Combined Sewer Overflows (CSO's)
What are Combined Sewers?
To better understand Combined Sewers we also need to know what other types of sewers we have in Cumberland. Besides Combined Sewers we also have Sanitary Sewers and Storm Sewers.
Sanitary Sewers carry untreated human waste and wastewater from homes and business to the Wastewater Treatment Plant.
Storm Sewers carry storm water (rain, melted snow, etc.) run-off from building roofs, streets, and parking lots to nearby streams, creeks, and rivers.
Combined Sewers which normally function the same as Sanitary Sewers, also receive the storm water run-off. Since they function like both the Sanitary Sewers and the Strom Sewers, they have been named Combined Sewers (sometimes called Combination Sewers).
What are Combined Sewer Overflows (CSO’s)?
Combined Sewer Overflows (CSO's) are the discharge of untreated wastewater from Combined Sewers directly into a waterway. They usually occur as a result of heavy rain that causes the capacity of the sewer to be exceeded, and are discharged by a control structure such as a Diversion Manhole or a Regulating Chamber.
Why do we have Combined Sewer Overflow’s (CSO’s)?
Like many Cities established in the 1800's, the first sewers developed in Cumberland were combined sewers. All wastewater and surface runoff went directly to the rivers and streams through these collector sewers. Some of the streams such as Dry Run, Sulphur Hollow Run, Mill Race, and others where later encased by conduits or lined with sewer pipes before being covered. As our city grew, it become clear that there wasn't enough water in the streams to assimilate our wastewater.
In the early 1900's the City began studies of its existing sewer and water systems in an effort to plan the utilities for it's continual expansion. During 1934 and 1935 an Interceptor Sewer System was constructed to collect the flow from sewers in North Cumberland, Downtown, West Side, and parts of South Cumberland. In 1936 and 1937 an "Outfall" or Interceptor Sewer was constructed from the Lindnerville area (Baltimore Ave., Willowbrook Road, and Pine Ave. area) of Cumberland along Willow Brook Road and Evitts Creek to the mouth of Evitts Creek. Then in 1957 the "Primary" Cumberland Wastewater Treatment Plant was constructed along with the Evitts Creek Pumping Station and several other interceptor sewers. The plant discharged the treated effluent to the Potomac River. In 1976, the City of Cumberland upgraded its "Primary" treatment plant to a "Secondary" Wastewater Treatment Plant utilizing the conventional activated sludge process. The City of Cumberland has continued to upgrade the Wastewater Treatment Plant and City forces are constantly engaged in preventive maintenance and improvements.
The City of Cumberland's existing sewer system includes a network of collector and interceptor sewers, over 105 miles in length and ranging in size from 4" to 60". The collector sewers are usually combined (carrying both storm and sanitary), although some areas of Cumberland do have separate storm and sanitary systems. It is generally at the point where the combined systems enter the interceptor sewers that diversion manholes and regulating chambers are located. These points are the source of Cumberland's Combined Sewer Overflows and were designed to relieve the high flow, which occurs during heavy precipitation.
Where do these overflows occur?
The City of Cumberland's existing sewer system includes a network of collector and interceptor sewers, over 98 miles in length and ranging in size from 8" to 60". The collector sewers are usually combined (carrying both storm and sanitary), although some areas of Cumberland do have separate storm and sanitary systems. It is generally at the point where the Combined Sewers enter the Interceptor Sewers that diversion manholes and regulating chambers are located. These points are the source of the City's Combined Sewer Overflows and were designed to relieve the high flow that occurs during heavy precipitation.
How expensive is it to prevent CSO’s
It is very expensive to prevent CSO's.
In coordination with the National Park Service's (NPS) Canal Rewatering Project, the City of Cumberland has focused it's attention on the problems with it's Combined Sewer System (CSS) within the same area as the NPS Canal Rewatering Project. The City hired Whitman, Requardt, and Associates (WR&A) to do preliminary design for the Combined Sewer Overflow (CSO) project. Phase I-A of the project complete, and the approximate cost of the project was almost $12,000,000. Funding included an EPA Grant in the amount $5,000,000 and several grants from the Maryland Department of Environment (MDE).
