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Case Study of PRB Application for the Remediation of Groundwater
• Ethylene dichloride
(EDC, also known as 1,2-dichloroethane or
1,2-DCA), 1966–2001, which included production of vinyl chloride
monomer (VCM) and polyvinyl chloride (PVC) up to 1997
In the early years of operations at BIP, statutory controls for effluent management, treatment, and disposal were minimal. Indeed, up until 1958, no
trade wastewater discharges were connected to sewers, and trade waste
was discharged directly to a man-made unlined stormwater drain known
as Springvale Drain, which flows to Botany Bay, or to on-site soak-away
ponds. The equipment was likely to have been drained and decontaminated
onto the plant floor, with the waste draining into effluent pits and drains
that had some degree of leakage. As the site is underlain by sandy soil, liquids quickly drain away. Waste products from the CHC plants were typically stored in steel drums pending treatment or disposal—often for long
periods in open unpaved areas. In some areas, the drums corroded and
leaked their contents into the ground. As a result, extensive soil contamination occurred, which eventually led to contamination of the groundwater
beneath the site.
The BIP is located approximately 10 km south of downtown Sydney and
about 1.5 km hydraulically upgradient (northeast) of Botany Bay, at the
southern end of the Botany Sands Aquifer—a high-yielding groundwater
resource. (An abundant source of high-quality groundwater was one of
the reasons the location was chosen to establish the site in the 1940s.) The
Botany Sands Aquifer stretches in the form of an arc from Bondi Beach
in the east, through Centennial Park and Moore Park in the north, St
Peters and Tempe in the northwest, around the western side of Botany Bay
through Brighton-Le-Sands and Ramsgate, and encompassing the Kurnell
peninsula in the south.
Groundwater quality in the vicinity of BIP is affected by natural organic
compounds and sulfides, and low pH. The natural contaminants are largely
artifacts of the coastal swamps and dunes that characterized the area for
the last 10–15,000 years. The aquifer lithology consists of fill, Aeolian sands
intercalated with discontiguous peat layers, overlying a generally competent
clayey sand layer immediately above the sandstone bedrock (WoodwardClyde, 1996). Around the BIP, the aquifer thickness is typically 20–40 m
and the depth to the groundwater is generally 4–6 m below ground surface
(bgs), progressively reducing on Southlands and toward Botany Bay (Figure
12.1). Hydraulic conductivity of the aquifer is high, generally 10–40 m/day.
Regional groundwater flow is southwesterly toward Botany Bay.
A number of environmental investigations and regular monitoring events
have been conducted on and around the BIP since 1989. Several groundwater plumes have been identified originating from up to nine inferred source
areas. These are shown in Figure 12.1, together with some key infrastructure,
groundwater flow direction, and an indication of the overall 1 mg/L CHC
plume envelope.
Case Study of PRB Application for the Remediation of Groundwater
• Ethylene dichloride
(EDC, also known as 1,2-dichloroethane or
1,2-DCA), 1966–2001, which included production of vinyl chloride
monomer (VCM) and polyvinyl chloride (PVC) up to 1997
In the early years of operations at BIP, statutory controls for effluent management, treatment, and disposal were minimal. Indeed, up until 1958, no
trade wastewater discharges were connected to sewers, and trade waste
was discharged directly to a man-made unlined stormwater drain known
as Springvale Drain, which flows to Botany Bay, or to on-site soak-away
ponds. The equipment was likely to have been drained and decontaminated
onto the plant floor, with the waste draining into effluent pits and drains
that had some degree of leakage. As the site is underlain by sandy soil, liquids quickly drain away. Waste products from the CHC plants were typically stored in steel drums pending treatment or disposal—often for long
periods in open unpaved areas. In some areas, the drums corroded and
leaked their contents into the ground. As a result, extensive soil contamination occurred, which eventually led to contamination of the groundwater
beneath the site.
The BIP is located approximately 10 km south of downtown Sydney and
about 1.5 km hydraulically upgradient (northeast) of Botany Bay, at the
southern end of the Botany Sands Aquifer—a high-yielding groundwater
resource. (An abundant source of high-quality groundwater was one of
the reasons the location was chosen to establish the site in the 1940s.) The
Botany Sands Aquifer stretches in the form of an arc from Bondi Beach
in the east, through Centennial Park and Moore Park in the north, St
Peters and Tempe in the northwest, around the western side of Botany Bay
through Brighton-Le-Sands and Ramsgate, and encompassing the Kurnell
peninsula in the south.
Groundwater quality in the vicinity of BIP is affected by natural organic
compounds and sulfides, and low pH. The natural contaminants are largely
artifacts of the coastal swamps and dunes that characterized the area for
the last 10–15,000 years. The aquifer lithology consists of fill, Aeolian sands
intercalated with discontiguous peat layers, overlying a generally competent
clayey sand layer immediately above the sandstone bedrock (WoodwardClyde, 1996). Around the BIP, the aquifer thickness is typically 20–40 m
and the depth to the groundwater is generally 4–6 m below ground surface
(bgs), progressively reducing on Southlands and toward Botany Bay (Figure
12.1). Hydraulic conductivity of the aquifer is high, generally 10–40 m/day.
Regional groundwater flow is southwesterly toward Botany Bay.
A number of environmental investigations and regular monitoring events
have been conducted on and around the BIP since 1989. Several groundwater plumes have been identified originating from up to nine inferred source
areas. These are shown in Figure 12.1, together with some key infrastructure,
groundwater flow direction, and an indication of the overall 1 mg/L CHC
plume envelope.