Assessment & Monitoring
An essential aspect of avoiding or minimising the various problems outlined above, is the use of appropriate and effective
techniques to assess what may happen and monitor what does happen. These will be looked at in turn.
Assessment
It is highly likely that an assessment will take place as part of an EIA, leading to the submission of an
Environmental Statement as part of an application. A detailed summary of the various assessment techniques used is given in the
original Guide to Good Practice78. A typical sequence of events may include the items given in Table 10.
|
| Water Impact Assessment |
| Initial desk studies and site
inspections. |
Ground investigations:
- geological mapping;
- drilling;
- trial pits;
- test pumping;
- geophysics.
|
| Baseline monitoring. |
| Assessment of hydrogeology and
water balance. |
| Assessment of potential impacts. |
| Propose appropriate mitigation. |
| Reporting. |
| Regular review. |
Monitoring
More attention will now be given to the various monitoring techniques, as these will enable a measure of the effectiveness of
good practice to be made, and highlight areas which may need further attention.
Any requirement for monitoring must be agreed by the MPA and the operator, in consultation with the Environment Agency. It is
likely to include aspects of water quality and water levels (Table 12) over the three phases of a site given in Table 11:
|
| Monitoring the water
environment |
| Pre-operational or
baseline monitoring |
This should cover the
widest area and include the largest number of parameters. This should
be done for as long as possible, preferably a minimum of 1 year, and ideally
3 to 5 years. Some data can be collected easily on daily or weekly basis,
but other information may need to be sampled less frequently. |
| Operational monitoring |
The main purpose here is to assess
whether the changes brought about by the site are having an adverse effect
on the water environment. Thresholds for implementing mitigation measures
should be set and checked for regularly. |
| Post-operational and reclamation
monitoring |
Monitoring should could continue
after operations, particularly where de-watering has taken place and the
groundwater is rising again. |
|
| What to monitor |
| Groundwater levels |
Monitor in observation
boreholes and existing wells. Can be measured with hand-held dip meter,
or monitored automatically. |
| Groundwater quality |
Monitor in observation boreholes
and existing wells. Samples can be taken from the same boreholes as used
for monitoring level. The water in the borehole MUST be purged to remove
"stale" water A number of pumping methods are available. Chemical analysis
should be carried out in an approved laboratory. |
| Surface water quality |
Water and stream bed quality and
biodiversity. Samples should be taken upstream, downstream and at the
point of discharge, and should be collected following appropriate procedures.
The key factor here is that the discharges meet the consent levels set
by the MPA. |
| Surface water flow rates |
Flow rates can be measured using
a flume or other engineered gauging device, preferably with automatic
monitoring. Often flow rates are measured by monitoring the surface water
level, and converting this to a flow rate by knowing the cross-sectional
area of the channel. This is sufficient where the level is monitored at
a man made section (e.g. square section or v-notch weir), but is less
accurate in natural sections. |
| Surface water levels in lakes and
ponds |
A permanently installed graduated
staff will allow manual readings, or a float device connected to a logging
unit can be used for automatic readings. |
| Weather conditions |
To enable any changes to be related
to climatic conditions, as well as to the impact of quarrying. |
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Computer Modelling
Modelling for both surface water flows and groundwater is becoming increasingly common. They can be used for simple tasks,
such as improving the understanding of the basic mechanisms of a system, to more complex situations of testing and predicting
the effects of a range of options.
HOWEVER, it is vitally important to recognise that models are only simplified approximations of reality, and are only as good
as the data fed into them. The conclusions from modelling should always be verified by independent specialists.
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