City of Waukesha West-Side and Southeast Interceptor Sewer Cost - - PowerPoint PPT Presentation

City of Waukesha

West-Side and Southeast Interceptor Sewer Cost Comparison Analysis

Central States Water Environment Association, May 2012

Agenda

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▼ Purpose ▼ Basis of Analysis ▼ Evaluation of Existing Collection System

– System Flow Evaluation – Pump Station Considerations

▼ West-Side

– System Evaluation and Recommendations

▼ Southeast Side

– System Evaluation and Recommendations

▼ Implementation Schedule

Waukesha, Wisconsin

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Purpose

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▼ Waukesha currently has 42 pump stations ▼ The Sanitary Sewer Master Plan analyzed the potential

for the installation of two (2) sanitary interceptor sewers, with the potential to remove 15 pump stations

▼ The Purpose is to determine the most cost-effective

solution for conveyance of wastewater flows to the Wastewater Treatment Plant (WWTP) which provides an acceptable level of service for the City of Waukesha and its residents/businesses

Basis of Analysis

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▼ Design Flow / Level of Service Determination

– June 2009 Event with Future Flows Added

▼ Life Cycle Cost Analysis

– 20, 50 and 60 year periods analyzed

▼ Pump Station / Force Main Considerations

– 60 Year Structural Life, 20 Year Pump Replacement Cycle with Maintenance Considered.

▼ Interest Rate – 4.6% (per City Rate Consultant) ▼ Risk / Construction Considerations

Design Flow Determination

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▼ June 2009 Event is considered to be a 25-year event ▼ Selected as it stressed the collection system, resulting in

surcharging, but to acceptable levels which did not result in basement backups or bypassing.

▼ Additional future flows were added for:

– Development (including a portion of the Village of Wales) – Mound or Septic System Abandonment – Future I/I increase was not considered as the City will maintain their collection system through standard practices (replacement, lining, etc.)

▼ Wisconsin DNR has not determined a required level of service for

Sanitary Sewer Collection Systems, but a 25-year period is reasonable.

Life Cycle Cost Analysis

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▼ 20-, 50- and 60-year periods were mutually accepted. ▼ Differing flow volumes for each period were not considered.

Development and all future flows were assumed to occur within the initial 20-year period.

▼ A Present-Worth Analysis Period was selected, which included

salvage values at the end of each evaluation period.

▼ Capital costs for construction, maintenance, utility, rehabilitation

and replacement costs were considered for both the interceptor and pump station alternatives.

▼ Any analysis within 10% of each other was considered to be an

approximately equal scenario.

Interceptor Sewer Cost Analysis

▼ Developed tables of unit prices for open cut and

trenchless construction, dependent upon depth of excavation

▼ The depth of excavation is not as pertinent to the

horizontal construction of the sewer, but more for the size and depth of the access shafts for the sewer construction.

▼ Restoration was not considered a key factor in route

determination, rather location of pump stations and depth

• f excavation determined proposed interceptor sewer

alignments.

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Pump Station / Force Main Considerations

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▼ 60-year structural life (building, wet well, valve vault, etc.) ▼ Pumps, controls, electrical, HVAC and other equipment will be

replaced on a 20-year cycle.

▼ Pumps will be rebuilt on a 7-year cycle within the 20-year

replacement timeframe.

▼ Waukesha has an annual parts budget of approximately $2,000 per

pump station.

▼ All force mains will have a useful service life equal to that of the

pump station structural elements (60 years). All existing ferrous force mains will be replaced with the first pump station replacement,

• r sooner, depending upon their current condition.

