Brookland Terrace Civic Club: Updated 13 March - Brookland Terrace Sewer Inspection / Flushing

10.3.20

Updated 13 March - Brookland Terrace Sewer Inspection / Flushing - April 2020

Brookland Terrace Sewer Inspection / Flushing - April 2020

Subject: RE: sewer inspection/flushing

10 March 2020

The Brookland Terrace subdivision received a chemical root control treatment back in early January and we wait a minimum of 3 months before returning to perform cleaning work.

This 3 month time period allows the chemical root treatment to be most effective.

Therefore, we are scheduled to perform the preventative maintenance work for Brookland Terrace in April.

I would also like to share with you that we intend to utilize some of our new technology to minimize the impact of the maintenance on the community.

We plan to first perform acoustical testing on the sewer mains.

This technology uses sounds waves to identify which lines are in need cleaning and which ones are clear.

Our experience with this acoustical testing process is that typically about 70% of the sewer lines in subdivisions do not need to be cleaned with our hydraulic cleaning trucks.

For lines that are identified to be cleaned by the hydraulic cleaning trucks, we plan to use a new type of nozzle that became available to us just in the last few years called a “anti-blowback” nozzle.

The nozzle is engineered to manage and control the airflow in the sewer to help prevent blowbacks into the homes.

Our use of these nozzles has proven they are helpful in communities that are susceptible to blowbacks.

The only drawback it is that it can take more time to clean the mains versus using other nozzles in our inventory, but that is preferred over inconveniencing our customers with a blowback.

Please forward this information on to the community and I will reach back out as we get closer to the work beginning in April.

Regards,

Kevin Penoza P.E.

Acting Operations Services Manager

New Castle County

Department of Public Works

187A Old Churchmans Road

New Castle, DE 19720

Office: 302-395-5723

Kevin.Penoza@NewCastleDE.Gov

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13 March 2020

Our goal with utilizing the acoustical testing and anti-blowback nozzles is to ensure we minimize backing up any basement drains or causing blowbacks from plumbing fixtures. We perform the preventative maintenance on the sewer mains to prevent blockages created by roots, grease, and debris. These blockages will cause more significant basement backups and potentially overflows into the environment.

In regards to the product that we utilize for chemical root control, it was designed not to harm trees and would not be the cause of the tree issues described below. A very small percentage of the tree root system actually lives in the sewer pipe. The root control treatment will only kill the roots inside the pipe and approximately twelve inches outside the pipe. The product is called Razorooter II and we have been utilizing it at the County for over 12 years now with no experience of trees being adversely harmed. The company that provides the service to the County is, Duke’s Root Control, and they have been performing sewer line root control work for thousands municipalities across the United States for almost fifty years. They have treated well over 290,000,000 feet of sewer pipe since being in business. In all of this work, they state that they have never damaged a tree.

The herbicide used by Duke’s, diquat dibromide, is chosen for its efficacy and favorable toxicology profile. Diquat dibromide is commonly used as an aquatic herbicide and is approved by the EPA to treat vegetation in ponds and waterways. It is non-toxic to fish at herbicidal concentrations. Diquat dibromide binds firmly to organics in the soil and becomes inactivated. It therefore does not leach through soil into the groundwater. Any residual material that reaches the wastewater treatment plant is removed by wastewater treatment plant processes. The formulation of diquat dibromide is registered with the US EPA as well as the Delaware Department of Agriculture.

The County first performed chemical root treatment in Brookland Terrace in 2018 and the second treatment just occurred this past January. The next scheduled treatment won’t be for three more years in 2023. Several subdivisions in the County began treatment with this product as far back as 2007 and have received five treatments to date.

Roots in a sewer system usually do correlate with water infiltration as well. Our Department performs evaluations of the life cycle costs of maintaining the pipes and the impact and of the leaking pipes to determine when replacement or rehabilitation is necessary for structural or capacity reasons. In most cases, due to the high costs of rehab and replacement, it is more cost effective to manage the roots through maintenance if the pipe does not have structural problems and the infiltration is not significant enough to cause capacity concerns.

The alternative to using herbicides to control roots in sewers is mechanical root cutting. The drawback to mechanical root cutting is that each time the roots are cut they grow back thicker and fuller. Mechanical root cutting is a much more aggressive cleaning process and will increase the potential for basement backups and blowbacks. It also must be performed more frequently then chemical root control, at least once a year versus every three years for chemical root control. The mechanical root cutting process is hard on the sewer pipe and along with ever returning thicker roots will accelerate the deterioration of the pipe.

Pipe replacement projects also unfortunately usually require removal of some trees due to their close proximity to the sewer mains. Using herbicides to control the roots does not damage the tree, since it kills roots only a few inches outside the pipe. By safely controlling root intrusions, herbicidal root control prevents the tree from becoming nuisance vegetation around our infrastructure. So the herbicidal root control insures the survival of the tree in an suburban environment by lengthening the life of the sewer main.

Please share this information with the community and they are certainly welcome to contact me directly if they have more questions or wish to discuss.

Some additional information on Duke’s Root Control and the product they use is also attached.