Our Ref: DWI/2/10 Event 30/10 Date: 9 June ... - Derry City Council

Annex 2
DWI FINAL ASSESSMENT SUMMARY - ADVERSE WEATHER INCIDENT AFFECTING SUPPLIES ACROSS NORTHERN
IRELAND, 27 DECEMBER 2010 – 6 JANUARY 2011
DWI Requirement/ Recommendation
in Initial Assessment Letter of
4 March 2011
Summary of NI Water
Response received
1 April 2011
DWI Assessment of
NI Water Response
Further Action Required
Distribution Networks / Systems
Recovery
3.4.5 DWI requires an assurance that
the risk of supplying water to
customers during the incident was
considered, and recommended that
operational procedures were reviewed
in liaison with Public Health Agency
(PHA) and the Inspectorate.
Assurance given
regarding risk
assessments and
refers to mitigation
measures. To be raised at
the next meeting of the
interagency Drinking
Water Liaison Group
(DWLG).
NI Water did not provide
sufficient detail as to how
the assessment of risk
was fully considered.
Reliance on compliance
samples and the limited
operational samples taken
during the period of the
incident was in DWIs
assessment insufficient to
enable a full evaluation of
the risks to be considered.
These were not normal
operating conditions and
for example sampling
downstream following
repair several days later
(or not at all) would not
fully inform the risk of
potentially contaminated
water being present for
consumers.
NI Water to outline its
procedures on its assessment
of the risk of supplying
unwholesome water during an
incident taking account of its
assessment of how this could
constitute a danger to public
health. This update to be
provided at the next meeting
of the DWLG in June 2011.
Action status: Ongoing
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