The estimated cost of the entire project in the area of the NPS Canal Rewatering Project is over $30,000,000. And while this should prevent the CSO's problems that have occurred in this area, it may not totally eliminate them and will not solve the problem in other areas of the City of Cumberland.
So as you can see, it is very expensive to prevent CSO's. And CSO's cannot be eliminated without the assistance of Federal, State, and Regional agencies. However, the City of Cumberland is taking steps to reduce the number of CSO occurrences, and you can help too. Please read the following sections for more information.
What is the City of Cumberland doing about CSO’s?
In March of 1994 the City of Cumberland prepared a CSO PLAN OF ACTION for submittal to the Maryland Department of Environment. While assembling the CSO PLAN OF ACTION it became clear that many of the Operational and Maintenance related items outlined in the plan were already being performed by City forces. The plan was put into effect immediately. In June of 1997 the CSO PLAN OF ACTION was revised and submitted to the Maryland Department of Environment.
Operations and Maintenance work performed in accordance with the CSO PLAN OF ACTION includes: Inspection of the Overflows, Maintenance & Inspection of the Regulating Devices, Catch Basin Cleaning, Maximize treatment at the Wastewater Treatment Plant, Street Sweeping, Reduce use of Gravel or Sand in Snow Removal, Enforcement of Industrial Pretreatment Program, & TV Inspection and Power Cleaning of Sewer Lines.
Capital Improvements performed in accordance with the CSO PLAN OF ACTION includes: Modifications to Existing Regulating Devices, Improved Mapping of the City's Sewer System, and Expansion of Existing Storm Sewer System.
In October of 1998 as a part of the City of Cumberland's continued CSO reduction effort a LONG-TERM CONTROL PLAN FOR COMBINED SEWER OVERFLOWS was prepared by Whitman, Requardt and Associates, LLP of Baltimore, Maryland. This plan was submitted to the Maryland Department of the Environment as required by the Schedule of Interim Deliverables in NPDES Permit No. 96-DP-0567.
The main focus of the LONG-TERM CONTROL PLAN was CSO activities related to the National Park Services' C&O Canal Rewatering Project. The plan also outlined the Inventory of Overflow Locations, the start of a CAD-based map of the sewer system, the system monitoring, and system modeling.
Prior to the development of the CSO plans the City of Cumberland had previously eliminated several CSO's. One overflow and discharge point was eliminated with the improvements to the Wastewater Treatment Plant in the late 1975, and another was eliminated with the construction of the Candoc Lane Storm Sewer in 1977. Also the weir height was raised in several diversion manholes to reduce the number of CSO occurrences.
Another effort by the City which helps to reduce or eliminate CSO's includes the installation of storm sewers, where possible, during the reconstruction of City streets. The installation of the storm sewers not only helps with the CSO problem, but extends the life of the roadway.
What can the public do about CSO’s?
Do not dump into catch basins and curb inlets.
A large portion of the curb inlets in Cumberland have previously been painted with the signs "Chesapeake Bay Drainage Area" and "Do Not Dump". This was accomplished by many volunteers. By not dumping items into the basins and inlets, it should reduce the amount of debris and floatables that sometimes get flushed through the system during a rain. This along with the City's efforts of Catch Basin Cleaning, Street Sweeping, and Reduced use of Gravel or Sand in Snow Removal; will prevent debris from getting into the sewer system and can reduce the frequency for the need of power cleaning of the sewers, and maintenance problems (associated with grit and debris) at the overflows, pumping stations, and Wastewater Treatment Plant.
This joint effort between the City and the public will minimize the amount of floatable materials and sedimentary problems in the adjoining streams. It will also ensure that the sewers can carry the maximum amount of flow without overflowing.
Report Overflows as soon as they occur.
The City has placed the following signs at all the outlet points:
HELP YOUR CITY
IF YOU SEE FLOW FROM
THIS PIPE IN DRY WEATHER,
PLEASE CALL 759-6600
If you see an overflow and report it immediately, it will make the City aware of any overflows that occur between inspections. If the overflow occurs due to a blockage in the sewer, it will allow the City to quickly repair the problem and thus reduce the overflow to a minimum; and if it occurs due to wet weather, it will help the City estimate the duration of the wet weather overflow and thereby improve the accuracy of the quantity estimates of the overflow. |
