Dredging Children’s Pond to Restore Water Quality in Strawbridge Lake

Sedimentation in Children’s Pond, which is located in Strawbridge Lake park, was negatively impacting the water quality Strawbridge Lake. In order to restore the pond and reduce impacts to Strawbridge Lake, the Moorestown Township Council awarded contracts to Princeton Hydro for the dredging and cleanup of the Children's Pond.

Strawbridge Lake is located in Moorestown Township in Burlington County, New Jersey with portions of the watershed also extending into Mount Laurel and Evesham Townships. This 33-acre, tri-basin lake is a result of the impoundment of the confluence of Hooten Creek and the North Branch of the Pennsauken Creek that dates back to the 1920s.

Image by NJ.govThe lake receives surface runoff through Hooten Creek to the Upper and Middle Basins and the Lower Basin receives runoff from the headwaters of the North Branch of Pennsauken Creek. The lake then discharges back into another section of the North Branch Pennsauken Creek, which then flows into the Delaware River.

The watershed area that drains into the Strawbridge Lake is made up of an intricate mix of land uses: agriculture, new and mature residential subdivisions, office parks, major highways, retail stores, and large industrial complexes. The lake and the park area that surrounds it are heavily used for a variety of recreational activities.

Children’s Pond, which is located in Strawbridge Lake Park, is a popular fishing spot in the community. The pond initially functions as a wetland and drains from the northern portion of the watershed. Sedimentation—the naturally occurring process of the deposition and accumulation of both organic and inorganic matter in the bottom and/or banks of waterbodies—had significantly reduced the mean pond depth, thereby reducing the pond’s aesthetic appeal, impairing the fishery, contributing to eutrophication, and impacting the water quality of Strawbridge Lake. Sedimentation can also lead to contamination that poses a threat to aquatic plant and wildlife.

The dredging of Children’s Pond was identified by Princeton Hydro’s Lake and Watershed Management Plan and presented to the Moorestown Township Council’s environmental committee as one of a number of immediate actions needed in order to restore the pond, preserve the health of the watershed, and reduce impacts to Strawbridge Lake. Dredging, often used as an efficient solution for sediment removal, can expeditiously restore the waterway to its original depth and condition while also removing dead vegetation, pollutants, excess nutrients, and trash that may have accumulated.

Moorestown Township Council awarded contracts to Princeton Hydro for the dredging and cleanup of the Children’s Pond, which was an important part of the previously mentioned Watershed Management Plan for Strawbridge Lake.

Before the dredging could begin, a variety of surveys, field investigations, and data collection activities took place at the project site. A bathymetric survey is a critical component of any dredging project because it measures the depth of a waterbody, as well as maps the underwater features of a waterbody.

Due to the small area and shallow depths of Children’s Pond, the survey was conducted using a calibrated sounding rod and a Trimble GPS unit. The calibrated sounding rod was lowered into the water until it reached the top of the accumulated sediment. The location of the sample point and the water depth was then recorded with the GPS unit. Next, the pole was pushed down into the sediment until the point of refusal, and the bottom of sediment elevation was also recorded with the GPS unit. Data was collected from shoreline to shoreline at 25-foot transect intervals.

The data collected via the bathymetric survey, as well as the site survey, field investigations, and soil analysis, was used to shape the project’s engineering design and construction plans.

Before the dredging commenced, Princeton Hydro conducted a bathymetric survey to understand the depth and underwater features of a water body.

With the data collection process complete, Princeton Hydro was able to finalize the engineering plans and obtain all necessary permits for the project. Once the project commenced, Princeton Hydro oversaw the construction process and documented the project’s progress through Daily Field Reports (DFRs).

DFRs act as a living record of the project and provide the project’s key stakeholders with full details of the team’s daily performance and productivity, including arrival and departure times, the weather and temperature, equipment utilized on-site that day, a description of the work completed, and photographs of the work in progress.

