Every Drop Counts

Holly Springs’ growing water reclamation program saves potable water costs and reduces discharge into a local creek.
Every Drop Counts
The Town of Holly Spring WRF team includes, from left, Kai Vannoy, senior operator; Jennifer Exum, lab technician; Jeff Peters, reclaimed water coordinator; and Terry Foster, senior operator.

Since 2010, the Town of Holly Springs, N.C. has been operating its wastewater treatment plant as a water reclamation facility, treating the sewage to less-than-potable standards for use in irrigation and industrial applications. The town distributed approximately 40 million gallons of reclaimed water in 2012, saving $75,000 in potable water purchase costs and reducing the environmental impact of discharging water into nearby Utley Creek.

As a bedroom community 20 miles outside of Raleigh and near several universities, Holly Springs has seen steady population growth in the past two decades. In the late 1990s, the town council proactively planned improvements to the tertiary wastewater treatment system in anticipation of higher demand. While planning the upgrades, the town wanted to reduce its discharge into the creek, and started considering a water reclamation program.

"There has been a move in North Carolina for more sustainable solutions to water usage, and reclaimed water has started spreading across the state," says Jeff Peters, reclaimed water coordinator. "More municipalities are picking up on it. The town saw how well it was working in Florida where water is really limited and there was a good utilization of reclaimed water."

Holly Springs' original reclaimed water master plan was developed in 2000, but was shelved until the town could secure a large enough user to justify the system. In anticipation, the town began collecting a fee for all new development that would be added to the water reclamation fund. Eventually, Holly Springs Business Park and The Club at Twelve Oaks golf course and residential community came on board.

Building a system

In October 2009, Caldwell Tanks began construction on a 500,000-square-foot steel-over-concrete elevated storage tank located in an industrial park a half-mile from the reclamation facility. T.A. Loving installed 2.8 miles of reclaimed water distribution lines, and the system went live in July 2010. Holly Springs became the fourth, and smallest, town in North Carolina to start a water reclamation program, and the second town in the state to offer reclaimed water for residential use.

The $2 million project was partially funded by a $750,000 State and Tribal Assistance Grant from the North Carolina Department of Environmental and Natural Resources Division of Water Quality (DWQ). The remainder was funded through development fees.

The reclaim distribution system goes through the Holly Springs business park, which is near Novartis and The Club at Twelve Oaks, a 687-acre golf course and residential community. The development uses reclaimed water to irrigate 40 percent of its golf course and the residential landscaping.

In addition, the town uses reclaimed water for irrigation along the landscaped medians in the business park and for on-site operations at the reclamation facility. A new shopping center currently under development will be the next customer to use reclaimed water for irrigation.

During the hot months, the Novartis cooling tower peaks at up to 5 million gallons of reclaimed water usage per month, and Twelve Oaks uses 1.5 million gallons per month. In the winter, demand for reclaimed water is minimal. During the first full year of the system's operation, the town distributed 19.5 million gallons of reclaimed water, which more than doubled to over 40 million gallons the following year.

Users of reclaimed water save up to 66 percent on their water bill compared to the usual $7.50/1,000 gallons for potable water. Reclaimed water for irrigation costs $3.75/1,000 gallons, and industrial users pay $2.50/1,000 gallons. The reclaimed water charges show up on the same bill as water, sewer and trash.

Holly Springs makes little profit from the sale of the reclaimed water because costs are slightly higher than just discharging water into the creek. Reclaimed water is treated above typical wastewater standards. However, unlike the water discharged into Utley Creek, reclaimed water requires an additional treatment step — disinfection with sodium hypochlorite — before going into the elevated storage tank. The town's cost savings are generated from the reduction in drinking water it purchases from a nearby municipality.

The current distribution system is limited to a small area, but the goal is to expand it further. Town engineers are investigating the feasibility of using abandoned force mains throughout town to deliver reclaimed water to a larger area.

"There are other potential high-volume users developing in town that would also benefit reclaimed water, so they are looking at possible ways to get that water to them," says Kai Vannoy, senior operator at the water reclamation facility. "The town is well-developed, so it's not easy to install a new distribution line in neighborhoods. It would be burdensome for the residents and not very cost-effective for the municipality. The abandoned lines are already installed in the ground, so that would be the most cost-effective way to do it."

