Environmental Engineering Reference
In-Depth Information
5.4 Surface Accidental Releases of Liquids and Chemicals
Shale gas well drilling and hydraulic fracturing requires a period of 1-2
months of intense activity around the well, during which spillages or leakage
of polluting substances may occur. Activities which have been identified as
hazardous include: re-fuelling of diesel tanks, bulk-chemical or fluid trans-
port and storage, equipment cleaning, vehicle maintenance, leaking pipe
work, drilling mud/cement mixing areas, wastewater storage and transport.
As significant volumes of fluid and chemicals are stored/mixed/used on site
there is potential for either direct run-off to drains, ditches and other water
courses, or infiltration to ground which may adversely impact surface water
quality and ecology or may lead to localised groundwater pollution.
In the United States, storage or retention pits are frequently used for
holding freshwater and/or wastewater. These are unlikely to be allowed in
the UK and fluids will be required to be held in storage tanks. Tanks can also
be used in a closed-loop drilling system. Closed-loop drilling allows for the
re-use of drilling fluids and the use of lesser amounts of drilling fluids.
Closed-loop drilling systems have also been used with water-based fluids in
environmentally sensitive environments in combination with air-rotary
drilling techniques. The containment of fluids reduces the risk of leakage
and is likely to represent standard practice if shale gas exploitation goes
ahead in the UK.
6 Risk Assessment, Regulation and Groundwater Protection
There is a well-established oil and gas industry in the UK and more than
2100 wells have been drilled since 1902 for hydrocarbon exploration or ex-
ploitation.
35
It is a regulated industry with several regulatory bodies and
agencies responsible for the different aspects of the operation (see Table 7).
Whilst shale gas is a new development in the UK, many of the regulations
and procedures will be applicable or directly transferable. The key bodies
that will be involved are the Department of Energy and Climate Change
(DECC), the relevant environment agency (Environment Agency, Scottish
Environment Protection Agency, Natural Resources Wales or Northern
Ireland Environment Agency), Healthy and Safety Executive and local (and
mineral) planning authorities. To oversee the safe and responsible devel-
opment of unconventional oil and gas and ensure co-ordination of activities
across the UK, the Government established the Oce of Unconventional Gas
and Oil (OUGO) in 2013. One of the first outputs from OUGO is a roadmap
that provides an introduction to and guidance on the planning and per-
mitting process for unconventional oil and gas exploratory well drilling.
36
OUGO recognises that, as the industry is in its infancy in the UK, the
roadmap will need to be revised as legislation develops, new regulations are
introduced, or when best practice becomes established.
Currently the roadmap does not address the full range of environmental
risks and risk management requirements. For example, it does not cover
