Contractors building a 27,000-square-foot estate on Indian Creek Golf Club Island in Indian Creek, Fla., didn’t know the onsite system should be one of the first components installed, not the last. When Jason Nesenman of Jason’s Septic Inc. in Miami arrived to start work, the estate was three-fourths completed.

Although the system’s design was elementary, it was the largest Nesenman had installed to date. He and his five men faced tides, shifting sands, limited access, congestion, a bridge with weight restrictions, and damage to the system that stretched a normal two-week job into a month-long adventure.

Site conditions

Soils were 100 percent sand with no absorption rate, and the water table was 7 feet below grade. The 0.4-square-mile island is in Biscayne Bay, across from Miami Beach. The lot, developed to its limit, is 400 feet long with 500 feet of oceanfront.

System components

Based on 24 bedrooms, engineers at Doug Winters Companies Inc. in West Palm Beach, Fla., designed the wastewater system to handle 2,800 gpd. Its major components are:

• 5,000-gallon cylindrical lift station with two 1-hp Barnes pumps from Southern Pump, West Palm Beach, Fla.

• 2,500-gallon primary septic tank. All tanks from Sebring Septic, Sebring, Fla.

• 1,250-gallon secondary septic tank with two A600 effluent filters from Polylok Inc., Wallingford, Conn.

• 2,500-gallon pump tank with two 1-hp Barnes pumps.

• 1,000 feet of 1-inch Schedule 40 PVC low-pressure pipe.

• Two Hydrotek 6603 multizone distribution valves from Quanics Inc., Crestwood, Ky.

• Control panel from SJE Rhombus Controls, Detroit Lakes, Minn.

Laundry system components

• 1,500-gallon septic tank with A600 effluent filter.

• 200 feet of 1-inch Schedule 40 PVC pipe.

System operation

A 6-inch gravity sewer sends wastewater into the 6-foot-diameter, 12 1/2-foot-tall lift station. Pumps elevate the sewage 12.5 feet to the primary septic tank, from which it flows into the secondary tank and pump tank. Activating 4.5 times per day, alternating pumps in the pump tank push 302 gallons through 2-inch Schedule 40 force mains in 42 seconds. Hydrostatic valves determine which of two 1,500-square-foot drainfields receive the dose. Separated by 10 feet, each bed has 11 laterals.

Laundry water flows by gravity into the septic tank, then to five laterals in the 12- by 41-foot drainfield. All laterals are 38 feet long, on 3-foot centers, and sleeved in 4-inch Schedule 40 PVC perforated pipe.

Installation

Before Nesenman arrived, the building contractor hauled in 200 truckloads of fill to raise the elevation for the house. “He didn’t realize that I had to haul it all out and bring in 20 truckloads of silica sand for the drainfields,” says Nesenman. The bridge from Miami Beach to Indian Creek Island was structurally sound but had a 20-ton limit. Nesenman’s tandem-axle dump trucks weighed 35 tons fully loaded. The Department of Transportation said he could carry only half loads. “That doubled my trips, and heavy earthmoving equipment couldn’t cross the bridge either,” he says.

The men used a mini-backhoe and shovels to excavate the native sand from the drainfield sites. The problem was where to stockpile the sand and fill. “They were starting to landscape and plant mature palm trees,” says Nesenman. “One contractor building the seawall was pulling out fill and bringing it back in. Three backhoes were in constant operation. One was mine. We’d make a pile, then haul it away or move it whenever someone wanted to do something.”

The drainfields were 6 feet above grade. After removing the native sand, Nesenman put 12 inches of prewashed No. 4 ballast rock on top of 42 inches of silica sand. The men drilled 1/4-inch holes every 9 feet in the low-pressure pipe, then sleeved it in 4-inch perforated pipe.

They used the backhoe to cover the pipes with 4 inches of gravel, then topped it with 3-mil fabric-fiberglass mesh and backfilled with 8 inches of native sand. Golf course grass planted on the drainfields will aid evapotranspiration and prevent heavy rain from washing away the sand. The men repeated the process for the laundry drainfield.

About 2 feet of seawater rushed in as they excavated holes for the tanks. “My pump truck couldn’t keep up, so I rented a 4-hp pump and shifted the water to the other side of the building,” says Nesenman. “As fast as we pumped it out, it came back in.”

Working late at night when the tide was low provided the solution. But then the walls of the holes kept collapsing. It also was difficult to spot the installed storm drains before hitting them. A normal 12- by 6-foot pit became a 20- by 30-foot excavation. “As we sloped back, we exposed the bases of the columns and pillars holding up the mansion,” says Nesenman.

In one night, the men set the two-piece concrete septic tanks using two 10-ton cranes, one to lift the halves off the ground, and one to pull them upright in the hole. Each section weighed 16,000 pounds. The Category 4 single-compartment tanks have 6-inch-thick walls and traffic-bearing lids to compensate for the walkway and tennis courts above them. Risers were installed flush with the ground and covered with a hatch.

Nesenman fought two nights to install the pump tank. “Everything kept collapsing,” he says. “I was ready to get a trench box the next morning, but suddenly the tank went right in. Connecting the 6-inch piping took an hour.” The tanks were backfilled with native sand. Nesenman then waited two weeks for the lift station to be manufactured.

Meanwhile, the contractor building a barrier wall around the system received the wrong digging coordinates and hit a distribution pipe in the drainfield, the pressure pump and associated piping. “We replaced those components, but it was a pain ensuring that no sand entered them,” says Nesenman.

Maintenance

Jason’s Septic holds the two-year maintenance contract. “Those 24 bedrooms mean lots of parties with extra toilet paper, so I figure the effluent filters will clog every six months,” says Nesenman. “Maintaining them will provide the opportunity to inspect the pump floats, the only moving parts on this system.”

The design engineers stated that backflushing wasn’t necessary and made no provisions for backflow prevention. Nesenman’s inspec-tion will scrutinize these areas and make sure water isn’t infiltrating and saturating the drainfields.