Bond Brook CSO3 Project

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The District is working on its third phase of what is expected to be four phase effort to address combined sewer overflows (CSO).  This is a $17M project that will reduce the frequency of sewer overflows into the Kennebec River.  This project is required for compliance with the Clean Water Act as administered by the Maine Department of Environmental Protection.

In Maine, the Department of Environmental Protection enforces the CSO rules for EPA under Chapter 570, "Combined Sewer Overflow Abatement".

In Augusta, the Greater Augusta Utility District has been actively managing CSOs for over a decade.  The CSO3 project represents the third phase of CSO compliance.  This round of work centers on the area near Bond Brook.  This will eliminate 4 CSOs that currently dump into Bond Brook.  It will also improve an out of date sewer system, replace two old pump stations with one new one, improve flow into the wastewater plant and comply with upgraded river quality standards to reduce the amount of e. Coli that enters the Kennebec River by rebuilding the plant's effluent disinfection system.

Why do we have "combined" sewer and stormwater systems?  When Augusta was young, there were different problems to solve and this led to different solutions.  Before people really understood the impacts of dumping sewage into waterways, it was convenient to dump it into local streams and rivers.  Because pipes were expensive to install and had to be dug by hand one pipe was typically used to carry both stormwater (rain) and sewage (toilet waste).  Eventually people noticed that the streams and rivers were in poor condition and scientists determined that something else should be done with wastewater.

How do combined sewers work today?  Modern combined systems collect the vast majority of the sewer and stormwater.  This water is pumped to the wastewater treatment plant.  However some storms are too big to be contained in these systems and some overflows are necessary for cost considerations. 

What is a CSO?  CSO stands for Combined Sewer Overflow.  Some older sewer systems also act as drainage systems for streets and buildings.  Under certain rainfall conditions, the amount of sewage and rainwater that enters the pipes is too much for the pipes to carry and they overflow human waste into streets, streams and rivers.  EPA has long recognized the health risks associated with combined sewer overflows and has regulations under the Clean Water Act that ensure that these public health threats are addressed.  Click here to find out more information from the EPA.

How does a CSO "work"?  The graphic below shows how combined sewers work in dry weather and wet weather.  When it's not raining combined sewers push wastewater (mostly sewer water only when it's dry) to the wastewater plant for treatment.

When it rains, so much water can rush into the pipe that the rain water and the sewage flow out into the brook or river.  The remaining water rushes into the wastewater plant and causes the plant to work poorly which can result in failure to meet environmental standards.  By upsizing the combined sewers more water can be treated at the wastewater plant which reduces the amount discharged to streams and helps keep the brooks and rivers clean.  The advantage is that the larger pipes slow the flow to the wastewater plant which helps the plant work better.