Metropolitan Washington Council of Governments and DEP receive joint BUBBA Award for innovation!

University Blvd wet pond with solar powered CMAC control panel March 16, 2017

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First, what exactly is a “BUBBA Award”? BUBBA is an abbreviation for Best Urban Best Management Practices in the Bay. Administered by the Chesapeake Stormwater Network, these annual awards recognize stormwater best management practices (or “BMPs”), such as rain gardens and green roofs, installed in the Chesapeake Bay watershed.

Montgomery County and its partners are constantly working to improve stormwater management and meet water quality improvement goals, and when the County’s Department of Environmental Protection (MCDEP) signed on to a multi-jurisdictional project with Metropolitan Washington Council of Governments (MWCOG), they were looking to do just that.

MWCOG was awarded a grant from the National Fish and Wildlife Foundation (NFWF) to demonstrate the use of smart, integrated stormwater management systems in 2015. With major support from the Anacostia Watershed Restoration Partnership and the Maryland Department of Natural Resources, MCCOG worked with MCDEP to install a creative and cost-effective device on a pond on University Boulevard that would greatly enhance water quality treatment. The innovative technology called Continuous Monitoring and Adaptive Control (CMAC), designed by a stormwater infrastructure company called Opti, represents a new and unique approach to managing stormwater. The goal of this project was to use solar power and weather data to anticipate heavy rainfall, so a stormwater management pond can effectively retain water to reduce erosion and pollution issues downstream.

How it works:

Creating a CMAC retrofit for this pond involved installing solar panels and water level sensors to adaptively control new pond outlet valves. The retrofit also utilized cloud-based software, connecting real-time forecast information from the National Weather Service with the CMAC equipment to determine the timing and expected volume of incoming storm events.

In advance of a storm, the outlet valves close, which allows only stream baseflow to be released. Thus, the pond can retain more runoff volume during and after a storm. After the defined storm’s retention period is over, the software sends a signal to open the valves and release the accumulated water downstream. The pond automatically draws down to create available storage space if another event is forecasted within the retention period. Prior to utilizing CMAC, the pond would continue to collect runoff storm after storm until reaching full capacity and eventually flowing over the pond riser, releasing increased volume and nutrients into the stream.

University Blvd wet pond with solar powered CMAC control panel

What does this all mean?

The innovative design and forecast-based active control of the outlet valves essentially redesigns the pond allowing it to proactively adjust capacity for a given storm or series of storms. This reduces the risk of the pond exceeding capacity, and greatly reduces the amount of polluted runoff that reaches the stream. By utilizing the cloud-based software and optimizing the pond’s performance for a wide range of actual, real-time rainfall events, the County is able to better achieve its water quality goals and also save taxpayer dollars by eliminating the potential need for future excavation to increase water storage.

is able to better achieve its water quality goals and also save taxpayer dollars by eliminating the potential need for future excavation to increase water quality volume.

We monitored the design over twelve months – and the results are in:

Twelve storm events were recorded that resulted in a total of 16.4 million gallons of runoff being collected. Runoff volume recorded downstream of the pond was reduced by 67% compared to runoff released prior to installing the CMAC retrofit technology.
Two 0.3” rainfall events were analyzed and compared for the pre- and post-retrofit pond. When comparing the discharge of total suspended solids (TSS or sediment) for both storms, the pond discharged 72% less TSS (pollution or sediment) downstream to Sligo Creek with the CMAC retrofit than without the device. A significant win for Sligo Creek!
Finally, analysis of five specific rainfall events from March to July 2016 revealed that with the CMAC retrofit, nitrate and TSS removal percentages surpassed the State of Maryland’s stormwater credit removal efficiency, benefiting the water quality of Sligo Creek.