Cost Estimate Methodology
MEMORANDUM
Updated Project Cost Estimates for CIP
TO:COPIES:
David StangelCathy HoodShannon WilburDavid ParkinsonOctober 4, 1999Cathy Hood 11/1/99Kim Ervin 8/23/00
FROM:DATE:UPDATED:
Purpose
This memo summarizes proposed unit costs and methods for estimating capital
improvements identified in the Sammamish Plateau Water and Sewer District Water
Comprehensive Plan. Construction costs are presented below, generally as unit costs, andare given in August 1999 dollars (Seattle ENR CCI 6928). These costs have been developedfrom CH2M HILL experience, using information from projects in the area when possible.
Contingency, Sales Tax, Engineering, and Administrative Costs
Project costs will be estimated by multiplying construction costs by 1.8, a factor whichallows for 30 percent construction contingency and mitigation expenses, 8.6 percent salestax, and 31 percent for permit applications, engineering, and financial/administrative costs.Right-of way acquisition costs are not included.
Final costs of the projects will depend on actual labor and material costs, actual site
conditions, final project scope, final project schedule, and other variables. As a result, finalproject costs may vary from the estimates presented herein. Because of these factors,funding needs must be carefully reviewed before making specific financial decisions orestablishing final budgets.
Pipelines
The following project costs include:
Ductile iron pipe with push-on joints suitable for 150 psi service
Trench excavation and backfill for 4 feet cover (native BF in unimproved areas,
imported BF in improved areas), thrust blocks, and dewatering for water table 6 feetbelow ground level
Buried valves (at 1000 feet intervals for 16-inch and smaller pipelines and 2000 feetintervals for 20-inch and larger pipelines
Waterless hydrants at 1000 foot intervals on 12-inch and smaller pipelines
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UPDATED PROJECT COST ESTIMATES FOR CIP
Air valves and blowoffs each at 2000 foot intervals on 16-inch and larger pipelinesSurface restoration of 4-inch AC, 12 feet wide for trenches under or crossing streetsfor improved areas, and hydroseeding over native topsoil replacement forunimproved areas. Full width overlays are not included. Traffic control inimproved areas is included.No service connections
Sumps and pumps which are considered adequate for trench dewateringMinimal cathodic protection as required
Unimproved Area Cost per Foot 56657587120166198284365
Improved Street Area Cost per Foot108120134150191236275374467
Diameter 6 8 10 12 16 20 24 30 36
Backup for development of the above costs is included in the attached worksheets.Bored/jacked crossings estimated separately at 3 times unit cost above.Microtunneled crossings estimated separately at 8 times unit cost above.
Pump Stations
No costs have been estimated for rehabilitation/expansion of existing booster pumpstations.
Where (if) additional pumping capacity is needed, it is assumed to be provided by a newbooster pump station. Pump station construction costs will be based on the followingassumptions:
Pressure boost of 75 psi
Above-ground structure, concrete block with wood frame roofMinimum three pumps, including one as standbyNo standby power (emergency generator)
Estimated project costs will be as follows:
Capacity 1 MGD 2 MGD
Cost ($1000)675845
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UPDATED PROJECT COST ESTIMATES FOR CIP
3 MGD 5 MGD 8 MGD 10 MGD1015126015751800
These figures are based on the Standardized Costs for Water Supply Distribution Systems,
prepared for the Environmental Protection Agency, January 1992. For pump stations sizeddifferent from those listed above, the costs were plotted against the pump station capacity todevelop the following linear relationship: Capital Cost = (121830 x Capacity in MGD) +606154.
Reservoirs
Reservoir project costs will be estimated at $0.53/gallon for reservoirs 1 to 3 MG, and$0.43/gallon for reservoirs larger than 3 MG. Standpipe project costs are estimated at
$0.72/gallon. The initial buy-in cost for the Union Hill tank was estimated at $375,000. Thecosts are based on the following:
On-grade steel tanks. Reservoirs larger than 3 MG may be more cost-effectivelyconstructed of prestressed concrete.
Moderate level of site preparation and yard piping, no rock excavation or extensiveearthwork required, moderate surfacing and planting.
Nominal length (200± feet) of connecting pipeline and overflow pipelineSitework cost of $0.32/gallon
Reservoir costs are based on CH2M HILL’s previous project experience and estimates fromMarshall Valuation Service, published by Marshall and Swift.
