Lemon Lane Final Report
June, 2001
1.0 Introduction | 2.0 Site Description and History | 3.0 Remediation Planning | 4.0 Changes to Original Work Plan | 5.0 Sampling Activities | 6.0 Preparation of Iterim Cap Surface | 7.0 Intallation of the Geosynthetic Clay Barrier | 8.0 Placement of Geomembrane and Geonet | 9.0 Placement of Vegetative Support Zone | 10.0 Site Surface Water Controls | 11.0 Site Restoration | 12.0 Data Validation | Photos
11.0 SITE RESTORATION
11.1 Soil Preparation and Seeding
The thickness of clean topsoil over the site typically ranged between 10 to 12 inches.
Preparation of the topsoil surface for seeding consisted of back dragging the surface
with the dozer or blading with a motor grader. The topsoil provides a clean cover
over areas outside the cap to support meeting any of the cleanup requirements in
these areas. Placement of the topsoil layer on the cap surface and over adjacent
areas outside the perimeter channels occurred in late November through early
December. This time frame was well beyond the typical fall planting period for
Indiana. Once it became obvious that the schedule for planting would be this late,
winter cover options were investigated. Contact was made with commercial
landscapers, a local government park maintenance district and a hydromulch
equipment vendor to determine the best winter cover composition and method for
application. Through these discussions, it was determined that a thick layer of
hydromulch mixed with seed and fertilizer would provide a stable cover for the
winter. With the seed and fertilizer included, this approach would provide the
opportunity for grass to start growing at the earliest possible time in the spring. This
technique is used by golf course and road projects to winter soil surfaces.
A seed mixture of 80% fescue and 20% rye was used with a fertilizer mix of
18-24-12. The application rate per acre was as follows:
- 3000 pounds of mulch
- 300 pounds of seed
- 200 pounds of fertilizer
- 60 pounds of tackifier
- 40 pounds of polymer
The mulch was composed of 100% wood fiber. The tackifier provided a bonding
agent to hold the wood fibers together. The polymer works in conjunction with the
tackifier to improve bonding of the tackifier. The polymer also helps to hold moisture
to promote seed growth by releasing the moisture as needed. The polymer will also
continue to reabsorb and release moisture for several years further supporting
vegetation.
Two hydromulch machines (600 gallon and 1000 gallon units) were used to spray on
the application of this mixture. Typically three passes over an area achieved the
specified application rate. Water used in the mixture was obtained from the fire
hydrant located at the northeast corner of the site. The mixture was applied to the
cap surface and all disturbed surfaces within the old fence line that were not covered
with riprap. Application of the hydromulch was completed on December 3, 2000.
11.2 Erosion Control
The hydormulch mixture was used to provide a majority of the erosion control. On
the steeper slopes erosion control mat was used in conjunction with the mulch to
insure the maximum erosion control was in place. The mat was a biodegradable
material that will maintain control characteristics for 12 to 18 months.
In addition to the erosion control mat, silt fence was also installed at various
locations where slope erosion could potentially impact the perimeter channel or
where slopes tended to be long. Along the perimeter channel silt fence was installed
on the inside and outside perimeter where the slopes were steep and drained toward
the channel. On the cap surface silt fence was placed along the 882 ft. contour line
This is the approximate location where the slopes of the landfill cap begin to
increase as shown in Figure 8. All silt fencing was installed by placing the bottom
edge in a shallow trench to anchor this edge to the soil surface.
11.3 Borrow Area Restoration
During the remediation and construction of the cap, soil for backfill and grading was
obtained from the borrow area located just to the west of the landfill site. The
surface was initially scraped to remove the topsoil which was stockpiled in the
borrow area. Once excavation of the borrow soil was completed, all slopes created
during the removal were graded to be approximately 3:1. Any large stones
encountered during the excavation of borrow material were buried in the deep
portions of the borrow area. Grading was done with the existing material to provide
drainage and eliminate ponding. The final surface of the borrow area was contoured
to re-establish the original drainage locations and directions. Topsoil was taken from
the stockpile and spread over the surface of the borrow area. The topsoil was
covered with hydromulch using the same procedure and mixture as previously
described for the cap surface. Silt fencing was installed to the southwest of
Sargent's Pond to limit the potential of sediment being carried into the pond from the
borrow area.
11.4 Completion of Piezometers at Surface of Soil Cover
Weather became a factor toward the end of the construction activities in December
at the LL site. The weather prohibited the completion of the surface details for the
six new piezometers. The concrete pad around the riser pipe and the locking cap
assembly will be installed in the spring of 2001.
11.5 Natural Gas Line Installation
Paralleling the old fence along the south and a portion of the east was a natural gas
pipeline buried some three to five feet deep. The gas company abandoned the
portion of the pipe that was within the old fence line of the landfill. During the
excavation to remove the PCB contaminated materials, the abandoned pipe was
removed.
After the area was verified clean and backfilled with clean soil the gas company
installation contractor returned to replace and re-connect the gas line. The new
location follows closely the location of the original line. The location of the new gas
line was surveyed and this information is presented on Figure 8. The new fence line
will be located so that access to the gas line for future maintenance is outside the
fence.
11.6 Cross Section of the Completed Site
The final as-built configuration of the landfill is shown in cross-section in Figure 11.
This figure shows the approximate original ground surface north to south, the
approximate thickness of the consolidated waste materials, and the individual
components of the cap. This figure also shows the general as-built slope profiles,
constructed surface drains and other features, but does not show the bottom of the
waste excavation. The bottom of waste at all locations outside the LOO was a visual
determination that was subsequently verified by post-excavation sampling and
analysis.
11.7 Permanent Survey Benchmarks
Permanent survey benchmarks were established as survey control points by SNA at
locations outside the cap at the LL Site. A table on Figure 9 provides the northing,
Casting and elevation for each control point. These benchmarks may be used to
establish coordinate and elevation control for the purpose of future cap monitoring
work that may be performed.
1 1.8 Demobilization
A preliminary site walk through with WRS, Viacom, PSARA and the government
parties was conducted on November 14, 2000. Three issues were raised. These
included placing erosion control along the railroad embankment in the southwest,
cleaning the road surface on Gray Street and installation of the fence along the
railroad track. At the time the hydromulch was placed erosion control mat was
installed on the railroad embankment. Cleaning of Gray Street was increased to
minimize the soil that collected on the surface from the truck traffic coming of the
cap. The security fence was to be installed when weather permitted. The proposed
layout of the fence is shown in Figure 8 with maintenance equipment access through
gates located on the east and northwest of the cap perimeter.
The final site walk through was conducted on December 6, 2000, with the same
group of people as the preliminary walk through. No issues were raised by any of
the members of the government parties. The condition of the site met with their
collective approval.
Demobilization of the last of the trailers and equipment occurred during the
week of December 10, 2000. The last subcontractor, PSARA, left the site on
December 15, 2000.
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