maryland Department of Environment. The Department of Environmental Protection (DEP) is responsible for structural maintenance of the lake.

Over the years, a large amount of sediment has settled on the bottom of the north end of the lake, requiring it to be removed. Sediment accumulation is a normal process in stormwater ponds and lakes. However, a significant amount of sediment can affect the water quality treatment processes of the lake and must be removed. As part of this project, DEP is evaluating the sediment accumulation in the lake for removal, and upgrading the facility to bring it into current stormwater management design standards.

The stormwater lake improvements will help to protect Seneca Creek, which drains to the Potomac River and the Chesapeake Bay.

 

Pond Sediment Details:

As part of the sediment removal project, DEP performed a screening level sampling to determine if contaminants could be detected in the dredged material from Gunners Lake. Three samples were taken from the north end of the Lake where the dredging will take place. The following conclusions may be drawn from the sampling results:

  • The results of the samples indicated that elevated levels of Polycyclic Aromatic Hydrocarbons (PAHs) were found in the sediment samples.

  • Concentrations of three metals (aluminum, chromium and iron) in the Lake sediment were reported at elevated levels.

  • Fecal coliform bacteria was not detected in any of the three samples.

  • Sediment Testing Results

Due to the testing results and the volume of the sediment, DEP has hired a contractor to perform a hydraulic dredge and mechanical sediment dewatering process. The sediment will be disposed of at a facility permitted to accept the material.

 

Project Facts:

Project Status Awaiting Department of Permitting Services Approval
Total Drainage Area: 1233 Acres
Total Percent Impervious: 17.2%
Estimate Costs: $2.89 Million
Watershed: Great Seneca
Contact:

DEP Engineer: Billy Whelan

William.Whelan@montgomerycountymd.gov

240-777-7727

Upcoming Public Meeting

Saturday, December 6, 2014 9:00a.m.

Meet at the outfall structure on the path by Wisteria Dr.

 

Public Meeting:

Past: November 2013

 

Map Location:

Map of the Gunners Lake stormwater maintenance project

This map shows the location of Gunner Lake in shaded yellow dots.

Download a PDF of the map (PDF, 1.9MB)

 

Site Design Plan:

DEP hires project engineers to prepare Site Design Plans which outline the construction and design or redevelopment of stormwater facilities that have either failed to operate or no longer meet current Stormwater Management standards. The Site Design Plan is done in three stages: 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is complete, construction will begin.

90% Design Plan (PDF, 20MB)

 

Chadswood Dry Pond Emergency Repairs

An emergency situation has developed at the Chadswood Regional Stormwater Management Pond Dam located on Cross Laurel Drive between Valley Bend Drive and Blunt Road in Germantown, Maryland. During an inspection of the pond, Montgomery County Department of Environmental Protection (MCDEP) discovered three sink holes in the dam and damage to the pipe going through the dam.

Image of Chadswood Riser

DEP is designing a repair to the dam and replacement of the damaged pipe. Cross Laurel Drive goes across the dam. The County Department of Transportation is monitoring the road and will close the road if necessary. The project is proceeding on a fast track schedule.

Image of Downstream Chadswood

 

Project Facts:

The construction is estimated to begin around November/December 2013.

Project Status Design complete
Total Drainage Area: 323.54 Acres
Total Percent Impervious: 14%
Estimate Costs: TBD
Watershed: Great Seneca Creek
Contact:

DEP Engineer: Gene Gopenko

Gene.Gopenko@montgomerycountymd.gov

240-777-7723

Upcoming Public Meeting:

 

Past Public Meetings:

Monday, October 27, 2014

 

Thursday, October 3, 2013

 

Map Location:

Map of Chadswood dry pond

Download a PDF of the map (PDF, 1.9MB)

 

Site Design Plan:

DEP hires project engineers to prepare Site Design Plans which outline the construction and design or redevelopment of stormwater facilities that have either failed to operate or no longer meet current Stormwater Management standards. The Site Design Plan is done in three stages: 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is complete, construction will begin.

Final Design Plan  (PDF, 17.3MB)


 

Pueblo Road Pond Retrofit

The Pueblo Road Pond is located in a stream valley in the Seneca Creek Watershed approximately 600 feet downstream from Pueblo Road in Gaithersburg.  The pond is the last and most downstream in a sequence of several stormwater management ponds.  The pond is located adjacent to Quince Orchard Manor neighborhood.

Stormwater management ponds in the County are routinely inspected for function and safety. An inspection found that several components of the Pueblo Road Pond were in need of repair. An engineering consultant was hired by DEP to perform an evaluation, and subsequently recommended repair work.  The consultant report indicated that the pond is not in conformance with current standards for larger storms. Additionally, the consultant indicated that the dam is in need of repair.