Reservoir repainting costs will be estimated on the basis of $3.25/SF for interior surfaces (2-3 coats polyamid) and $3.00/SF for exterior surfaces (2-3 coats polyurethane). Costs arebased on sandblast to white metal, with no lead-based paint to remove; lead-based paintremoval will increase costs by a factor of three. For reservoirs of typical heights (32-40 feet),repainting costs for interior plus exterior total:
1-MG2-MG3-MG4-MG5-MG$ 90,000$145,000$185,000$230,000$275,000
Paint in relatively good condition requiring only spot blasting and touch-up prior torecoating is estimated to cost $2.00/SF and repainting costs will be reduced from thosetabulated above.
Note that repainting costs are for standard painting schemes. Painted graphics/scenes on areservoir would increase the repainting costs.
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UPDATED PROJECT COST ESTIMATES FOR CIP
Wells
Estimated project well cost of $414,000 each is based on the following:
1,000 feet deep.
500 feet of 24-inch diameter upper casing; 500 feet of 20-inch diameter lower casingto accommodate 2,500-gpm pump.
Estimated project pump cost of $180,000 each is based on the following:
300 foot pump setting.400 HP, 2,500 gpm.
Estimated project pump station (well building) cost of $540,000 each is based on thefollowing:
Concrete block building, wood frame roof.
Power available within 300 feet; transformer by power company.Nominal site improvements, fence, grading, surfacing.Nominal (100±feet) connecting pipeline.No standby power (engine generator set).
Well costs are based on CH2M HILL experience with 8-10 test and production wellsconstructed for Seattle Public Utilities’ Highline Wellfield project in the 1980s. These
figures are supplemented with additional well costs from projects completed for the City ofRenton and updated in 1997 for estimating Snoqualmie Aquifer transmission costs.
Treatment Costs
Each well was evaluated separately in terms of its instantaneous flow rate, average flowrate, and treatment requirements based on its water quality. Costs for each alternative weredeveloped based on the function of each well in the alternative. The following costs includeequipment, delivery and training cost. In addition, they include a 10% Contractor mark-up,30% installation costs, 25% electrical and I&C costs, and the 1.8 factor described previouslyto account for construction contingency and mitigation expenses, sales tax, and permitapplications, engineering, and financial/administrative costs. The cost per alternative
assumes that the treatment systems are constructed under one contract. Project phasing andmultiple contracts will result in higher capital costs, and these circumstances are notreflected in this estimate. The estimated costs were based on the following:
Chlorine disinfection project costs were obtained from Clor-tec on-site generationequipment. This consideration is not provided as an equipment recommendation.On-site sodium hypochlorite generation was used in this case due to its conservativecapital costs, though there are other viable disinfection alternatives. Additional costswere included for miscellaneous items such as injectors, static mixers, and transferpumps.
1 mg/L dose, 2 lbs/day$40,095
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UPDATED PROJECT COST ESTIMATES FOR CIP
1 mg/L dose, 6 lbs/day1 mg/L dose, 12 lbs/day1 mg/L dose, 24 lbs/day
$86,130$100,980$124,740
Fluoridation project costs were obtained from Acrison dry-sodium fluoride feedsystem. It includes a feeder/hopper, single door loader, 50 gallon dissolver w/mixer, level probes and valving, and a control panel. It does not include a dustcollection system. This consideration is not provided as an equipment
recommendation. A dry sodium fluoride feeder system was used in this case due toits reliability and conservative capital costs, though there are other viable
fluoridation alternatives. Additional costs were included for miscellaneous itemssuch as day tank, injector, and transfer pumps.
0-2000 gpm @ 1 mg/L dose$74,250
Manganese Sequestering project costs were obtained from SeaQuest equipment.This consideration is not provided as an equipment recommendation. This systemwas used in this case due to its conservative capital costs, though there are otherviable manganese sequestering alternatives. The system costs included here includesome automation including level sensors, which may be tied to the SCADA system.Less expensive systems could be implemented with out automation.
0-2000 gpm, treat max 0.046 mg/L Mn conc. with 0.65 ppm dose $29,700
Manganese Removal project costs were obtained from Culligan Greensand Filters.This consideration is not provided as an equipment recommendation. Green sandfiltration was used in this case due to its conservative capital costs. Costs were alsoadded to include backwash tank and pump, additional chlorine facilities formanganese oxidation, miscellaneous piping, blower, and startup services.
0-2000 gpm, treat max 0.135 mg/L Mn concentration$335,000
Membrane treatment (Alt 3.02) plant cost were based on CH2M HILL experiencewith similar sized membrane plants. $1/gallon treated was used with the 1.8 factorfor the capital cost of a 7 MGD membrane plant.
