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
3.4.8 DWI recommended that NI
Water reviewed its operational
procedures regarding tankering into
service reservoirs including operational
monitoring.
NI Water follows good
operational practice during
filling operations. Routine
compliance monitoring
was carried out. Suggest
we discuss with DWLG
and incorporate into
Guidance Document for
Water and Health
Professionals.
DWI’s opinion is that
routine compliance
samples are not sufficient
when there is significant
operational work ongoing.
A comprehensive
programme of water
quality checks through a
robust operational
sampling programme is
required.
NI Water to outline its
proposals regarding
mitigation of the risk of
tankering into service
reservoirs at the next meeting
of the DWLG in June 2011.
Action status: Ongoing
3.4.9 DWI required an assurance
regarding the restoration of supplies
and the potential impact on water
quality.
NI Water carry out
continual risk
assessments on the
possible impacts of
networks operations on
water quality.
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.
NI Water to outline its
proposals regarding the risk
assessment process
at the next meeting of the
DWLG in June 2011.
Action status: ongoing
4 of 10