NetTech™ System Traps Pollutants from Wicomico River

Salisbury, Maryland

Highlights

Engineering

Drainage Protection Systems

Stockton, California

The Problem

When the City of Salisbury decided to make an effort to clean-up the trash and debris flowing into the Wicomico River from the adjacent contributing watershed, they chose Oldcastle Stormwater’s NetTech™ gross pollutant traps (GPT) and FloGard Plus catch basin insert filters using a community development block grant. In February 2011, Drainage Protection Systems (DPS), a division of Oldcastle, installed a 24” circular GPT, attaching it to an existing 24” stormwater outfall pipe beneath the Division Street Bridge which is adjacent to the city’s riverwalk. Then in September 2011, a 36” circular GPT was installed on a nearby outfall pipe. The NetTech device will capture trash and debris from the outfall and contain the contents until the city’s maintenance crews pick-up and dispose of the debris.
Once emptied, the netting device is reattached and the process begins anew. The NetTech, an end-of-pipe treatment device, was selected by the city due to the conspicuous location of the outfalls. Not only is the location highly visible by local residents and adjacent property owners, thereby providing an immediate showcase of the captured debris, it also allows appropriate maintenance accessibility for debris collection and disposal.

The Design

The timing of the tidal-influenced Wicomico River had to be accounted for during installation due to the outfall pipe being partially submerged during high tide. Additionally, the upstream storm sewer system maintained a constant runoff through the pipe network, which had to be temporarily dewatered during the installation sequence.
DPS accomplished this through the use of sandbags and a sump pump in the adjacent upstream manhole, thereby providing for a relatively dry installation environment. Furthermore, access for the installation had to be considered due to the river’s proximity to the outfall. The city provided a boat to assist with the installation along the riverwalk, which was needed in conjunction with DPS’s boom-lift vehicle. Traffic was controlled along the Division Street Bridge during installation by the city, while DPS provided power access through a mobile generator which was necessary for properly securing each NetTech device to the outfall pipe. Total installation time took about four hours per unit.

The Solution

The two NetTech units had an immediate impact by drastically reducing the amount of trash and debris deposited into the Wicomico River, thereby providing an enhancement to the city’s river beautification project. These installations were the first two completed portions of the city’s overall stormwater master plan. In May 2012, the city contracted with DPS to install 30 FloGard Plus catch basin insert filters within the watershed as well.
Though these are the first NetTech devices to be utilized in the Maryland Eastern Shore region, neighboring communities outside of Salisbury, including Talbot County and the City of Easton, have recently installed several NetTech units as well.
It is of the utmost importance to keep trash and debris out of our nation’s waterways, keeping our water as clean as possible for current and future generations, and Oldcastle Stormwater is helping city and county agencies accomplish this task, one step at a time.

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