REPLACING A SANITARY LIFT STATION IN PARKLANDS: AN EXERCISE IN COOPERATION
Abstract:In the 1960s, a sanitary lift station for the developing Northeast Quadrant of the City of Solon, Ohio (City) was constructed at the natural low point: a valley in a park. The park, now called South Chagrin Reservation, is part of the Cleveland Metroparks (Metroparks) system. In 2003, the City recognized that the lift station was approaching the end of its useful life and decided to replace the station before a catastrophic event occurred that could damage the sensitive environment around the lift station and interrupt service to the 950 tributary households. The City and the Metroparks cooperated throughout the design and construction of the new lift station to address technical constraints, physical limitations, environmental concerns and differing priorities.
The lift station is located in a small valley, adjacent to an unnamed stream that is a natural brook trout stream. During an I/I Study conducted by the City's consultant, Metcalf & Eddy (M&E), the lift station was identified as a hydraulic bottleneck. Additionally, during some large rain events, evidence showed that the wet well would become pressurized and sewage would seep out through the wet well cover and overflow to the adjacent stream. A draw down test was performed on the lift station by the City. Each pump was designed for 800 gpm at 70-ft TDH. Separately, the pumps were operating at 372 gpm and 566 gpm. Both pumps together produced 913 gpm. Rather that rehabilitating the station, the City undertook to replace the lift station because of the age of the facility and a number of on-going O&M problems in addition to the pump performance.
The fact that the lift station was located on a very small site, had to stay in operation during the construction of a new facility and was located on park lands made the design of the new station challenging. While neither the City nor the Metroparks liked the location of the lift station, both realized that the terrain and the configuration of the influent sewers did not make relocating the station a practical option. The City, the Metroparks and M&E worked together through the design of the new lift station to site the facility and route the force main in ways that were adequate for the technical requirements of the facility and minimized impact on the environment. This was challenging as the priorities of the City and the Metroparks often differed.
The consensus was to relocate the lift station approximately 100-ft behind the current location on a new site to be provide by the park. This allowed the current lift station to remain in service during construction, which was a requirement since it is the only means of service to approximately 950 households. The force main route was negotiated in the field to minimize impact on high quality trees, including a grove of beech trees, and to provide an access corridor for use by the City for future maintenance or repair needs. The force main was to be installed using horizontal directional drilling (HDD) of high-density polyethylene (HDPE) pipe. For the City, the pipe offered flexibility with few joints. For the Metroparks, this allowed the pipe to be installed under trees below the root mass which has less impact than open cutting.
During construction, the City, the Metroparks, M&E, together with the contractor, Kenmore Construction, continued to work together to construct the facilities while the park was open to the public. The Metroparks allowed the Contractor to use administrative and maintenance areas for trailers, parking and lay down areas. The City, M&E and the Contractor maintained communication with the park manager to coordinate activities that impacted the bridle and all-purpose trails or main roadway. The amount of effort spent coordinating priorities and goals during design and continuing that effort through communication during construction resulted in the construction of a new facility that will serve the public while protecting the environment for decades to come.
The high level of communication established early in the project design phase and maintained through construction was a financial investment for the City, due to the number of meetings, phone calls, etc. The approach had several benefits including establishing realistic expectations and an understanding of the priorities that shaped the positions of the various stakeholders. The approach did not eliminate conflicts of opinion between the various parties but did work effectively to find ways to move the project forward.
Document Type: Research Article
Publication date: January 1, 2007
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