| Penrice have been
occupying their Osborne site for the last 80 years, undertaking
a wide range of activities involved in the processing of soda ash
and sodium bicarbonate.
McMahon Service were engaged to remediate soils
within the area of a former above ground storage tank for fuel oil
and existing underground storage tanks. The bulk of the contamination
resulted from a 500,000 litre fuel oil spill that occurred on the
site in the 1970's. Excavated contaminated material was treated
in a series of purpose built biopiles. These biopiles were made
up of the following:
- Contaminated Soil
- Mulched Green Waste
- Fowl Manure
- N,P,K and Urea Fertilizer
- Water
- Straw
In preparation for the decontamination a series
of leachate and condensate collection lines were installed on top
of an onsite welded HDPE liner. These pipes were reticulated to
a series of manifolds, then further reticulated to a purpose built
carbon filtered air extraction and filtering system. The vacuum
system comprises a 3000 litre pressure vessel acting as a moisture
trap, a 3000 litre capacity carbon filter and a purpose built roots
vacuum blower. The entire vacuum pump system has been installed
on a skid-mounted platform for easy maneuverability on site.
The contaminated soil was mixed on a purpose
made mixing pad and added to the biopile. Once the biopile was constructed
to sufficient capacity a series of water dripper lines were installed,
and the HDPE cover installed and welded in place, providing an air
tight envelope. During the life of the biopiles the piles were monitored
and inspected daily for:
- Temperature
- Moisture
- O²
- CO²
- Vacuum Air Velocity
Particular problems that were successfully overcome
on site included the
following:
- Undertake well point dewatering for excavation of contaminated
material;
- Monitoring of dewatering water to ensure only 'clean' water
was
removed, without effecting the contaminated plume of underground
water;
- Working within the constraints placed on the team by Penrice,
working in
an operational site;
- Design and construct the vacuum system, with no singular
source to call
on for expert information;
- Source materials of the appropriate quality in the required
quantities.
On completion of the bioremediation of the hydrocarbon
impacted soil the remediated soil was used as nutrient rich landscape
material within the site.
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