Situated on an environmentally sensitive strip of coastline in North Carolina, Coral Bay Club upgrades and modernizes its aging wastewater infrastructure in order to accommodate membership growth

Focused on providing top-tier services and facilities for its roughly 600 members, Coral Bay Club is a private, member-owned facility where people go to play tennis, sweat it out in a group exercise class, enjoy Sunday brunch and socialize in an inviting setting.

With a prime location on Atlantic Beach, N.C., the facility is everything an oceanfront country club is imagined to be.

Established in 1958, Coral Bay Club is managing many of the typical challenges for aging facilities. Physical structures deteriorate with age and can’t always keep up as the organizations that rely on them grow, expand and modernize. Of particular concern for Coral Bay Club was its wastewater infrastructure, which was put in place more than 60 years ago.

That aging infrastructure prevented the organization from increasing its membership. In 2019, the organization decided it was time for an upgrade.

“The club wanted to add about 100 new members, but in order to do so it had to upgrade its existing wastewater system,” said Michael Clayton, sales manager at AQWA, a wastewater solution provider in Wilson, N.C.

The existing infrastructure comprised a “hodgepodge of tanks, terracotta lines and a drain field,” Clayton said. To add that many new members, the organization had to be able to accommodate a substantial increase in the permitted daily flow.

“Some of the project involved bringing the aging infrastructure up to speed,” Clayton said, “and the other portion focused on expanding the system in order to allow the membership increase.”

To resolve these issues, AQWA worked alongside NPCA member Shoaf Precast and others to fulfill the needs.

Managing the intricacies of coastal work

An Orenco Systems dealer, AQWA operates as a consultant to developers, engineers, soil classifiers and other stakeholders that need help using the AdvanTex® treatment equipment that the company installed for them. The system is a compact and efficient recirculating packed-bed filter.

For the Coral Bay Club project, AQWA worked with the project engineering team to determine the size of the tanks, the treatment system and to “work out the practical details” of the overall project, according to Clayton.

The company also designed and provided the equipment for the subsurface irrigation drain field at the commercial facility, which includes a kitchen and that often hosts large events, including weddings and graduation parties.

To accommodate those events, Coral Bay Club’s new wastewater treatment system had to be able to handle the predicted flow, and all equipment had to meet North Carolina’s treatment standards.

The worksite location was another critical consideration on this project, which was situated in an environmentally sensitive coastal area. As preserving these natural resources becomes a higher priority, any work performed or products installed there must be environmentally friendly.

For this project, the tanks would have to be installed near the club’s building, where the bottom of the excavated hole would be several feet below sea level. This was one of several reasons why precast concrete was selected for the project.

“Wherever the tide is, that’s where the water is in your tank excavation,” Clayton said. “So just as fast as you can pump the water out, it wants to come back in and fill that hole up. Needless to say, the project involved a lot of dewatering.”

The arrival of the precast tanks had to be timed perfectly in order to ensure adequate dewatering and preparation of the excavated hole.

Handled by Quality Septic Services of Newport, N.C., the installation process required careful coordination between the precast delivery drivers and the crane operators. To complete the project, the installer also had to do horizontal boring under the main highway – a process that Clayton said went smoothly. However, some challenges did emerge when the sidewall located outside of a trench box collapsed when one of the 10,000-gallon tanks was being set.

“The weight of the sand pinned the trench box against the wall of the tank,” Clayton said. “That added some time to the project. We were digging out sand well into the sunset hours.”

The sandy soils made the digging process fairly easy, but also created some issues because of their structureless nature.

“Just keeping the tank holes open to be able to set the tanks was probably the biggest challenge from the precast tank installation perspective,” Clayton said.

Precast was the natural choice

Headquartered in Lexington, N.C., Shoaf Precast worked with AQWA to provide one 8,000-gallon septic tank, one 10,000-gallon septic tank and one 10,000-gallon flow equalization tank. Shoaf Precast also made a 5,850-gallon recertification tank that included a 4,000-gallon grease trap plus one smaller, 1,000-gallon dosing tank. The pieces were 11-feet-by-4-feet wide and 21-feet-by-4-feet long and weighed up to 42,000 pounds each.

All of the tanks were made using the precaster’s 10-by-20-foot mold and standard design. The tanks also had to be watertight to ensure that their contents would never leech into the area groundwater.

“Our tank sizing was set up for this type of project,” Vice President Phillip Shoaf said, “but any time the tanks are being installed at a coastal site the high water table, sand and environmental concerns can all create unique challenges.”

For example, Shoaf Precast had to modify its rebar schematics in order to accommodate the project site’s high water table. The modifications included adding more rebar and increasing the size of some of the bars.

Shoaf Precast also had to factor buoyancy calculations into the production process to ensure that no buoyancy issues would arise during seasons when Atlantic Beach’s water table was high.

“The weight of the precast helped us achieve our anti-buoyancy goals compared to options like plastic or fiberglass, where there would have been some significant concerns for sure,” Shoaf said.

The precast manufacturing process was fairly straightforward, but there were some additional logistical obstacles to navigate. For starters, the site is 260 miles from Shoaf Precast’s plant, and all of the tanks were buried in driving areas so they had to be traffic-rated.

“Given the lot’s small footprint, we had to make sure the trucks were staged and that they didn’t just converge on the site all at once,” Shoaf said. “We worked closely with AQWA and Quality Septic to come up with a good plan and we stuck with it. From what we heard, everyone was pleased with the outcome.”

Functioning spectacularly

According to Clayton, Coral Bay Club’s wastewater overhaul was completed within the desired timeframe and met the budget.

“The treatment system is functioning spectacularly and is producing very good effluent,” he said. “I think everyone would agree that it was a success.”

Carteret County representatives also are pleased with the outcome, particularly from the environmental perspective.

“The facility is now putting highly treated effluent into a drip irrigation system where before. Who knows what level of treatment was occurring – or not occurring – for the 60-year-old infrastructure?” Clayton said. “The club was pleased to be able to get the project done not only in its own best interest but also in a very sustainable and environmentally-conscious manner.

A longterm solution

Reflecting on the role precast concrete played in the coastal wastewater project, Clayton said it was the obvious material of choice and that Shoaf Precast was clearly the best company to make the massive tanks.

“We love Shoaf Precast’s tanks, and particularly their very large products,” Clayton said. “We use them a lot in our commercial and large community systems.”

Clayton said Shoaf Precast’s attention to detail and commitment to sticking it out until the project is up and running sets the company apart from other tank manufacturers.

“A high-quality precast tank on a sensitive installation like this is very reassuring to the installer, engineers, owners and regulators,” he said.

“With Shoaf Precast’s tanks, no one ever has any doubt that those products will still be watertight a decade from now. Precasters like Shoaf, who stay onsite until they are certain that the precast tanks are installed properly and are structurally sound and watertight, make choosing precast tanks for a job like this an easy choice.”

Bridget McCrea is a freelance writer who covers manufacturing, industry and technology. She is a winner of the Florida Magazine Association’s Gold Award for best trade-technical feature statewide.