FORMER TOP FEDERAL EPA EXPERT SAYS ALTERNATIVE (LOW COST) SEWERS CAN SAVE CHATHAM TAXPAYERS AS MUCH AS $100 MILLION
CONVENTIONAL SEWERS VS. ALTERNATIVE (LOW COST) SEWERS
Jim Kreissl is the Environmental Protection Agency’s former principal technical expert for small community wastewater collection, treatment and reuse systems and onsite wastewater systems.
1. The cost of the recommended conventional gravity sewer for Chatham is about $200/ linear foot. This is about twice that expected in the US. It represents 83% of the total cost of the project or $240,000,000. In contrast, the more than 1,000 alternative collection systems (e.g., effluent sewers, grinder-pump pressure sewers, and vacuum sewers) installed in the country have averaged around $10,000 per house served. When compared to conventional sewering, these systems have generally saved from 25% to 50% of the capital cost. The inclusion of 80 lift stations in the Chatham planned conventional centralized sewer will drive up the cost of operation and maintenance significantly by at least $250,000/year and require hiring several additional employees by the town.
2. Alternative sewers consist of small-diameter plastic pipes that are buried below the frost line (usually about 30 in.), while conventional sewers are usually buried from 8 to 20 feet below the ground. The alternative or “low-cost” sewers can be laid by smaller equipment that is not limited to roadways. They also employ longer, lighter-weight pipe lengths and quickly-fitted elastomeric pipe joints. Thus, because much greater lengths of pipe can be laid per day, the community disruption is significantly less and shorter in duration.
3. These low-cost systems, with fewer and more water-tight joints, reduce the potential for infiltration and inflow (I/I). Coupled with their location, generally above the water table in Chatham, while conventional sewers lie below it, the potential for infiltration and inflow is greatly reduced. This means that only wastewater is to be treated at the treatment facility, not a mixture of wastewater and I/I fresh water that is the case with the conventional system. This saves the cost of unwanted additional treatment and dispersal capacity at the facility.
4. Alternative sewers do not need manholes, a feature required in conventional sewers every 250 or so feet (depending on the rules). These features cost about $2,000 each and offer opportunities for additional I/I to reach the sewer. By their nature, alternative systems also minimize the need for lift stations that are also expensive to construct and to maintain (there are 80 of these in the Chatham recommended plan).
5. One of these alternative sewers could be substituted for the proposed conventional sewer in Chatham and could easily save close to $100,000,000.
6. The potential impacts of the conventional sewer on Chatham are the growth-inducement that invariably follows its installation in order to reduce the cost per user, the potential drainage of the valuable fresh water lens that exists under the town, and the lengthy and severe community disruption during the next 30 years of proposed construction. If growth is what the citizens of the town want, they will surely get in spades after the sewer is built. If several neighboring communities also opt for the conventional sewer, the freshwater lens along the south coast of the Cape will be severely reduced, promoting saltwater intrusion under the land area and potential reduction of fresh drinking water along the Cape. Finally, the disruption that the town’s permanent population will endure over the next few decades will be severe, with a lack of alternative routes to take while main streets are blocked and businesses are jeopardized for lack of access to patrons. Even with seasonally limited construction, these problems will also likely impact seasonal residents.
7. The best way to maximize the potential value of alternative sewers is to consider using a decentralized approach. For example, if naturally draining, nitrogen elimination areas (target areas or hot spots) are identified, alternative sewers could deliver the wastewater from the sources (homes and businesses) to a cluster or neighborhood facility for treatment by passive means and infiltration or reuse. This will assure that the freshwater aquifer will remain intact and that the energy and facilities to remove it to another watershed will not be required. This approach reduces the amount of pipeline length required for collection and can be used to retain community character by not inducing unwanted growth in that area. New development will be required to manage whatever wastewater it will generate in its development plans and will be subject to the management of the sewer management authority.
8. In outlying areas that are difficult for even low-cost sewers to reach, onsite nitrogen removal systems can be required subject to the oversight of the sewer management authority. That authority may choose to operate and maintain these systems with internal staff or hire contractors to do so. The management task is far less than that required for the proposed Chatham conventional sewer system with its 80 lift stations, many, many miles more of deeply laid piping subject to enormous infiltration and inflow, several hundred manholes and required main flushing.
9. The technologies are available for alternative sewer systems to remove nitrogen at whatever the treatment level is –central, cluster or individual onsite locations. These low cost systems can be equipped to handle phosphorous (for fresh water ponds) and contaminants of emerging concern such as pharmaceutical residues and other chemicals. Alternative systems also typically provide UV disinfectant, which the proposed Stearns & Wheler plan seems to omit.
10. These systems are very reasonably priced, particularly in light of the recommended Chatham solution. Any state limitations or restrictions about their use should be evaluated and promptly modified in light of the huge economic overall Cape Cod needs. They are in widespread use throughout the United States and in Canada. Without question, these alternative systems provide the most cost effective solution for taxpayers. They are also environmentally superior.
11. The use of the Nitrex porous reactive barrier (PRB) technology utilizing the patents of the University of Waterloo in Ontario is particularly intriguing owing to its ability to provide an immediate reduction of the thousands of pounds of nitrogen that already exist in the ground water around the Cape that is moving towards the coastal waters. All other technologies will not have any impact for several years owing to the time it will take to flush the aquifer of those existing contaminants.
Additional information about Jim Kreissl
Jim Kreissl, Environmental Consultant, formerly of the U.S. Environmental Protection Agency, Small community wastewater systems
Until his retirement, Jim Kreissl was the Environmental Protection Agency’s principal technical expert for small community wastewater collection, treatment and reuse systems and onsite wastewater systems. He now serves on the Water Environmental Research Foundation’s Decentralized Research Advisory Council, is an affiliate of the National Environmental Services Center and, until recently Chairman of the Water Environment Federation’s Small Communities Committee. Now as a consultant at Tetra Tech, he has authored several EPA reports designed to promote effective management of decentralized/distributed systems and has made many presentations at conferences and workshops on these topics. Mr. Kreissl holds degrees in civil engineering and sanitary engineering from Marquette and the University of Wisconsin. He makes his home in Kentucky.