research project aims to locate non-point sources of pollution which are
adversely affecting the water quality of the Bourne Stream, Bournemouth,
Dorset. As the stream discharges into Bournemouth bay any poor water
quality affects the chances of Bournemouth Beach reaching the guideline
standards of the EC Bathing Water Directive.
This is important to Bournemouth Borough Council as these must be
met to achieve Blue Flag status and increase the profile Bournemouth
have previously been carried out into point source and non-point source
discharges using funding from the Environment Agencies Research and
Development budget. Sustainable
Urban Drainage systems have also been implemented but problems still occur
suggesting that they must arise from a non-point source.
project was based around chemical sampling of the stream water quality,
allowing areas with regular or recurring issues to be identified.
Once these areas had been selected the area around the stream was
examined to find possible causes of the lowered water quality.
quality was tested for eight parameters on four different occasions, after
statistical evaluation of the results three areas with problems were
identified. None of these areas had the same problem during each sampling
session but levels of determinants were high and seemed to reflect
techniques to deal with the problems have been identified based on the
problem parameters and on cost versus benefits basis.
These suggestions range from public education to the use of
sustainable urban drainage techniques.
Thanks to Ian's study, and specific problems recognised at Prince of Wales Road,
partner organisation Wessex Water have managed to identify illegal grey- and black-water misconnections
from new-build properties in the area; subsequently a significant source
of illegal organic pollution of the Bourne stream has now been rectified.
note: a member of Bournemouth
Borough Council's Technical Services Team would like to point out in
response to some of the suggestions in Ian's paper:
mention is made of road grit having chemical properties that affect stream
quality. Grit is washed material from a local Avon Valley gravel supplier
and will be of a siliceous base and also inert. It is mixed with road salt
to add traction once snow has fallen. Road salt is used at different
spreading rates prior to snow fall and it is this that will generate some
chlorine based compounds in the natural water environment when flushed out
of gulley pots by rainfall.
b) mention is made of the Bourne Stream flowing into storm tanks at the
Pier Approach area. The Bourne Stream does not enter any storm tanks at
all, it either enters the combined storm overflow from Bournemouth No.1
Pumping Station in dry weather, or in heavy rainfall, is diverted over a
weir into the short concrete Bourne Stream culvert on the east side of the
Pier. The Wessex Storm Tanks are used to receive consented discharges from
Bournemouth No.1 Pumping Station when there is no capacity in the Coastal
Interceptor Tunnel Sewer that is used to provide storm storage combined
with storm storage at Holdenhurst STW.