The Town of Jerusalem, New York, is a picturesque settlement blessed with year-round recreational activities, award-winning wineries, a portfolio of properties listed on the National Register of Historic Places and desirable real estate on the shores of the glacier-formed Keuka Lake.
Beneath the surface, however, the turn of the millennia found failing septic systems were threatening the region’s scenic landscape. The Keuka Watershed Improvement Cooperative (KWIC) verified that deteriorating septic systems mixed randomly with a few primitive holding tanks were compromising the lake’s water quality.
The town had required homes to be scrutinized every five years. If an existing septic system flunked inspection, corrections were required which often included the installation of a new tank and drain field at a cost of $20,000 to $30,000 per residence. In many instances there was not enough room to put in an up-to-date replacement.
A PRIME LOCATION
One of the primary reasons why lakefront homes are sought after in Jerusalem is the pristine shoreline held dear by 4500 residents and thousands of visitors. However, eutrophication generated by septic seepage and other sources of nutrient loading frequently lead to poor water quality resulting in blooms of aquatic vegetation, algae and a potential change in the ecological balance of aquatic habitat.
The town recognized a solution was needed but its particular situation presented some challenging site conditions.
The Y-shaped Keuka Lake is one of the eleven Finger Lakes, so called because of their north-south axis in the west-central region of upstate New York. Its 11,730-acre surface area stretches about 20 miles (32 kilometers) long but from east to west it spans a narrow half-mile to two miles wide. Most of Jerusalem’s waterways flow into the lake where Keuka College and Keuka Lake State Park also reside.
Hundreds of vacation homes (seasonal occupancy is only approximately 20-percent full-time residents) are located very close to the lake, often on small building lots with very little room for septic leach fields. A high water table and ineffective subsurface drainage means the drain fields have poor percolation to begin with, so decline is rapid and inevitable.
The region’s geography is gashed by several gullies and deep ravines that run down to Keuka Lake; valleys and rolling hills used primarily as farm land; and, steep slopes on the waterfront.
It was precisely the natural beauty and rocky terrain the region prizes that would make it laborious, environmentally disruptive and almost certainly cost-prohibitive to excavate for conventional gravity sewering.
BUILDING A PLAN
Gravity sewer systems are the original central sewers with origins in the Roman aqueducts and are almost as old as the biblical city of Jerusalem itself. The bulky systems might require rock blasting and digging trenches 20 to 30 feet (6.1 to 9.1 meters) deep to install large mains and lift stations.
When planning began in late 1999, the town calculated the probable construction cost for a conventional-type system was six million dollars, almost 50-percent more than a $3.2 million low-pressure sewer system (LPS) also being considered. A decade later, a top-level summary of project costs calculated a final tab of $4,080,000 including administrative ($190,000), technical services ($600,000), construction ($2,920,000) and contingency ($370,000).
Community leaders in Jerusalem were aware of several successful regional and local LPS installations. The project team, consisting of representatives from the Town of Jerusalem; Clough, Harbour & Associates LLP (CHA); Siewert Equipment Company; and Environment One Corporation, investigated these projects and learned from them.
Over a period of several years the project team researched the type of sewer system that would best serve residents. Because of topographical constraints, the Town determined that the most economically and environmentally favorable solution was to construct a low-pressure sewer system.
LOW-PRESSURE SEWER SYSTEMS
LPS technology is a simple, effective and inexpensive solution which has been effectively used for more than forty-five years to collect and convey wastewater. The technology was initially adopted in the United States and Scandinavia and is increasingly utilized throughout the developed world. Published case studies of well implemented and smoothly operating systems are widely available.
Low-pressure sewer systems begin at a grinder pump station installed at each residence, which accepts wastewater, grinds its contents into fine slurry and transports it through small-diameter, 2- to 4-inch (51 to 102 millimeters) PVC pipes buried just beneath the frost line to roadside force mains or treatment facility.
The proposed LPS for the Town of Jerusalem eliminated the need for 12 lift stations with a total cost savings of $900,000. Nor did it require a rock excavation outlay pegged at $775,000.
Unlike conventional gravity central sewers, which use up to 24-inch (610 millimeter) pipe and require deep excavation, an LPS system is not destructive to the landscape’s natural or built features and requires less maintenance.
THE ROLE OF GRINDER PUMPS
The grinder pump manufactured by E/One is a self-contained unit barely bigger than a washing machine with a one horsepower motor, controls and level-sensing built into a single unit. It is activated automatically and runs for very short periods. Electrical consumption of the grinder pump is low—a household that uses 250 gallons (946 liters) of water per day should consume less than 10 kilowatt-hours per month to run the pump.
