Island Beach State Park is one of New Jersey’s last significant remnants of a barrier island ecosystem that once existed along much of the coast and is also one of the few remaining undeveloped barrier beaches on the north Atlantic coast. Over 3,000 acres and 10 miles of coastal dunes remain almost untouched since Henry Hudson first described New Jersey’s coast from the ship, the Half Moon, in 1609.
The New Jersey Department of Environmental Protection (NJDEP), Division of Parks and Forestry (DPF) along with the New Jersey Department of the Treasury, Division of Property Management and Construction (DPMC) issued a Request for Proposal (RFP) seeking the services of an engineering firm/team to provide design and construction related services for a new sanitary sewer collection and conveyance system within Island Beach State Park (IBSP). Currently, IBSP utilizes on-site subsurface sewage disposal systems (i.e., septic systems), pit toilets or composting toilets, depending on the location, intensity of use and available utility resources at each particular location. Through a three-step proposal process (Preliminary Proposal, Technical Proposal and Fee Proposal), the professional design team, consisting of LAN Associates and CP Engineers was selected as the design professionals for the proposed project.
The initial RFP by the DPMC requested the design of a conventional collection/pump station and force main system to replace the existing septic systems for many of the facilities at IBSP. During the Preliminary and Technical Proposal phases of the RFP, it was identified by the project team that due to the unique nature of the IBSP facilities (i.e., exceptionally heavy use during the summer season and minimal use during the off season) and the resulting variation in seasonal sanitary sewage flows, combined with the long force main lengths needed and the significant environmental constraints, the conventional system design may not be the most economical or best option for collection and conveyance for entire IBSP project. Researching potential options, the project team identified vacuum systems as a viable alternative to the traditional force main sanitary sewer system.
Between 1850 and the early 1900 there were several hotels and a tavern on Island Beach. The Interpretive Center (Reed Hotel) was built in 1876. In the early 1930’s The Barnegat Bay and Beach Co. built three homes on the island, the present Governors house on the ocean, the superintendent’s house and a guest house on the bay. The State of New Jersey purchased Island Beach in 1953 and opened the state park in 1959. All facilities at IBSP, with the exception of the Gate House, are currently served by individual subsurface sewage disposal systems (septic systems). Records indicate that the Park Police septic system was built in 1932, Ocean Swim Area 1 septic system was constructed in 1960, Ocean Swimming Area 2 septic system was constructed in 1962, and the Gate House was connected to the sanitary sewer in 1968 via a sewer ejector station, a low-pressure system.
DPMC and NJDEP-DPF needed to address the future wastewater needs at IBSP via the collection, conveyance, and off-site treatment of sanitary sewage from this environmentally significant barrier island resource.
Based on the water use data presented by the DPMC, and subsequent data obtained by Shore Water Company, the peak months of visitation to the Park are June (17.6%), July (33.3%) and August (21.2%) or 72.1 percent of the total yearly visitors. The majority of the wastewater flow is generated by Ocean Swimming Area 1, Ocean Swimming Area 2, and the Park Office. Based on actual water use data during the initial design phase of the project, mid 2015, the flows had not changed significantly over the previous four years.
In order to convert quarterly water use data into projected wastewater flow, the data needed to be analyzed over the period of expected actual usage. Since the swimming facilities have limited use other than during July and August, and on weekends/holidays in June and September, the water consumption data for that period was divided by 78 days and then considered to be generated over an eight-hour day. Therefore, the design of the proposed sewage system was based upon an average flow of 50 gallons per minute, with an estimated peak of 200 gallons per minute using a peaking factor of four.
An important consideration in the design of wastewater collection and conveyance systems is future growth and/or increased wastewater generation. The project team’s understanding of the project was that no significant increase in wastewater generation was expected. That said, the system design was able to accommodate modest flow increases in the future due to increased visitor capacity or changes in use.