Pump Station / Force Main Cost Analysis

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Risk / Construction Considerations

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▼ Grade vs. Pipe Slope ▼ Open Cut vs. Trenchless Construction ▼ Groundwater and Subsurface Soil Conditions ▼ Wetlands and Open Waterways ▼ Areas of Historical Significance ▼ Proposed Easements / Property Acquisitions ▼ Pavement Condition Analysis ▼ Risk of Failure

West-Side of Waukesha Existing Collection System

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▼ Required Improvements:

– Pebble Valley Pump Station capacity increase from 3.3 MGD to 6.4 MGD. – 8-inch sanitary sewer on Pebble Valley Road must be increased to 15-inch for 1,700 LF to Pebble Valley Pump Station. – 10-inch sanitary sewer from Manhole 4456 to the Summit Pump Station must be increased to 12-inch for 1,024 LF. – From the discharge of the Summit Pump Station Force Main to North Comanche Lane must be increased from a 15-inch to an 18-inch for 2,805 LF. – From North Comanche Lane to Madison Street must be increased from an 18-inch to a 21-inch sanitary sewer.

▼ Collection System Weir:

– Alternate 1A – All flows which exceed the capacity of Greenmeadow PS are directed to Coneview PS. – Alternate 1B – All excessive flows are routed to Greenmeadow PS.

West-Side of Waukesha Existing Collection System

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West-Side of Waukesha Proposed Interceptor Sewer

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West-Side Interceptor Sewer Cost Comparison Analysis

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Southeast Side of Waukesha Milky Way Road PS Abandonment

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West-Side of Waukesha Recommendations

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▼ Greenmeadow – Woodfield to WWTP Interceptor Sewer ▼ Upgrade Pebble Valley and Coneview Pump Stations ▼ Maintain the following Pump Stations:

– Tallgrass – Summit – Madison Street – Fiddler’s Creek – MacArthur Road – Badger Drive

Southeast Side of Waukesha Existing Collection System

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▼ Required Improvements:

– The existing 15-inch sanitary sewer must be increased to a 36-inch for the crossing

• f West Avenue to the influent of the West Avenue Pump Station.

– The West Avenue Pump Station must be increased from 1.7 to 8 MGD.

▼

There are required gravity sewer improvements along Progress Avenue, Prairie Road, Sentry Drive due to the significant capacity increase at West Avenue Pump Station.

Southeast Side of Waukesha Existing Collection System

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Southeast Side of Waukesha Proposed Interceptor Sewer

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▼

Route flows to Fox Point PS or directly to WWTP.

▼

Alternate 2A – Route flow from Heyer Drive PS and Milky Way Road PS to WWTP directly along Sunset Drive

▼

Alternate 2B – Route flow from Heyer Drive PS and Milky Way Road PS to Fox Point PS where flows would be pumped to WWTP

Southeast Side of Waukesha Proposed Interceptor Sewer

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Southeast Side of Waukesha Recommendations

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▼

Southeast Interceptor from West Avenue PS to Fox Point PS

▼

Upgrade Fox Point PS (3.1 to 9.6 MGD) including new 16” FM to the intersection of Sunset Drive and Sentry Drive

▼

Decommission Sunset Drive PS and extend a gravity sewer to the new Fox Point PS.

▼

Decommission Milky Way Road PS and extend a gravity sewer to Heyer Drive PS

▼

Maintain the following Pump Stations: – Heyer Drive

City of Waukesha Sanitary Collection System Implementation Schedule

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Year Description 2012 Summit Ave PS Upgrade 2012 Bluemound Rd PS and FM upgrade 2012 Hollidale PS and FM upgrade 2012 River Place PS Upgrade 2012 Fox Point PS Upgrade (controls only) 2013 MacArthur Rd PS and FM upgrade 2014 Walmart PS and FM upgrade 2015 Badger Dr PS and FM upgrade 2015 Greenmeadow Interceptor Sewer Design 2016 Fox Point PS Upgrade - Design 2016 Southeast Interceptor (West Avenue to Fox Point) - Design 2016 Milky Way Sewer - Design 2016 Patricia Ln PS upgrade 2016 Greenmeadow Interceptor Sewer Construction 2017 Pebble Valley PS and FM upgrade 2017 Southeast Interceptor (West Avenue to Fox Point) - Construction 2018 Pebble Valley PS and FM upgrade 2018 Milky Way Sewer - Construction 2019 Ruben Dr FM upgrade 2020 Coneview Dr FM upgrade 2021 Springbrook Dr FM upgrade 2022 Summit Ave FM upgrade 2023 Heyer Dr FM upgrade