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2.1.1 Narrative
Surface
soil (0-1’ bg) contains lead above 350 ppm, the level of concern, in five of the seven designated playground
areas within the housing complex, the public raised garden bed area, and one
private garden. The average
concentration of lead in the five play areas is 635 ppm. In
most cases, this removal action will be limited to removing the top foot of
contaminated soil and replacing it with clean fill in the playgrounds as well
as the identified gardens. In 2 of the
playground grids, the play areas will be raised in a manner similar to the raised
garden beds.
On October 1,
2015, EPA’s cleanup contractor began mobilizing equipment to the site and site
prep activities continued into the following week.
Please refer to
the map located in the documents section of the website www.epaosc.org/MedfordHousingAuthority for the locations
of the specific grids.
Excavation of a playground in grid 19 began soon after site prep,
followed by grid 14, where the community raised bed gardens were located. In this location, the soil underneath the
raised beds was removed and will be replaced with clean fill. The raised beds will be filled with clean
loam as well.
On October 14 and 15, a tree service was subcontracted to remove a
total of 14 trees from 4 different grids.
These trees were growing in contaminated soil and the choice of which
trees to remove was made in conjunction with representatives of the MHA. Some of the remaining stumps were excavated
from grid 14 on October 28 and from grids 6 and 7 on November 5.
Grids 6 and 7 have been combined into 1 area that is being raised due
to the topography as opposed to excavation and backfill. Backfilling of this area with a gravel base began
on November 9.
On October 16, samples were collected from the loam pile at
a local subcontracted gravel pit. Due to
miscommunication with the laboratory, the 2 samples were inadvertently
composited and only 1 sample was analyzed. Results indicated that the sample
was slightly above the Massachusetts standard for residential surface soil for
one compound, benzo(a)pyrene. Unfortunately,
a number of loads had already been delivered to the site and a small amount had
been spread out in one location. A
second sample was collected from the loam pile on November 3 to determine if an
average of the 2 concentrations was below the standard. The second sample proved to be almost as high
for that particular compound, so it was decided that the material could not be
used for this application. The stockpile
was removed from the site on November 12 and trucked back to the gravel
pit. The portion that was spread out was
removed on November 16.
While 14 trees were removed to allow for excavation in particular
locations, 4 trees within the hot zones were kept, due to the shade and
ambiance they provide. An attempt made
to save them by carefully removing the soil from around its roots.
Hydro-excavation was chosen as it appeared that it would be the gentlest method
of soil removal that would give the tree the largest chance of long-term
survival. This proved erroneous however
as the high pressure water spray began stripping the bark off of the roots. An
arborist, subcontracted by EPA’s START contractor for his technical expertise
during this removal, stated that this would eventually lead to the undermining
and eventual death of the tree.
Hydro-excavation was soon halted and working with the arborist, it was
decided that a minimal covering of the roots with a loamy sand would provide
sufficient cover and would allow the trees to survive.
Air monitoring is being
conducted in all locations where intrusive activities involving contaminated
soil are occurring. This is to ensure
that contaminated soil/dust is not being generated and/or released during
removal activities.
None of the playground
equipment located in the 4 grids could be salvaged as it had been in place for
many years. The equipment had deep and
expansive footings, was rusted to a point where they could not be dismantled
and moved, and was no longer to the present code required for commercial
playgrounds. Therefore, the equipment
will eventually be replaced.
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