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Fresh Kills Landfill: Staten Island, NY

  

The following case study was prepared by Exeter Supply Company in Reading Pennsylvania in 1996. The information remains pertinent. A PDF version on the entire report can also be downloaded.

INTRODUCTION

The Fresh Kills Landfill located on Staten Island, New York, is approximately 3,000 acres in size and is the largest landfill in the United States (refer to Figure 1 for a map showing the regional location of the project site). Stone & Webster Engineering Corporation (SWEC) is currently (March 1996) supervising and managing the construction of a Leachate Mitigation System at the Fresh Kills Landfill, on behalf of the City of New York Department of Sanitation. The Leachate Mitigation System at the landfill is to consist of a leachate (groundwater) collection, distribution and treatment system. A “relatively” high elevation of the water-table aquifer at the project site hindered the construction of a leachate treatment plant; hence, a de-watering system was installed to lower the elevation of the water-table aquifer. The Multi-Flow Drainage System was installed by SWEC as a primary component of this de-watering system. The following text includes a summary of the Leachate Mitigation System, a description of the installation of the Multi-Flow Drainage System, performance results of the Multi-Flow, and conclusions regarding the use of the Multi-Flow Drainage System for de-watering purposes.

LEACHATE MITIGATION SYSTEM

A Leachate Mitigation System (LMS) is currently being installed at the Fresh Kills Landfill site. The LMS consists of a system to collect, distribute and remediate contaminated groundwater (leachate). Construction of the LMS will be completed in phases: Phase I, a leachate treatment plant has been completed; Phase II, the expansion of an existing leachate treatment plant, is currently under construction. Expansion of the existing leachate treatment plant had been hindered by a “relatively” high elevation of the water-table aquifer. The elevation of groundwater at the construction area was approximately two (2) + feet above land surface. To lower the elevation of the water-table aquifer at the construction area, SWEC proposed a de-watering system. The de-watering system was designed to reduce the elevation of groundwater at the area of construction to below land surface; and hence enable the construction of the new treatment plant. Stone & Webster Engineering Corporation proposed a traditional crushed stone drainage for the de-watering system; however, upon learning of the Multi-Flow Drainage System, SWEC chose to install Multi-Flow. Refer to Exhibit A for correspondence between SWEC and Multi-Flow Systems, Inc (dated October 7, 1994) regarding the decision to install the Multi-Flow Drainage System.

INSTALLATION OF THE MULTI-FLOW DRAINAGE SYSTEM

In March, 1995, Stone & Webster Engineering Corporation installed the Multi-Flow Drainage System along the perimeter of the treatment plant construction area. The Multi-Flow was installed to a depth of five (5) + feet below land surface (refer to Figure2 for a schematic showing the location of the Multi-Flow and other pertinent features). Two (2) parallel 1,800 foot lengths of 18 inch Multi-Flow were installed at the north and east perimeter of the construction area (refer to Figure 2). During installation, the groundwater elevation was approximately two (2) + feet above land surface; the Multi-Flow was placed within a wire structure and submerged within a trench to a depth of approximately five (5) + feet below land surface. The trench was subsequently infilled to land surface with crushed stone. (*note: Multi-Flow Systems, Inc recommends the use of coarse sand as backfill material; crushed stone was used by SWEC at the project site due to difficulties of infilling the trench with sand through seven feet of water). The gradient of the drainage system trends from west to east, and after a 90 degree turn, from north to south to the discharge point (refer to Figure 2 for groundwater flow directions). Groundwater which enters the Multi-Flow discharges to a concrete sump; when the water level within the sump approaches the elevation of the discharge point, two (2) pumps automatically activate to distribute the groundwater to the existing treatment plant for remediation.

PERFORMANCE RESULTS OF THE MULTI-FLOW DRAINAGE SYSTEM

The Multi-Flow Drainage System has been operating at the Fresh Kills Landfill for approximately one (1) year (between March 1995 and March 1996). Flow rates within the Multi-Flow range between 1,260 gallons per day (GPD) and 39,000 GPD; the average flow rate within the drainage system is between 12,000 GPD and 24,000 GPD. Refer to Exhibit B for flow rate data provided by SWEC. According to SWEC personnel, the efficiency of the system has not decreased since startup of the de-watering system. The flow rate of the drainage system decreases as the elevation of the water-table aquifer stabilizes; as the elevation of the water-table aquifer rises, flow rates through the system increase. As evidence of the continued efficiency of the Multi-Flow Drainage System, flow rates through the system increased dramatically (from approximately 3,600 GPD to 23,700 GPD in a 48 hour period) after heavy rains in late January 1996. This suggests that groundwater flow through the system is limited only to the elevation of groundwater.

CONCLUSIONS

Stone & Webster Engineering Corporation has installed the Multi-Flow Drainage System at the Fresh Kills Landfill, located on Staten Island, New York. The Multi-Flow was installed as a constituent of a de-watering system to lower the elevation of the water-table aquifer, and hence, to enable the construction of a Leachate Mitigation System. An average flow of between 12,000 GPD and 24,000 GPD of leachate has flowed through the Multi-Flow Drainage System from startup (March 1995) to the present (March 1996). According to SWEC personnel, the efficiency of flow through the Multi-Flow has not decreased during the year of operation. A dramatic increase in flow through the system in late January 1996 (subsequent to heavy rainfall) suggests that flow rates through the system have been limited only to the elevation of the water-table aquifer.