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Landfill Cap/Wetlands Restoration Project
Southern New Jersey
Project Value: $650,000
Environmental Liability Management-Jeff Amant
Phone: 215-794-6920
In August of 2001 Enviro-Air Technologies, Inc. performed a landfill cap/wetlands restoration project that involved the excavation of approximately two thirds of an acre of wetlands that had been filled in with oily glass waste over a period of fifty years.
Enviro-Air was contracted to excavate the material from the wetlands and move it to an onsite landfill. A large part of the excavation area was located between a stream and a tidal river, making the excavation of the material contingent on the tides. At high tide the water level was anywhere from 6 inches below the ground to completely covering the area.
Soil erosion and sediment control measures included the installation of approximately 2500 linear feet of silt fence that was placed around the perimeter of the project area and 280 linear feet of turbidity barrier that was installed in the stream to prevent sediments from being carried out into the river.
The excavation footprint was approximately 31,680 square feet, divided into two excavations, dug to a minimum depth of 3 feet. Both excavations extended below the water table during high tide and therefore had to be excavated and restored during low tide.
The restoration of the wetlands consisted of backfilling with clean sand conforming to a NJDOT I-9 specification to up to one foot below grade. Enviro-Air imported and placed approximately 2,151 cubic yards of certified clean fill and approximately 1,240 cubic yards of topsoil in the wetlands alone. The top 12 inches were backfilled with topsoil conforming to Specification 909.10. The backfilling of these areas was especially challenging due to the intrusion of water. Enviro-Air excavated and backfilled in the same day to prevent the excavation from filling up with water. After the topsoil was put down and special, native, wetlands seeds were planted, a 100% biodegradable, coconut fiber, erosion control blanket was put over top of the area, to hold the soil and seed in place. After the blanket was installed, 50 special wetlands trees were planted and 30 wetlands shrubs were planted.
Approximately 4,000 cubic yards of wet, oily material was placed on the landfill. After the excavated material was put on top of the landfill it was allowed to drain. The material was leveled with a dozer. Twenty thousand cubic yards of I-9 backfill was imported and put on top of the contaminated material as a cap. After placement and compaction of the backfill, 4,000 cubic yards of topsoil were placed on top of the landfill and various types of wetlands seeds were planted. Four types of erosion control mat were used to protect plantings and slopes on the landfill and in the wetlands. The entire project was completed in less than 120 days.
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Landfill Bordered Tidal Stream and Sensitive Wetland Area |
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Three Acre Landfill Soil Cap (20,000 yd3 soil cap) |
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¾ Acre Wetlands Excavation (4,600 yd3 of oil contaminated glass placed under cap) |
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¾ Acre Wetland Restoration |
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80 Wetland Plants and Special Wetland Seed Mixture |
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Restoration Areas Four Types of Erosion Control Mat used on Slopes and in Wetlands. |
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