Sea Girt Pump Station Mobile Enclosure
Improving the Environmental infrastructure of a Small Coastal Community
Sea Girt Avenue Pump Station Reconstruction
In 1972 the federal Government passed the Federal Water Pollution Control Amendments; commonly known as the Clean Water Act. The CWA regulates the discharge of sanitary sewerage into rivers, lakes and the ocean. The bill was in response to the pollution and health risks associated with the discharge of sewage into bodies of water. The Clean Water Act affected many coastal communities who owned and operated sewage treatment facilities along the Jersey shore. Several of these communities joined together to meet the newly initiated standards and created the South Monmouth Regional Sewerage Authority (SMRSA) in 1970. The SMRSA franchise area includes eight municipalities: the Boroughs of Belmar, Brielle, Lake Como, Manasquan, Sea Girt, Spring Lake, Spring Lake Heights, and the Township of Wall. SMRSA owns, operates and maintains eleven sewage pump stations and a sewage treatment plant. Ten of the pump stations pump into a common force main (trunk sewer) for conveyance to the treatment plant. The individual municipalities are responsible for their own collection systems and conveyance to the Authority’s sewage pump stations. The majority of the Authority’s sewage pump stations were constructed and placed into operation in the 1970’s.
Up until the 1970’s, the Borough of Sea Girt owned and operated a sewage treatment plant on Sea Girt Avenue, which was constructed in the early 1900’s. With the creation of SMRSA, the sewage treatment plant was converted into a sewage pumping station by “sectioning off’ a portion of the existing below grade settling tank. Aside from regular maintenance to the station, no major rehabilitative or reconstructive work had been performed and the station had reached the end of its useful life due to age, the inability to obtain spare parts, and the deterioration of the above grade structure.
The location of the pump station is in close proximity to the beach and the Atlantic Ocean which poses a constant threat of storm surges and damaging winds. The Sea Girt Avenue Pump Station, as well as other pump stations operated by the Authority, has been flooded and/or damaged in the past by coastal storms. This potential for flooding was a key factor that had to be taken into consideration for the design of the pump station reconstruction.
In 2006, the South Monmouth Regional Authority authorized Consulting Engineer, Michael J. McClelland, P.E. of CME Associates to investigate, evaluate alternatives and conceptualize a project to reconstruct the pump station with the provision that said station in so far as was possible, be “hurricane proof.”
The investigation and evaluation began with the existing above grade masonry and timber structure. The structure had become deteriorated over the years due to its exposure and method of construction. There was also a concern that a storm surge or heavy winds from an ocean storm could catastrophically damage the structure. Therefore, replacement of the structure was determined to be required.
The relocation of the station was also investigated, but due to costs and land and site restrictions, it was determined not to be feasible. The original treatment plant was constructed within the right of way of Sea Girt Avenue. When the pump station was constructed within the footprint of the treatment plant, it remained within and to one side of Sea Girt Avenue. Site constraints included: beach dunes and the Atlantic Ocean to the east; residential housing to the north; Sea Girt Avenue to the west; and the New Jersey National Guard camp to the south. The area of the camp adjacent to the pump station is undeveloped, consisting of dunes and natural, native vegetation. Access to the area near the beach was restricted to minimize damage the vegetation and animals. The possibility of obtaining the NJDEP Land Use Permits required to relocate the station to this site was determined to be unlikely and it was removed from consideration. Additional considerations include the high costs of excavation, dewatering and concrete work that would be required in an area of sandy subsurface materials and high-ground water due to proximity to the ocean. Accordingly, it was decided that the existing below grade wetwell and drywell would be improved and reused as part of the rehabilitated station.
The high probability of storm flooding and damage, which could have resulted in the loss of sanitary sewer service for an extended period of time, led the project team, consisting of the Authority and CME Associates, to arrive at a unique design concept -housing the primary electrical equipment and controls in a mobile enclosure adjacent to the wetwell and drywell. The enclosure would elevate the equipment that cannot be made emersible above the level of flood damage. It also provides the Authority with the ability to remove the enclosure from the site to a safe inland location should a severe storm or hurricane with damaging winds or storm surge occur. After the storm event passes, the enclosure can be returned to the site, thus resulting in minimal disruption of sewer service. The enclosure consists of two rooms, one sound attenuated room for the emergency generator and another climate controlled room for the electrical equipment, including: controls, alarm systems, variable speed drives and various other components. Electrical and control connections between the enclosure and the pump station and its equipment are made with cables and plugs that can be opened to permit removal of the enclosure.
In the event of an imminent coastal storm with the potential to cause damage to the pump station, the enclosure will be moved from the site to a safe inland location. An expendable portable generator and transfer switch will be transported to the site to operate the station if utility power is lost. A secondary, sacrificial electrical and control system, permanently mounted at the site, will operate the comminutors and pumps on utility or generator power. Once the storm subsides, the enclosure can be moved back to the station and all electrical equipment put back.online. This capability will minimize any damage to the station’s electrical equipment and significantly reduce any downtime of the station. The effect will be to return the station to normal operation within hours of the passing of the storm whereas, with a conventional station, if the electrical and control equipment were to be damaged, the station could conceivably be out of service for weeks until the
equipment was replaced, thus resulting in significant environmental damage.
The construction included a new concrete slab at grade. The top of slab is at least 8 inches above the surrounding grade to keep stormwater out and to prevent vehicles from driving onto the top of the slab. The operating slab has hatches to allow access into the wet and dry wells and for removal of equipment. The existing wet well intermediate level was demolished to provide better access for maintenance and cleaning. New concrete influent channels with a primary and back-up comminutor were installed. All equipment installed in the wetwell or drywell are suitable for immersion or considered sacrificial (not essential to the operation of the pump station and easily replaced). Thus, if the station is flooded, all of the essential equipment (pumps and comminutors) located below grade will be able to continue to run without damage.
The existing pumps, piping, and valves were removed and new dry pit submersible pumps, valves, piping and a flow meter were installed in the dry well. An aluminum staircase was constructed for access from the surface slab down to the dry well. The pumps, comminutors and their motors were rated for immersion duty should the wetwell or drywell flood.
The project was constructed over the winter such that there would be no adverse impacts to the residents during the summer season.
The completion of the project has resulted in a new station that: fully complies with all of today’s stringent regulatory codes; utilizes modern equipment selected for longevity and minimal maintenance requirements; and provides the highest degree of reliability with the least adverse environmental impacts under storm events.
Mr. McClelland’s design has enabled the Authority to achieve its objectives by replacing antiquated equipment at a dilapidated facility. The Borough of Sea Girt and its residents have also benefited by the removal of an antiquated and unappealing structure and now have a new, hurricane proof pump station that will provide years of reliable service.