BCRUA Deep Water Intake Alternative Site

StudyNovember 15, 2007

Project timeline

• Phase 1 – 30 mgd (summer 2010)– 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:– 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 withRemote 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 withRemote 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