Playing golf above the tree tops in Florida.  Not possible, you say?  Well, Brownfields Properties LLC, a developer based in Atlanta, GA, is constructing a unique golf course and community on 225 acres in Jacksonville, FL, promising that experience.

By Bruce Clark

The golf course is being constructed on and around a 55-acre municipal landfill that opened in 1972 and closed permanently in 1986.  The developer acquired the landfill in 2002 from the original owner, Waste Management Inc.  The course will be 6,800 yards long and will include clubhouse, pro shop, driving range, and golf cart storage and maintenance facilities.  Six of the regulation 18 holes situated on top of the 65-foot–high mound will provide golfers an exhilarating view that will be hard to match anywhere in Florida, or in the southeast, for that matter.

The community, called Edgewater at Sunbeam, is a 134-unit upscale residential enclave adjoining the landfill course on the portion of the property not previously used for waste disposal.  The community sold out before any building construction had even begun.  Getting to the construction of the course required the developer to clear more than the average number of regulatory hurdles.  A brownfield project like this had never been done in Florida.  Golf courses had been built on old landfills before, but those landfills were mostly shallow trench fill sites with no significant vertical relief. 

The landfill itself is not especially unusual as recent landfills go in Florida.  Constructed before regulations required bottom liners and leachate collection systems, the landfill, nevertheless, had not been a source of environmental problems in the area.  Despite the absence of a liner, groundwater quality has met regulatory standards. The landfill was capped with approximately 2 feet of soil and a grass vegetative layer.  The flatter top area of the landfill included a 6-inch–thick layer of a mixture of native sandy soil and powdered bentonite clay under the soil cap that reduced the ability of rainfall to percolate into the landfill. 

The volume of waste in the landfill (estimated at 3.7 million cubic yards), combined with its height, presented special problems for use as a golf course. Successful development of the golf course took the combined efforts of the developer, a golf course architect with prior experience designing landfill golf courses, and consultants with special expertise in the earth sciences; civil, geotechnical and solid waste engineering; and landfill operations and maintenance. 

Some of the challenges unique to the landfill’s planned use as a golf course included:

• Ensuring the long-term stability of the landfill sideslope cap and the underlying waste mass with the addition of up to 17 feet of soil fill for the tee box areas and putting greens.
• Evaluating the potential for the additional settlement caused by the soil fill to push old waste into the water table.
• Preventing irrigation water for the turf from seeping into the landfill, creating leachate and potentially accelerating decomposition and settlement of the waste.
• Ensuring that supplemental groundwater withdrawals from a new golf course water supply well would not result in adverse affects on the groundwater outside the landfill footprint.
• Capturing and managing the disposal of landfill gas and condensate produced from the decomposing waste.  If not properly managed, landfill gas has the potential to damage the turf and create odors and presents an explosion hazard under certain conditions.

Drainage around the toe of the landfill was inadequate, thus contributing to mounding of the water table under the landfill and making some areas of the landfill impassable during the rainy season.

Because of the unique technical issues and lack of precedent, the regulatory permitting process was challenging.  Instead of a long-dormant and almost forgotten landfill, regulators now were faced with the prospect of a site designed to attract golfers and nearby residents to use the new facility.  The regulators required a thorough analysis of potential problems and solutions before granting a modification to the landfill’s existing long-term care permit.

A geotechnical analysis was completed to assess the settlement of the soil under landfill footprint with the superimposed new soil fill.  Geology of the area consisted of sandy soils with the potential for isolated lenses of silt and clay to a depth of about 50 feet.  Below that was the limestone of the Floridan aquifer.  It was estimated that the original settlement of the bottom of the landfill would have been about 1.4 feet, and the settlement from the soil fill added another 5 inches.  Based on accounts of the construction of the landfill, it was anticipated that the old waste at the base of the landfill would still remain at least 3 feet above the seasonal high water table.  Because the landfill had naturally consolidated over the years, the slopes had flattened out to around 6H:1V to 10H:1V, so the added fill did not pose significant short- or long-term stability issue.

The developer elected to manage the irrigation issue with a multipronged approach.  First, only areas of planted turfgrass (i.e., tee boxes, fairways, and putting greens) would be irrigated. 

Out-of-bounds areas of the course would be left in a natural condition and not irrigated. Second, turf irrigation frequency and amount would be based on a careful assessment by the course manager of the rainfall and turf conditions on a daily basis. Irrigation would be conducted only if rainfall was insufficient to sustain the turf grass in a healthy state and to maintain good playing conditions. 