E/One has assembled more than 500,000 grinder pumps at its Niskayuna, New York, headquarters. Its pumps comprise the largest installed base of pressure sewers in the world and E/One alone provides LPS service to more than one million people worldwide.
The town chose E/One because it has a proven record of successful installations around lakes with conditions similar to the Town of Jerusalem’s proposed project. Other E/One waterfront LPS jobs include Martha’s Vineyard, Baja California (Mexico), Hawaii, and many lakefront communities around the United States.
A CLOSER LOOK AT BLUFF POINT
In order for the town’s LPS to maximize its impact, planners chose to site the project at Bluff Point, which gives Keuka its distinct Y shape and is one of the more dramatic lakeside hills in the Finger Lakes. It provides scenic vistas from many of its roadways and cottages along the shore.
Most of the residences are located lakeside on East Bluff Drive and are below the road elevation. The lakeshore elevation of 715 feet (218 meters) is on average 25 feet (7.6 meters) below the centerline of the road. Toward the north end of the district, the road is 50 feet (15.2 meters) or more above the lakeshore elevation. Most residents would be required to have a sewage pump to pump up to a gravity sewer located under the road.
A gravity system to service these far-flung residences distributed on roller coaster elevations was not feasible. With LPS, the wastewater discharged from the grinder pumps can be propelled uphill from the homes, through diverse ground challenges and even around contours. It is effective for distances at more than a mile from force mains or water treatment facility.
E/One, the town determined, was the only manufacturer offering a proven semi-positive displacement type grinder pump able to perform under higher head conditions present in this project.
Unlike centrifugal pumps, the E/One grinder pump produces a nearly constant discharge rate over a wide range of head conditions, including negative head.
The project plan plotted a 5.5-mile (8.9 kilometers) long LPS that discharged into a manhole and flowed to an existing treatment facility in the neighboring Village of Penn Yan. An agreement was reached between the two municipalities that the Town of Jerusalem would pay Penn Yan based on the anticipated flows the new LPS system would be discharging into the treatment plant.
The town decided it would own and operate the new system. The homeowner’s only responsibility would be to provide electrical power (estimated at $24 annually) to operate the grinder pumps. The Town utilized blanket property easements so it possessed the flexibility to locate the grinder pump stations wherever necessary on the small rocky building plots.
As with thousands of other installations, E/One’s grinder pumps were set in the footprint of the property’s septic tank or just adjacent to it making the installations far less environmentally disruptive to private landscapes.
The equipment included the following:
- 29,000 LF of force main pipe
- 30,000 LF of pressurized lateral pipe
- 265 E/One Series 2000 grinder pump stations and alarm panels
- 265 check valves and curb (shut off) valves
- 25 concrete vaults for flushing connections and air relief valves
- 25 flushing connections
- 5 air release valve stations
- 1 bioxide feed odor control system
Because of the seasonal occupancy of most town residents, three informational community meetings were held on Memorial Day, the Fourth of July and Labor Day of 2000. A referendum regarding the project was voted on during a meeting held on Memorial Day of 2001. The referendum passed by a three-to-one margin.
A LOOK AHEAD
A decade after the installation was complete, the Town of Jerusalem and E/One decided to revisit the project. Parts Two and Three of this article provide a ten-year (2003-2013) review of Operation and Maintenance (O&M) data and a hydraulic performance analysis comparing expected design flows to quantitatively measured flows for the 265-unit septic tank replacement project. ■
1. Goncz, Daniel J., “Pressure Sewer System Design, Construction and Operation History at Lake Latonka,” Mercer County, Pennsylvania, June 2010.
2. Albro, Henry S., “Ownership of Pressure Sewer Systems,” with key contributions from the towns of Chelmsford and Marion, Massachusetts.
3. EPA – R2-72-091 November 1972, “A Pressure Sewer System Demonstration.”
4. Wastewater Collection System Modeling & Design, First Edition, Haestad, Walski, Barnard, Harold, Merritt, Walker & Whitman, 2004.
5. Water Environment Federation (WEF) “Alternative Sewer Systems,” Second Edition, Manual of Practice FD-12, 2008.
6. Submersible Sewage Pumping Systems (SWPA) Handbook, Fourth Edition, SWPA 2012.
About the Author
Wayne Ackart, P.E. is town engineer for the Town of Jerusalem. Clark A. Henry is director of engineering at Environment One. He can be reached at . Michael Crowley is LPS system designer at Environment One. For more information on Environment One Corporation’s full line of grinder pumps and LPS solutions, visit www.eone.com or call 518.346.6161.
MODERN PUMPING TODAY, September 2014
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