The treatment plants for Alts 2.01 and 6.01 for reuse were obtained from the Damesand Moore estimate used the original alternative analysis preformed for the DraftWater Plan. $3,000,000 per plant was used.
Backup for development of the above costs is included in the attached worksheets.
Operation and Maintenance Costs
O&M costs were derived for each costing category. These are annual costs, assumingoperation for 365 day/year, unless otherwise indicated.
Conveyance system or pipeline maintenance costs were assumed to be 0.50% of capitalcosts/year.
Pump station maintenance costs were assumed to be 1.00% of capital costs/year.
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UPDATED PROJECT COST ESTIMATES FOR CIP
Well/ASR maintenance costs were assumed to be based on the volume of waterpumped each year: $0.35 per hundred cubic feet.
Treatment O&M costs were evaluated separately for each well. They were based onchemical requirements (based on flow and dose) and labor hours required for systemmaintenance (cleaning, refilling, testing, etc.). Chemical costs were obtained fromchemical suppliers, labor costs were assumed to be $50/hour and include materials,tools and transportation.
O&M cost for the membrane filtration plant (Alt 3.02) were generated from previousCH2M HILL projects, which estimated the cost per gallon of a 2 MGD plantoperating 3 months a year ($0.64 /thousand gallons).
The O&M costs for treatment plants for Alts 2.01 and 6.01 for reuse were obtainedfrom the Dames and Moore estimate used the original alternative analysis
preformed for the Draft Water Plan. The plants operate 3 months/year at $1.80/ccf.
Reservoir maintenance costs were assumed to be 1.00% of capital costs/year. Thereservoir O&M costs for the Union Hill Tank were estimated to be 1.00% of the capitalcost for a new 2MG tank.
Backup for development of the above costs is included in the attached worksheets.
Miscellaneous Costs
Some alternatives included specialty items that were included as separate line items.
Alternative 3.02 required a 100 MG surface water impoundment and a 10 MGDtreatment plant.
The surface water impoundment was estimated at $ 4.32 million. The followingassumptions were made: 1) all materials were available on site, 2) the cut and fill
volumes were balanced, 3) a single membrane liner was used, 4) 12-inches of cushionmaterials was provided for the liner, 5) clearing, stripping and grubbing wasmoderately difficult, 6) the site was fenced, and 7) no extraordinary measures arerequired for its construction. The 1.8 factor described previously to account forconstruction contingency and mitigation expenses, sales tax, and permit
applications, engineering, and financial/administrative costs was applied. This costdoes not included land acquisition of a 40-acre site.
$100,000 was assumed as the cost of a complete pilot plant study for the membraneplant.
The South Connection with the Issaquah Pipeline via I-90 was assumed to be a 24-inchpipe located along the I-90 corridor, from the East Gate Reservoir to Well 9.
33,900 feet was the estimated length and the pipeline costs used in the ‘Pipelines’section of this tech memo was used to determine the total cost of the pipe. TheDistrict’s share of the pipe was determined based on it’s required ADD (5500 gpm)as a percentage of the maximum flow through the 24-inch pipe at 7 fps (approx10,000 gpm).
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UPDATED PROJECT COST ESTIMATES FOR CIP
The South Connection with the Issaquah Pipeline via Issaquah Highlands was assumedto be a new 12-inch line from Issaquah Highlands to the ‘Y’ and an upgraded pipe fromthe Holly and Phase II pump stations to Issaquah Highlands.
The estimate described above for the south connection of the Issaquah pipeline via I-90 was used for the main transmission line. The same pipe length was used for thisestimate since changes in the pipe routing from the East Gate Reservoir to IssaquahHighlands would most likely result in a similar length (33,900 feet of 24-inch pipe).9,200 feet was estimated as new 24” or 30” pipes (unplanned for Issaquah
Highlands) from the Issaquah Highlands. Pipeline costs used in the ‘Pipelines’section of this tech memo was used to determine the cost of this section of pipe.2,800 feet was estimated as upgraded pipe from the Holly and Phase II pump
stations to Issaquah Highlands (16” planned for Issaquah Highlands, but 24” or 30”required for this connection). The difference between these pipeline costs was usedas the linear foot costs for the Districts share of the pipeline costs.
Also, the Holly and Phase II pump stations would have to be upgraded to accountfor the additional 5500 flow to the Plateau. The difference between the planned flow(2241 gpm) and the required flow (2241+5500=7741 gpm) was used to determine thecost for the pump station upgrade. This cost was obtained from the ‘Pump Station’section of this memo.
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