By Christopher A. Weiss and Timothy N. Nordberg
Why would H2M architects + engineers (H2M) and the Town of Riverhead improve upon a perfectly functioning wastewater treatment plant and pave the way for new concepts like “wastewater reuse”? When the wastewater facility is situated on a sole source potable water aquifer and a nationally significant ecological estuary. It also helps when you are lucky enough to have an environmentally forward-thinking municipality that embraces innovation for the overall benefit of the region. Reusing wastewater on Long Island is an idea that has been overlooked for too long. Creating the first municipal reuse facility in New York was the perfect solution to address this unique combination of circumstances.
Project Challenges and Solutions
The existing 1.3 million-gallon-per-day (MGD) Town of Riverhead Advanced Wastewater Treatment Facility (AWTF) in Suffolk County was last upgraded in 2000. The AWTF regularly met its total nitrogen discharge limit of 15 mg/1 to the Peconic River. In 2001, recommendations from the Peconic Estuary study (Peconic Estuary Program 2001) included reducing nitrogen loading by all sources to strengthen and maintain the estuary for the future. This recommendation coincided with the sewer district’s consideration that a portion of their effluent could be reused as irrigation water on the neighboring Indian Island Golf Course to reduce the nitrogen loading to the Peconic River.
What seemed like straightforward application idea was found to be all but simple. New York did not have state standards in place for wastewater reuse for irrigation discharge. So, H2M and Riverhead had to conduct a research study to determine what the standards would be, prove the standards could be met, and get the standards approved by the regulating agency – all before the project could move the full-scale design phase. The research study collated all the reuse water standards from states across the country already applying reuse water and selected the strictest of each parameter to be monitored in the discharge. Then, a pilot plant was designed and constructed on the AWTF property. A portion of the existing plant’s tertiary effluent was passed through the pilot plant for additional treatment to meet these stringent reuse water standards. To test the water from reuse pilot plant, a replica golf course hole was constructed on the AWTF property using the same soils, grasses, and landscaping as the Indian Island Golf Course. Testing was conducted on the water from the sprinklers as well as on the replica golf course landscaping, soil strata and air.
Successful completion of readily available treatment equipment on typical tertiary AWTF effluent to meet the newly formed reuse water standards has set the path for other projects in New York to follow. However, just as the reuse standards derived by this project were being approved by the regulating agency, the New York State Department of Environmental Conservation (NYSDEC), in line with US Environmental Protection Agency’s (USEPA) estuary recommendations, modified the facility’s State Pollutant Discharge Elimination System (SPDES) permit to a lower effluent nitrogen concentration, from 15 mg/1 to 3.2 mg/1.
To meet the lower effluent nitrogen limit the entire treatment facility would be upgraded. The wastewater reuse project initially planned as an extension to the existing wastewater treatment facility was now re-designed to be an integral part of a full facility upgrade. The new Riverhead Water Resources Recovery Facility (WRRF) project blossomed to cost $24 million which included a 1.5 MGD membrane bioreactor and reclamation system with a fully integrated wastewater reuse process train and golf course irrigation supply system. Ultrafiltration membrane technology used in the main process treatment train was selected based on its ability to produce crystal clear effluent on a consistent basis prior to final disinfection. This eliminated discharge clarity impacts on the Peconic River, resulting in plant effluent that is always reuse-ready. That was the heart and soul of this project.
Water Resource Recovery Facility Design
The new facility was designed with the environment in mind. Existing structures, including concrete tanks and operations buildings, were repurposed. Energy efficiency measures were selected, such as variable frequency driven motors, in-tank probes for real-time process monitoring and motion sensors for lighting. These efficiency measures reduced the overall carbon footprint for the construction and future operation. Permit limitations in place during dewatering operations ensured that no pollution would occur in the tributary creek adjacent to the site, which ultimately flows into the Peconic River. Trenchless directional drilling techniques were used to install the 1,000 feet of force main piping under the golf course, from the facility to the irrigation control building. This approach eliminated the costly rehabilitation of fairways, tees and greens.
To provide consistent results from a complex plant capable of meeting the limits of today’s technology, H2M used techniques to provide the “simpl-exity” needed to simplify the complex nature of the operations. Using wireless connectivity between the facility and the golf course, as well as fiber optic cables between process control panels on the site, a site-wide SCADA loop was created for total controls, with remote access built in for viewing the process from anywhere. More reliable sensors also allow for real-time process control abilities, further promoting energy efficiency and control over the treatment operations.