This photo from the DFR on March 2, 2020 documents the beginning of excavation work in Children’s Pond:

This photo from the DFR on April 16, 2020 shows grading being completed on the west side of Children’s Pond: 

This photo from the DFR on April 20, 2020 documents the continuation (and near completion) of the excavation and grading work:

Princeton Hydro provides construction oversight services to private, public, and nonprofit clients for a variety of ecosystem restoration, water resource, and geotechnical projects across the Northeast. For more information, go here. And, to get an inside look at all that construction oversight entails, check out our blog:

A Day in the Life of a Construction Oversight Engineer

WATCH: NYSFOLA Hosts Free Lake Management Webinar Series

The New York State Federation of Lake Associations (NYSFOLA), in collaboration with Syracuse University Environmental Finance Center, hosted a four-part, educational webinar series on a variety of topics related to lake management. The goal of the webinar series was to bring together people involved with New York’s lake associations, as well as local government leaders to discuss management tips, understand more about their lakes and watersheds, and explore strategies around improving and protecting New York lakes.

The series concluded on July 23, 2020 with a webinar lead by Chris L. Mikolajczyk, CLM, Senior Project Manager, Aquatics of Princeton Hydro, and Jim Cunningham, NYSFOLA Board Member and the Town of Nelson, NY Supervisor.

In the webinar, titled, “Working with Local Government to Improve Lakes and Communities,” Chris presents a unique initiative lead by the Borough of Ringwood, which became the first municipality in the state of New Jersey to take a regional approach to private lake management through a public-private partnership (PPP) with four lake associations.

Chris provides an overview of The Borough of Ringwood, home to several public and private lakes, which took an active role in the management of its natural resources within multiple watersheds. He explains how the project came together and illustrates why a comprehensive, integrated approach to watershed and lake management is an incredibly important strategy to improve water quality for millions of people and reduce potential future incidents of aquatic invasive species and harmful algal blooms.

During Jim’s portion of the presentation, he discusses the role of local government in lake management and provides examples from projects and initiatives in Madison County, New York. To watch the recording of this webinar, click here.

The webinar series also included presentations about choosing the right liability insurance for a nonprofit organization; turning resource management-related conflicts into opportunities; and understanding lake science and water quality management. To access all of the webinars in the series, go here.

The New York State Federation of Lake Associations, Inc. was founded in 1983 by a coalition of lake associations concerned about water quality, invasive species, and other issues facing New York’s lakes. Today, more than 200 lake associations across the state are members of the only statewide voice for lakes and lake associations. NYSFOLA also has corporate members and individual members who support our efforts.

Princeton Hydro is the industry leader in lake restoration and watershed management. We have conducted diagnostic studies and have developed management and restoration plans for over 300 lakes and watersheds throughout the country. This has included work for public and private recreational lakes, major water supply reservoirs, and watershed management initiatives conducted as part of USEPA and/or state-funded programs. For more information about our lake management services, click here.

Dam Safety Recommendations for Tropical Storm Isaias

Tropical Storm Isaias Forecast. Source: NOAA

We, at Princeton Hydro, care for the health, safety, and well-being of our clients. We are tracking Tropical Storm Isaias closely as it heads up the East Coast, and the most recent precipitation forecast by NOAA is calling for a significant amount of rainfall in the NJ, PA, MD, NY region. Please be advised that the predicted precipitation could potentially pose a risk to your dam, pond, basin, or other structures.

For our clients who own and/or operate dams, levees, and other flood management structures, please take the following precautions, as adopted from a statement issued today by NJDEP Division of Dam Safety and Flood Engineering (see below), seriously:

  • For high/significant hazard dams, check your Emergency Action Plan to ensure that all contacts for emergency notification and emergency resources (engineers, contractors, supplies, etc.) are up to date.
  • Please refresh yourself regarding the dam owner’s responsibilities in the event of an emergency.
  • Please monitor your dam before, during, and after the storm event and report any concerns to your state Dam Safety office.
  • Prior to the storm, please take precautions to ensure that all spillways are clear of debris and that floating objects (boats, floating docks, etc.) which could block a spillway during high flow events are secured, where possible.
  • If you discover that a potential emergency condition exists at the dam, you should immediately contact your state Dam Safety office and the state emergency hotline. You must also contact your engineer, as well as implement your emergency action plan.
  • If your dam has any known vulnerabilities that you wish to discuss in advance of the storm, we recommend that you first contact your engineer. No modifications should be made to the dam without approval from your state Dam Safety office.

