Transcript BCRUA Deep Water Intake Alternative Site Study

BCRUA Deep Water Intake
Alternative Site Study
November 15, 2007
Project timeline
• Phase 1 – 30 mgd (summer 2010)
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Floating intake
78-inch raw water pipeline
Regional water treatment plant
Treated water pipelines to Leander, Cedar Park,
Round Rock
• Phase 2 – 70 mgd (2016)
– Deep water intake (may be accelerated depending on
lake levels)
– 84-inch raw water pipeline from intake to Phase 1
pipeline
– Water treatment plant expansion
Phase 1 Intake
• Floating intake will utilize existing “Twin
Creeks” barge
• Barge will be expanded with eight new
pumps
• Expected to operate until deep water
intake is constructed
Phase 1 Intake (cont’d)
Twin Creeks Intake
Cedar Park Intake
View looking west from shoreline
Need for Deep Water Intake
• LCRA manages Lake Travis
• LCRA’s management plan predicts Travis
may drop below elevation 576 in a severe
drought
• An intake below 576 is required to ensure
water is available in such a drought
Need for Deep Water Intake
(cont’d)
• Deep water is only accessible near the
original river channel
• The Volente area offers access to deep
water and is in closest proximity to the
BCRUA, Cedar Park, & Leander/LCRA
plant site
Site Alternatives Study
• To determine which site is the most
suitable for an intake structure
• Seven sites in the Volente area under study
• Four types of intakes under study
Site Alternatives Study (cont’d)
• Selection will be based on multiple
criteria:
– Minimizing cost
– Compliance with regulatory requirements
– Minimizing social impacts
– Minimizing environmental impacts
• Elimination of all impacts is an
unattainable goal
Site Alternatives Study (cont’d)
• Social impacts include:
– Construction impacts (noise, dust,
traffic disruption, etc.)
– Aesthetics (visibility, architecture,
lighting, noise, traffic, etc.)
– Recreation impacts (restricted area,
navigation hazards, etc.)
Site Alternatives Study (cont’d)
• Environmental impacts include:
– Construction impacts (noise, dust, etc.)
– Geologic impacts (groundwater, karst)
– Habitat impacts (endangered species,
particularly birds and karst
invertebrates)
– Water quality
Alternative Sites
Alternative Intakes
• Four types of intakes to be evaluated at each site:
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Microtunnelled lake tap
Microtunnelled lake tap with remote pump station
Tower
Inclined pump
Microtunnelled Lake Tap
Microtunnelled Lake Tap (cont’d)
• Advantages:
– No structure in lake
– Maximum opportunity for
aesthetic/architectural compatability with
surroundings
• Disadvantages:
– Second most expensive to construct
– Cannot be located in flood plain
– Must be within 1,200 feet of deep water
Microtunnelled Lake Tap with
Remote Pump Station
• Similar to Microtunnelled Lake Tap, but a
smaller gate shaft near the lake feeds
water through a deep tunnel to a pump
station further away from the lake
• A smaller building is located at the lake
• The larger pump station is located
elsewhere
Microtunnelled Lake Tap with
Remote Pump Station (cont’d)
• Advantages:
– No structure in lake
– Maximum opportunity for aesthetic/architectural
compatability with surroundings
– Gate shaft might be in flood plain with suitable
design
• Disadvantages:
– Most expensive to construct
– Gate shaft must be within 1,200 feet of deep
water
Tower Intake
Tower Intake (cont’d)
• Advantages:
– Moderate construction cost
– Can be constructed in flood plain
• Disadvantages:
– Large structure in lake
– Increased visibility
Inclined Pump Intake
Inclined Pump Intake (cont’d)
• Advantages:
– Lowest construction cost
– Pump station can be constructed in flood
plain
• Disadvantages:
– Inclined pumps have increased maintenance
problems, and 2,000 HP installations are
unproven
– Pump barrels are exposed on lake shore
Site Selection Process
• Study Initiation
– Public meeting to solicit comments and future participation
• Technical/Feasibility Review - Evaluate 28 alternatives for
feasibility, cost, pipeline routing (approx 2 months)
– Working meeting to discuss findings and review selection
criteria and weighting factors
• Environmental/Social Impacts Review - Evaluate selection
criteria (approx 2 months)
– Working meeting to present preliminary selection and solicit
input
• Finalize Selection - Evaluate comments and update
selection matrix (approx 1 month)
– Working meeting to present final selection
Questions & Comments
 Please
- Provide comments regarding:
• Selection criteria
• Alternative sites, any other potential sites
within the study area
• Intake alternatives
- Hold all questions relating to water rights,
alternative sources, and participation in
the City of Austin’s project