New York State’s First Municipal Reuse Facility
The Town of Riverhead WRRF is the first municipal reuse facility in New York State and was completed in time for the 2016 golf irrigation season. The project was completed within budget, which included New York State and Suffolk County grants of $2 million and $8 million, respectively. The new facility was upgraded with biological reactors matched with ultrafiltration for solids/liquid separation and ultraviolet disinfection to meet the limits of today’s technology. These processes were chosen to both consistently meet the Total Maximum Daily Load for Total Nitrogen levels for discharge to the Peconic River, and to stay within the footprint of the pre-existing plant. The limitations of the new SPDES permit will reduce the overall annual nitrogen discharge by over 50 percent from the previous limitations.
The Town of Riverhead WRRF will reuse up to 100,000 gallons of in-plant washwater and makeup water each day for internal treatment facility equipment. Potable water traditionally has been purchased from the local supplier for this purpose. The benefits of the internally recycled water include reduced groundwater demand for the local potable water treatment plant and additional control over water pressure with the addition of a single booster pump.
The Town of Riverhead WRRF also provides up to 450,000 gallons per day of reuse water for normal sprinkler irrigation to the adjacent Indian Island Golf Course, free of charge. This irrigation water no longer needs to be drawn from golf course groundwater wells and is sufficient to provide all the water they need on a typical summer watering cycle. Reuse water containing minimal nitrogen will replace the iron-rich well water that interfered with the mechanical operations of the irrigation valves and sprinkler heads. It will also provide additional nutrients to the fairways, tees and greens that reduces the need for traditional fertilizer application. By reducing the draw on the groundwater aquifer, the groundwater level that exists will continue to protect against the intrusion of the surrounding salt water bodies. A truly outstanding result of the project was the community acceptance by the residents, the golf course patrons and the grounds crew, pushing past the fear of wastewater reuse and joining the chorus of … “It’s about time.”
The upgraded facility, with its Water Resource Recovery components online, will enhance these benefits to the overall well-being of this coastal community by both diverting an additional one-third of the permitted total nitrogen discharge during irrigation seasons away from the plant’s Peconic River outfall and by saving up to 100 million gallons a year of groundwater pumped from the aquifer.
These are realized annual benefits to the Peconic Estuary and Groundwater Aquifer Benefits
- 50% reduction of Total Nitrogen discharged to the waters of the Peconic Estuary
- 90% reduction in suspended solids discharged to the waters of the Peconic Estuary
- 100 million gallons of groundwater saved
In New York State, WWTP flows are in excess of 3,561 million gallons per day. Reusing only 20% of that water resource saves over 260 billion gallons per year from potable water supply. That is over 700 million gallons per day of untapped water resource recovery potential.
On the Horizon for Wastewater Reuse
Biosolids reuse is the next sustainability target that H2M will be assisting the Town of Riverhead with at their wastewater treatment facility. The treatment facility produces over 1 million pounds of waste solids that removed from the sanitary waste stream. These waste solids (biosolids) are processed further to remove 80% of the excess water and then trucked out of state for landfill disposal at annual cost in excess of $500,000. Beneficial reuse processing upgrades at the plant would increase the water removal to 95% and allow the biosolids to be reused as fertilizer by local farmers, or fertilizer suppliers. This reduces volume of material being trucked off site. The final biosolids material can be used as a fertilizer replacement, and not have to pay for landfill disposal. This sustainability project has the potential to reduce the overall annual waste disposal cost by more than 75%.
Christopher A. Weiss, P.E. is the Deputy Division Director of Wastewater Engineering at H2M architects + engineers and may be reached at firstname.lastname@example.org. Timothy N. Nordberg, P.E. is Project Engineer with H2M architects + engineers, and may be reached at email@example.com.
Peconic Estuary Program. 2001. Peconic Estuary Comprehensive Conservation and Management Plan. 866 pp. Sponsored by the US Environmental Protection Agency under Sec. 320 of the Clean Water Act. Suffolk Country Department of Health Services, Program office.
This article was originally published in the Summer of 2017 in Clear Waters magazine (Vol. 47, Issue No. 2), the official publication of the New York Water Environment Association, www.nywea.org .