If you are a Princeton Hydro client and we provide inspection services to your dam, please reach President Geoffrey Goll, P.E. directly if you have any issues and/or concerns at 908-237-5660 ext. 103 or ggoll@princetonhydro.com. Even if it is after hours and you are concerned about the condition of your dam during this storm event, please do call Geoff directly. Safety is our priority and will do our best to assist you immediately.


State Dam Safety & Emergency Hotline Phone Numbers:

New Jersey:

  • NJDEP Division of Dam Safety and Flood Engineering: 609-984-0859
  • NJDEP Emergency Hotline 1-877-WARNDEP (1-877-927-6337)

New York:

  • NYSDEC, Division of Water, Bureau of Flood Protection and Dam Safety: 518-402-8185

Pennsylvania:

  • PADEP, Bureau of Waterways Engineering and Wetlands, Division of Dam Safety: 717-787-3411
  • PADEP Emergency Hotline: 1-800-541-2050

Maryland:

  • MDE, Water and Science Administration, Dam Safety Division: 410-537-3538
  • MDE’s Emergency Response Division: (866) 633-4686

Connecticut:

  • CT DEEP, Dam Safety Regulatory Program: 860-424-3706
  • DEEP’s Emergency Response Unit: 866-DEP-SPIL (866-337-7745) or 860-424-3338

***IMPORTANT MESSAGE FROM NJDEP***

DAM SAFETY PRECAUTIONS DURING TROPICAL STORM ISAIAS
POSTED: AUGUST 3,  2020 at 9:30 AM

 

This message is from the NJDEP, Division of Dam Safety & Flood Engineering. Based on weather forecasts, it has been determined that the potential for a significant rainfall event exists in the area of your dam. At this time, we are reminding high/significant hazard dam owners to check your Emergency Action Plan to ensure that all contacts for emergency notification and emergency resources (engineers, contractors, supplies, etc.) are up to date. Please also take a moment to refresh yourself regarding the dam owner’s responsibilities in the event of an emergency.

 

Please monitor your dam before, during, and after the storm event and report any concerns to this office. Prior to the storm, please take precautions to ensure that all spillways are clear of debris and that floating objects (boats, floating docks, etc.) which could block a spillway during high flow events are secured, where possible. If you discover that a potential emergency condition exists at the dam, you should immediately contact this office and our 24-Hour DEP Hotline at 1-877-WARNDEP (1-877-927-6337). You must also contact your engineer, as well as implement your emergency action plan.

 

If your dam has any known vulnerabilities that you wish to discuss in advance of the storm, we recommend that you first contact your engineer. You may also contact our office at the number below. No modifications should be made to the dam without approval from this office.

 

Please also be advised that the Division of Dam Safety and Flood Engineering does NOT recommend or require the lowering of impoundments prior to, during, or immediately following a storm event unless the integrity of the dam is in question. If a dam owner chooses to lower an impoundment for any reason, we encourage them to coordinate with local and county emergency management officials to ensure that any increased flow as a result of the lowering does not create flooding conditions downstream of the dam. The dam owner must also coordinate with the Division of Freshwater Fisheries (908-236-2118). A lake lowering permit (issued by Division of Freshwater Fisheries) is usually required prior to lowering.

 

Division of Dam Safety & Flood Engineering
NJ Department of Environmental Protection
609-984-0859

 

Click here for more information about Tropical Storm Isaias, visit NOAA’s National Hurricane Center and Central Pacific Hurricane Center.