Experts Address Sewage Leaks At Intersection of Washington and Colonial Ave
Project Manager, Heather Campbell and Richard Kincheloe (Subject Matter Expert when it comes to hydrophilic modeling according to Heather) were on hand at the July Colonial Beach Town Council Work Session to give an update on the I and I problems facing the town and to shed light on some disturbing sewage leaks that occurred during recent heavy rain events.
Dewberry (formerly Dewberry and Davis) has been working with Colonial Beach on I and I problems for over 20 years. Recently the town discovered that during heavy rain events the manhole cover at the intersection of Colonial and Washington Ave. was overflowing and seeping sewage.
Heather Campbell explained that this area is identified as one of 4 central drainage locations in Colonial Beach.
I and I stands for Inflow and Infiltration.
Inflow refers to direct rainwater flowing into the towns sanitary system. This usually comes from rainwater drainage systems being directed into the sewer system pipes which, in the Town of Colonial Beach, is illegal and carries a fine.
In older houses especially it was a practice to direct storm water drains around the house to drain into the public wastewater pipes. This has long been recognized as a drain on the sewage treatment plants and interferes with proper sanitation of sewage. It is illegal to direct any rain catching vessels into the town sewer system. It is also illegal to drain a swimming pool or other non-sewage into your homes clean out valve. This violation carries a fine.
Infiltration is a slower process of rainwater seeping into sewer pipes through cracks or openings in the system.
Richard said that Colonial Beach was able to provide much more detailed information, than most small towns, on the waste water operations. They credited this information to the recent water meter upgrade.
Colonial Beach is very level so the piping and collection systems carrying waste to the treatment plant consists of several pumping stations. Richard reminded the council that wastewater pipes are always subject to wear and tear so they are constantly in need of repairs. Growing populations and new construction continues to put more demand on the system requiring continuous upgrades as well.
However one big cause for concern has been a manhole located at the intersection of Colonial and Washington Ave, which during heavy rain events has been observed to be leaking sewage. The cause is a very old drainage system according to Dewberry.
The team at Dewberry has conducted an extensive study of the problem and have concluded that the main cause for the malfunction stems from the fact that the pipe size carrying water away from this area is inadequate.
Richard Kincheloe said that the pump station is able to keep up with the flow during the rain event so that indicates that the pump station isn’t the problem, however the pipe that carries water away from this area is not large enough to carry the excess flow during high rain events, thereby causing a back up.
The solution to the problems is to replace the existing 8 to 10 inch pipe with a larger 12 inch pipe. Up-sizing by one size may not seem like much but it will significantly change the amount of water that can be handled.
There will need to be some survey and design work to give a more exact price but they estimate a ballpark cost for replacement at around $870,000.00 for the one solution of changing the pipe. This takes into account traffic control, pavement replacement as well as line replacement.
Enlarging the lines are a quick fix according to Richard, but he suggests a more permanent solution involves also addressing the I and I problems. By eliminating unwanted rain water from entering the system using meter data from customer water usage, public works can stay on top of the needs for future demand on the sewer system.
In other words knowing exactly how much water is flowing in can allow staff to better estimate what will flow back out.
Richard Kincheloe recommends collecting more date by stationing a man stationed at each affected manhole and one at the corresponding pump station to observe what happens in a heavy rain event. Although the town doesn’t want to see flash flooding for the residents sake Mayor Robin Schick hoped that the remnants of Tropical Storm Ida could provide the town the opportunity to conduct these tests.
Mayor Robin Schick gave us an update on the progress of the I and I work. When asked if any work had been done since they Dewberry representatives, Heather Campbell and Richard Kincheloe, presented this information Mayor Robin Schick said, “Since their presentation we have moved forward with the I&I data collection they requested, IDA and other rain events are going to help us get the data they need to then set in motion which areas will be targeting for inflow problems and smoke tested.”
“The pipe sizing engineering is part of this next step as well.” Schick added that she is hoping to be under construction early in the new year.
Schick said she believes storm water impact fees will eventually have to be discussed, they have been implemented across the state already.
But Schick also said, “It’s a fee that can be discounted if you mitigate to be responsible with your homes storm water.” but she added the warning that if you’re putting storm water into the sewer system you can be fined.
If the town does begin talks concerning storm water impact fees Schick said the town would research how other localities set, implement and enforce the fees as well as look into mitigation strategies homeowners can use to get a reduction on those fees.
One great way to not only help your properties drainage but also mitigate any possible fees in the future is to install a rain garden. You can read all about rain gardens here. Rain Gardens Can Help Mitigate Standing Storm Water
* Dewberry is a nationwide firm of planning, design, and construction professionals.
More reading on the subject: Town Talks on Storm Water Drainage
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