Avoiding cross contamination

There are challenges in maintaining two separate water distribution systems. To reduce confusion, Holly Springs has water responsibilities separated into two groups: Public Works handles drinking water distribution and sewage collections, while Public Utilities is responsible for treating wastewater and distributing reclaimed water.

Construction of the reclaimed water pipeline was guided by several state codes and statutes. Reclaimed water standards set by the DWQ require all reclaimed water pipes to be marked with a Pantone 522 light purple color and labeled "Reclaimed water. Do not drink."

"The biggest thing is making sure the systems are clearly marked," Peters says. "When going out to shut off a valve, we want to make sure we're shutting off the right line, whether it's reclaimed or potable."

The street valve lids for reclaimed water are square and painted purple to stand out against standard circular drinking water valve lids. Separation distances between the reclaimed water line and the sewer and potable lines must be 10 feet horizontally and 18 inches below the water line to avoid cross-contamination.

Above-ground hose connections for reclaimed water are not allowed. There can be no direct cross-connections if there are potable and reclaimed water in the same location. For instance, in a cooling tower, there must be an air gap separation between the piping to ensure no reclaimed water goes into the potable line.

To further prevent cross-contamination, all parties who install or maintain reclaimed water are required to go through training conducted by the Holly Springs Public Utilities group, as regulated by the DWQ permit.

Before beginning a new irrigation installation, the town's engineering department checks out the contractor thoroughly to ensure proper qualifications and training. Holly Springs development inspectors and plumbing inspectors make sure piping and meters are connected properly throughout the building process.

Buying in bulk

Holly Springs began a bulk reclaimed water program in October 2012 for customers to get free reclaimed water if they pick it up themselves. The DWQ permit requires all reclaimed water users to be trained and licensed to ensure proper use, such as limiting runoff into streams and storm drains, and knowing where use is prohibited. Peters conducts the training himself.

The bulk system, installed as part of the larger plant upgrade, includes a storage tank, pump station, meter and tracking system. Users swipe a keycard before filling so the town can keep track of who is using the water. A gas pump-like system is set up for filling smaller tanks, and an overhead boom with a 4-inch pipe can be used for larger tanks. The bulk filling area is located on the reclamation facility site and is open during weekday business hours.

Potential uses for bulk water include hydroseeding, landscape irrigation, makeup water for brine slurry, sewer jetting, concrete makeup water and dust compaction on construction sites.

"We are gradually making people aware this bulk water is available," Peters says.

Reducing creek discharge

Although the water reclamation program is saving the town money by reducing the volume of water requiring treatment for potable purposes, another motivator has been reducing water discharge into Utley Creek.

"Environmental stewardship is one of the biggest benefits to the reclamation system," Vannoy says. "North Carolina is prone to drought conditions, so we are helping to foster more sustainable practices. We can reuse this water rather than putting it back into the creek."

Studies are currently underway to measure if the reclamation program has had a positive impact on nearby waterways, such as reducing nutrient loads.

Discharging less water into the creek also helps Holly Springs with its National Pollutant Discharge Elimination System permit from the state, which dictates how much water can be discharged from the treatment plant. The town stays well within its discharge limits by diverting some water to reclamation.

"Each gallon of reclaimed water used saves a gallon of potable water that can be used for cooking, drinking and human consumption," Vannoy says. "Thus, the community spends less on the cost of potable water and extends the availability of water for future generations in an environmentally acceptable and friendly way."

Maintaining a Reclamation System

Maintenance of the reclaimed water distribution system is ongoing, but fairly simple for senior operator Kai Vannoy and the rest of the Public Utilities staff.

The team uses information from a SCADA system to perform constant distribution checks for large spikes in the meters, which may indicate a line break or leak. The staff conducts monthly water sampling throughout the distribution system to check for turbidity levels, nutrients and chlorine residuals. Valves are tested and exercised annually to ensure they are working properly, and the elevated storage tank is cleaned every two years by an outside contractor.

The Public Works group performs all repairs on the reclaim pipeline because it has the labor force and heavy equipment necessary and has procedures for cleaning and sanitizing equipment to avoid cross-contamination.


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