The basis of design was to provide sewer service to the following locations:
A – Interpretive Center Coast Guard Station No 112 (has an average of 30 visitors per day all year long),
B – Fisherman’s Walkway, Lot 7
C – Governors House, (6 bedrooms, 200+(150 x 5) = 950 gpd based on septic regs);
D – Bay House, (4 bedrooms, 200+(150 x 3) = 650 gpd based on septic regs);
E – Freeman House, (4 bedrooms, 200 +(150 x 3) = 650 gpd based on septic regs);
F – Park Police, (open around the clock, max of 4 officers – 4 officers x 10 x 3 = 120 gpd)
G – Maintenance Yard, (seven full time employees, and 30 seasonal employees), (34 employees x 10 +5 showers = 510 gpd); and
H – Entrance Gate House, (staffed round the clock, and reported to be on an ejector pump to the Berkeley Sewer System for conveyance to the Ocean County Sewerage Authority Berkeley Plant).
The nature of the Park, being highly utilized during the summer months, with little usage during the winter months, combined with its flat topography and sensitive environmental features created significant issues related to the design and operation of a wastewater conveyance system. Since in this situation, gravity flow of wastewater was not possible and therefore pumping was required, there were considerable issues with storage and pumping of such varying flows. In addition, the other facilities within the park generating minimal wastewater presented further design challenges.
In conventional pumping station/force main, wastewater is collected in wet wells and then pumped in cycles through small diameter force mains. Important criteria in the design of these facilities were wet well sizing and detention time. Other key considerations were force main velocity and the maximum time that wastewater will remain within the force main before it is discharged.
Pump station/ force main sizing is relatively straight forward when wastewater flows are consistent. On this project, the inconsistent, seasonal flows resulted in extremely long detention times in both the wet wells and the force mains. The concern was that wastewater not exposed to oxygen would quickly become septic. Wastewater becomes septic when anaerobic biological activity (i.e., in the absence of oxygen) consumes organic material, sulfur, and nitrogen found in the wastewater resulting in odorous compounds. To make matters worse, one of these compounds, hydrogen sulfide, forms sulfuric acid which is highly corrosive.
The New Jersey Administrative Code that regulates sanitary sewer design (N.J.A.C. 7:14A-23) requires wastewater pumping stations and force mains to be provided with;
• Two power sources;
• Flood protection;
• Positive Ventilation;
• Flow Measurement;
• A force main cleansing velocity of at least 2 feet per second;
• Air Release valves for high points of a force main;
• Electrical conduit seals between wet well and control center;
• Winch and guild rails for lifting submersible pumps from wet well;
• Less than 10-minute detention time of wastewater within the wet well; and
• Inlet screens to filter material from the wastewater flow to protect the pumps from clogging.
To illustrate the design challenges discussed above, conveyance of the combined sanitary flows from the 2 Ocean Swimming Areas and the Park Office to the existing sewer near the Gate House at the North end of Island Beach State Park required approximately 21,200 feet of force main pipe. A 4-inch force main pipe of this length will hold approximately 13,702 gallons of wastewater. Reduction in the size of this line would reduce the overall amount of wastewater in the line (e.g., a 3-inch diameter line would hold approximately 7,785 gallons, a 57 percent reduction in volume). This volume is important, as will be discussed below.
During the peak flow months (summer), wastewater would be “changed” in the force main 1.2 times per day for a 4-inch line and 2.25 times per day for a 3-inch line. During the low flow months, (January, February, March, October, November December) where flow can drop to as little as 190 gallons per day, wastewater would remain in the force main for the entire off season. This wastewater would become anaerobic (septic) and generate hydrogen sulfide gas which is odorous and results in highly corrosive sulfuric acid when it condenses on surfaces within the system. In addition, because of the extremely long detention time, solids will tend to settle in the force main. These solids could eventually result in force main blockage.