As an additional precaution, the civil engineer specified the use of geosynthetic clay liner (GCL) blankets to be installed under the tee boxes and putting greens.  The GCL blankets will stop irrigation water that might percolate down through the fill and prevent it from penetrating into the landfill waste.  As for the landfill itself, the civil engineer specified spot repairs of the clay admixture barrier under the grass cap where it was determined to have been compromised over the years by excessive settlement.

Prior to acquiring the landfill, the developer had SCS Engineers perform a condition assessment of the landfill gas collection and management system to identify areas of concern and assess what initial repairs were necessary. 

The landfill gas management system consists of 35 vertical extraction wells connected by a looped header pipe system, two gas condensate pumping stations, and a candlestick flare.  SCS found that most of the wellhead components, including hoses, fittings, and throttling valves, were in need of repair and in many cases had to be replaced.  In some cases, the differential settlement of the protective casing around the well left the wellhead sticking up out of the vault, and this also required repair.

Other problems encountered were substantial fluctuations in the flow of gas collected and flared as a result of the landfill being effectively saturated from rains that infiltrated through the sideslopes and areas on top where the clay cap had deteriorated.  This led to the screen sections of several gas collection wells being periodically flooded by the liquid in the landfill.  As a result, the well’s capacity to extract the gas from the landfill fluctuated.  In addition, sections of the gas collection header pipes failed and further impeded the collection system efficiency.  Gas flow to the flare measured around 500 cubic feet per minute (cfm) initially, but fell to as low as about 300 cfm because of the compound effects of these system problems. 

Part of the landfill gas condensate collection system, an 1,800-foot–long gravity pipeline, had experienced significant settlement and did not function.  In addition, the master landfill gas condensate pumping station was plagued by aged equipment that broke down periodically; from pH chemical pumps to the submersible pumps used to discharge the condensate, after neutralization, into the sewage force main interceptor system of the municipal utility.  SCS also found that the electrical and control panels had corrosion of most of the components as a result of long-term weather exposure.

Working together, the developer and SCS have systematically gone about repairing or replacing the faulty parts of the system and instituted a periodic maintenance program so that the system meets at least minimum operating standards and regulatory permit conditions.

For the two extraction wells that had experienced consistent flooding, SCS recommended a trial test with solar-powered submersible dewatering pumps, which the developer approved.  The pumps continuously dewater the wells and in lowering the water level below the screened sections, have over the past six months restored the gas collection efficiency to the two wells.  The pumps have performed reliably. 

Once the golf course construction is fully underway, further enhancements to the landfill gas collection system, such as additional extraction wells and more dewatering pumps, will be considered to help ensure that landfill gas is contained within the landfill footprint and odors are not an issue. Other planned upgrades include new electrical panels at the flare and pumps and piping at the master gas condensate pump station.

SCS also prepared plans that indicate the areas of the landfill gas collection system where collection pipes will have to be rerouted and wellheads replaced during the placement of the fill soils.  To prevent failure of the pipe under the increased settlement and vertical load of the soil fill, SCS recommended that any area where soil fill would be more than 2 feet thick should have the pipes removed and rerouted either around or through the fill at a normal burial depth.  The existing wellheads that would otherwise be buried under new fill will be removed and new casing pipe extended vertically, the new soil fill placed, and new wellheads installed in new vaults.

To deal with the drainage problems at the toe of the landfill, the civil engineer designed a positive drainage ditch around the perimeter of the landfill to efficiently route storm runoff from the landfill to a large retention pond system. 

Actively managing the landfill runoff reduced the mounding effect of the runoff on the water table to an insignificant level of concern. Water supply for the golf course is taken first from existing, onsite lakes, then from the shallow aquifer, and finally as a last option from the Floridan aquifer, the deeper of two aquifers in the region, which is separated from the shallower surficial aquifer by the sandy clays.

A computer simulation of the hydrogeologic regime was conducted to assess the overall interaction of the site drainage, the new potable well for the course irrigation, groundwater in both aquifers at the site and the new stormwater runoff retention ponds. The simulations indicate that the site water management scenario is unlikely to have an adverse effect on the site groundwater quality or to significantly interrupt the existing groundwater flow conditions at the site.

The developer is scheduled to move forward with full construction of the golf course on the landfill later this year, with seeding of the turfgrass to be conducted in the spring dry season.  The course should be ready for play in the fall.  MSW

Bruce Clark, P.E.,DEE, is a project director with SCS Engineers in Tampa, FL.

MSW - May/June 2006