Transcript Agenda - About United Utilities

Tackling Algae
March 2015 update
Agenda
• Background
• Our algae working group
• Raw water management
– Catchment
– Algae management plans
– Reservoir mixing
• Detection & analysis
– Algae monitors
– Sampling programme & rapid detection
• At the WTW - trigger levels and treatment
• Next focus areas
Background
•
Two water quality events in 2014
– Cloughbottom & Denton Water Treatment Works (WTW)
•
Increase in ‘earthy/musty’ taste and odour customer contacts
•
Increase in taste and odour ‘fails’ at the customer’s tap
•
Climate change - WRc report January 2013
– “…Climate change is likely to lead to increased algal growth ….”
– “…Cyanobacteria grow better at higher temperatures … the predicted
warmer world of the late 21st century will be more suitable for these algae”
– “There is also some evidence that climate change could increase nutrient
loading to lakes”
Our algae working group
Prevent - control - detect - treat
Objectives:
•
To reduce ‘unwanted’ customer contacts due to taste and odour
•
To eliminate associated category 3 water quality events
•
To reduce the cost of treatment to remove algal taste and odour compounds
•
To avoid impacts of increased solids loading and prolonged WTW shut down
Our algae strategy:
•
A twin track approach for interventions with prevention/treatment on the
catchment and in reservoirs as well as at the WTW
Prevention & Control
Catchment
Pro-active
interventions to
prevent algal
blooms
Nutrient reduction
Replace septic tanks
Cover manure heaps
Fix leaking mains & sewers
Nutrient & manure planning advice
Prevent stock access to watercourses
Buffer strips
Animal housing
Algae management plans
•
42 Site specific plans in place
•
Actions to be taken on catchment, reservoirs and at the WTW to prevent algae
growth, or to control it when it does occur
•
Reservoir actions include:
– Source selection
– Mixing
– Scour
– Variable depth draw off
– Compensation flows & overflows to increase turnover
•
Roles & responsibilities clarified
Reservoir mixing
Prevents ‘ideal’ conditions for algae growth:
• ‘Resmix’
• Existing bubble barriers
Detection & analysis
Algae monitors
•
Hand held & on-line monitors
– trend monitoring & source selection
– will be used to develop site specific trigger levels
•
Installing on-line monitors high risk sites & Safeguard zones
Detection & analysis
Sampling programme & rapid detection
•
Risk assessment of all sites completed
•
2015 sampling programme agreed
– 25% increase from 2014, based on risk
– Final water analysis where PAC or GAC in use
– Algsys instrument based on fluorometry
•
Raw smell and final taste and smell procedure re-launched in November
and in use at all sites
At the WTW - trigger levels & treatment
•
Currently regional trigger levels
•
Algae trigger levels revised early February
– Introduced blue green algae pigment trigger
•
Rapid notification if trigger levels reached
•
GAC installed at 10 of our WTWs
•
Three additional mobile PAC rigs ordered
– enabling works and delivery plans being developed for at risk sites
– will treat up to 20Ml/d
Our next focus areas
•
Cost and scope the most beneficial innovative solutions to pursue
•
Woodland policy and wildlife management under review
•
Further benchmarking meeting with other water companies & CEH
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Grow our understanding of all factors & complex data
•
Biology
– Benthic vs planktonic
– Actinomycetes etc