The long detention time issues can be mitigated for the most part through a combination of ventilation, odor control, chemical treatment of the wastewater, special coatings and material, and modified operational procedures. However, all of these will add capital and operation & maintenance (O&M) costs to the project. For example, stations to launch and retrieve cleaning “pigs” may be necessary to keep the force main clean. Chemical feed facilities could be required at strategic locations. The system would also require special pressure manholes to monitor and provide emergency access. High points in the force main would require air release valves which would also require vent stacks to remove any trapped air or gases, resulting in the dispersion of odors.
Regarding chemical treatment, there are several methods of treating the wastewater within the force main to combat the wastewater turning anaerobic which would be evaluated for the project specific conditions. The use of any of these methods would require the construction of significant facilities, and potentially, the storage of a significant volume of chemicals within the pristine Park environment. These methods include:
A – Bioxide – is widely used, however it is relatively expensive and would require an above ground storage tank and feed system to be located at the injection points.
B – Oxygen – injection into the wastewater stream, to maintain the oxygen for the microbes and keep them from going anaerobic, is also used however the time of detention during low flow months would also require multiple injection points.
C – Nitrate – available in both liquid and dry forms can also be injected to replace the sulfate action of the bacteria. Nitrate is consumed up to 15 times slower than dissolved oxygen within the wastewater. System requires a storage tank, metering pumps, valves and piping. Application parameters are case specific and dosage requirements should be verified by pilot studies before implementation.
D – Chlorine – is available as pure gas and hypochlorite liquid. Chlorine gas requires a small amount of space but has safety issues associated with its storage and use. Hypochlorite requires a storage tank, and metering pumps, requiring more space, but is safer to use. Bench testing would be required to determine how chlorine will react under project specific conditions and what chlorine byproduct issues would be created.
E – Hydrogen Peroxide – is available in liquid form, reacts with sulfides in the wastewater and typically lasts for 90 minutes of retention time, requiring multiple application points along the force main. Once the hydrogen peroxide is used up, sulfide returns to previous levels. Safety equipment and wash down equipment are required for the handling of the chemical. Because of the cost and reactivity, it is seldom the least expensive chemical addition, however it does have applications in low flow anaerobic waste streams.
The force mains were designed to be installed by either of two means; open cut or by directional drilling, with bid items for both. Directional drilling was a good option on this project based upon site conditions which resulted in lower construction costs and lesser environmental and social impacts.
Our scope of services included a study which determined that the collection and conveyance of sanitary wastewater from the main facilities on the north and central sections of IBSP would provide the greatest benefit. The following are among the alternatives that were considered to manage wastewater flows generated within the Park.
1 – Vacuum sewer system and dry pit submersible pumping system.
2 – Conventional pumping stations.
3 – Conventional pumping stations combined with satellite ejector stations (low pressure).
4 – New septic systems for the Ocean Swimming Areas and the Park Office, and new toilet facilities to reduce wastewater treatment requirements, with potential use of recycled (gray) water for the toilets.
5 – Package treatment plant for the Ocean Swimming Areas and the Park Office only and continued septic for the other facilities.
It was determined that the best alternative system was the Vacuum sanitary sewer collection and conveyance system, vacuum lateral connections, two (2) central vacuum collection stations and associated force mains (from the vacuum stations), with eventual discharge to a gravity flow portion of the system at the north end of the Park.
By pulling (vacuum) rather than pushing (pumping) the wastewater through the system, the system will generally remain empty during the extended low flow periods. The central vacuum pump stations were designed to be located at the Maintenance Yard and at the Park’s Office. The main wastewater conveyance lines were designed as be 8 and 6-inch PVC pipe under vacuum, constructed in a saw tooth pattern. The vacuum system was designed to operate as demand required based on flow and to remotely operate from a main PLC, 3 or 4 times a day, to keep the liquid and air flowing through the system even during low flow times to ensure a reduction in septicity and deposition in the lines. The wastewater would ultimately be pumped by a single dry well submersible pump system (also located at the Maintenance Yard and at the Park’s Office) to the gravity sewer system in Seaside Park. A compressor was included inside the vacuum station to blow the force main lines clear of wastewater so that the force main was empty during long periods of inactivity. This would be performed at the end of every day after the Park closes.