The consultant determined that the pond should be retrofitted to provide the stormwater control for the contributing drainage area.  The new dam embankment will be constructed to meet the current safety standards.

A new concrete weir wall (this regulates water release) structure will be employed. Because of space constraints and the existence of an 8" sewer line through the dam, the weir is designed as a labyrinth weir wall structure in order to maximize the weir wall length while minimizing the footprint of the structure.

In addition, the existing sewer line in the affected area will be replaced with a new 8" ductile iron pipe.  The pipe will be encased in a 21" reinforced concrete pipe sleeve under the dam to protect the pipe and for easy access for maintenance purposes.

 

Project Status In Design
Total Drainage Area: 225.01 Acres
Total Percent Impervious: 26%
Estimate Costs: ---
Watershed: Seneca Creek
Contact:

DEP Engineer: Gene Gopenko

Gene.Gopenko@montgomerycountymd.gov

240-777-7723

Upcoming Public Meeting: ----

 

Public Meeting:

Past: June 21, 2007
Quince Orchard Library

 

Map Location:

Map of Pueblo Road Pond Retrofit

Download a PDF of the map (PDF, 329KB)

 

Site Design Plan:

DEP hires project engineers to prepare Site Design Plans which outline the construction and design or redevelopment of stormwater facilities that have either failed to operate or no longer meet current Stormwater Management standards. The Site Design Plan is done in three stages: 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is complete, construction will begin.

90% Design Plan  (PDF, 14.9MB)

 

Completed Projects

 

Montgomery Auto Park Regional Pond

Montgomery Auto Park Pond, owned by Montgomery County, is formed by a 28-ft high earth embankment dam located off Briggs Chaney Road in Silver Spring, MD and adjacent to Inter-County Connector (ICC) (MD-200). The dam is currently designated as a high hazard dam by the Maryland Department of the Environment (MDE). The dam was originally designed to provide stormwater management control for a 238-acre watershed.

In 2006, a routine inspection revealed a seepage problem near the toe of the dam. The MDE Dam Safety Division declared the dam unsafe and ordered the repairs. The ICC recent construction diverted a large portion of the flow away from the pond. DEP's repair and retrofit work included:

Image of Montgomery Autopark Regional Dam Riser
  • Lowering of the dam height;

  • Widening of the emergency spillway;

  • Modifications to the concrete control structure;

  • Repairing the seepage in the dam; and

  • Removing sediment from the pond bottom.

The repairs are completed.

The retrofitted pond will provide stormwater control for the residential and commercial areas draining to the pond. The Montgomery Auto Park Pond also helps to protect the Anacostia River, which drains to the Potomac River and the Chesapeake Bay.

 

Map Location:

 

Map of the location of the Montgomery Autopark stormwater facility.

 

This map shows Montgomery Autopark Regional Dam. The location of the pond is shaded in yellow along MD-200.

Download a PDF of the map (298KB)

 

Site Design Plan:

Site Design Plans are printed drawings and details that the project engineers prepare to outline the construction plan for design or redevelopment of a stormwater facility that has either failed to operate or no longer meets Stormwater Management standards. The Site Design Plan is done in three stages; 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is completed, construction begins.

The 100% or Final Design Plan was approved on March 03, 2013.  Construction is complete.

 

Brookville Bus Depot

This project evaluated existing onsite stormwater management facilities and their effectiveness at controlling runoff from the Brookville Bus Depot.Image of Brookville Bus Depot

DEP's improvements included:

  • Installation of new underground stormwater management facilities;

  • Modification of existing stormwater facilities and drainage structures;

  • Removal of sediment and retrofit of existing stormwater pond

The new stormwater improvements will help to protect Rock Creek, which drains to the Potomac River and the Chesapeake Bay.

 

Project Schedule:

Construction is complete.

 

Map Location:

Map of the location of the Brookville Bus Depot stormwater maintenance project.

This map shows the Brookville Bus Depot. The location of the pond is indicated by the circle on the left hand side of the image.

Download a PDF of the map (182KB)

 

Site Design Plan:

Site Design Plans are printed drawings and details that the project engineers prepare to outline the construction plan for design or redevelopment of a stormwater facility that has either failed to operate or no longer meets Stormwater Management standards. The Site Design Plan is done in three stages; 30% Design Stage, 60% Design Stage and 100% or Final Design Stage. Once the Final design is completed, construction begins.

The 100% or Final Design Plan was approved on March 03, 2013. Construction is complete.