The principal benefit of this system is that it minimizes long detention times for wastewater and therefore the opportunity for the formation of Hydrogen Sulfide. It is also readily expandable to include all the structures within the Park. Additional benefits include the fact that backup standby generators located at the Maintenance Yard and at the Office Area (to power the central vacuum and pumping station) will allow the entire system to operate during power outages. Also, odor control and/or chemical treatment facilities would not be required.
The chosen alternative subsequently led to the comprehensive design of this vacuum sewer system which will serve the northern seven (7) miles of the approximately 10-mile-long barrier island. Over a seven-year timeframe, beginning in 2015 and continuing until the project was bid in 2022, through extensive regulatory and environmental reviews, the project team completed the design of the vacuum sewer system including the generation of a Construction Cost Estimate and Contract Documents including Bid Level Construction Drawings, Technical Specifications and a Construction Schedule.
Several rounds of review were conducted by the NJ DPMC, and included Building Code Review, Electrical Code Review, Plumbing and Mechanical Code Review. The construction plans were also reviewed by the Ocean County Utilities Authority and the Berkeley Township Municipal Utilities Authority since the wastewater would be discharged to both of these entities.
Since portions of the project were either located within a 500 Year Flood Plain or within a Special Flood Hazard Area, a Flood Plain analysis was required to be conducted, and the system design required the project team to obtain Flood Plain Approval from the NJDEP’s Division of Dam Safety and Flood Control. Additional permitting through the NJDEP Division of Water Quality for the project included a Treatment Works Approval.
The project team also completed an extensive NJDEP environmental permitting effort required due to the significant environmental constraints within the project area. Permits obtained for this project included a Coastal Area Facility Review Act (CAFRA) Individual Permit, a Freshwater Wetlands (FW) General Permit No. 2 (GP2) for the construction of an Underground Utility Line, a FW Transition Area Waiver for a Redevelopment, and a Water Quality Certificate.
The project team maintained an integral part in the bidding process for this over 20-million-dollar construction project which was bid and awarded in 2022. Currently, the project team is participating in the Construction Administration as this project is currently under construction.
• The major win on this project was the removal of septic system discharge from the barrier island. Due to high groundwater and other site-specific conditions, these systems were likely not providing adequate treatment.
• The New Jersey Administrative Code (N.J.A.C. 7:14A-23) does not address Vacuum Sewer Systems. The project team worked closely with the NJDEP to provide the information and assurances necessary to obtain the required Treatment Works Approval.
• By regulation, the Berkley Township Utilities Authority (BCUA) must collect and convey all individual discharges to the Ocean County Utilities Authority (OCUA) for ultimate treatment and disposal. Based upon the size and condition of the BCUA system adjacent to the Park, the BCUA was requiring a replacement of the sewer pipe along 23rd street, which would have been expensive and disruptive to the community. The project team was able to identify and permit a system alignment utilizing an existing fire break easement and an existing right-of-way to avoid the replacement work.
• BTUA and OCUA both had serious concerns about the Park’s sewer system introducing odors and corrosive gases into their systems. Because of this concern, both entities refused to endorse the project which led to a significant delay. The project team designed into the system a number of safeguards to mitigate odor generation and ultimately convinced the BTUA and OCUA to endorse the project.
In addition to utilizing a vacuum sewer system, which in itself if extremely innovative, the project team incorporated the following:
• In order to minimize environmental impacts and streamline the permitting process, the project team designed the system to be constructed utilizing two different methods of “trenchless:” pipe installation technology:
– Direction Drilling (force mains)
– Microtunneling (gravity sewers)
• The project team designed a first of its kind dual chambered vacuum tank system to better handle significant flow fluctuations.
• The project team incorporated Bio-Filter Beds into the pump station building which utilize natural materials (e.g., wood chips) to mitigate odors.