design and construction of area 7 cedar hills regional landfill – lessons learned from economic...
TRANSCRIPT
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DESIGN AND CONSTRUCTION OF AREA 7
CEDAR HILLS REGIONAL LANDFILL – Lessons Learned from Economic
Conditions
Mizanur Rahman, Ph.D., PE, PMP
Senior Engineer and Project ManagerKing County Solid Waste Division
4/15/2011
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Presentation Outline
Overview of Cedar Hills Regional Landfill
Area 7 Development Summary
Pre-Design and Design Process
Bidding Process
Construction (Phase 1 and Phase 2)
Lessons Learned
Wrap-up/Questions
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• Population served - 1.3 million; • Landfill area: 920 acres of land• Southeast King County• Landfill operations began: Early 1960’s• 850,000 tons/year; approx 1.13 MCY of airspace consumed/year• Design capacity: 50-60 million tons • Capacity consumed: 33 million tons as of 2010• Estimated closure date : 2024
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CEDAR HILLS REGIONAL LANDFILL SITE MAP
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Area 7 Development Overview
• Area Developed: 18.6 acres• Design and CM budget: $2.9 million ; Construction: $10.01 million; • King County Project Management : $254K• Construction Contingency: $1.54 million• Design Began: February 2006 and Construction Completed: March 2010• Construction completed in 2 phases: 2008 and 2009-10
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Area 7 Phase 1 Construction
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Area 7 Phase 2 Construction
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Area 7 Commissioned
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Area 7 Grand Opening
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Area 7 Development Timeline
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2006 2007 2008 2009 2010
1 2 3 4 5 6 7 8 910 11 12 1 2 3 4 5 6 7 8 9
10 11 12 1 2 3 4 5 6 7 8 9
10 11 12 1 2 3 4 5 6 7 8 9
10 11 12 1 2 3 4
Pre-design (Initial Plan)
Pre-Design (Actual)
Detailed Design (Initial Plan)
Detailed Design (Phase 1 & Phase 2)
Bidding (Initial Plan )
Bidding (Phase 1 & Phase 2)
Construction (Initial Plan)
Construction (Phase 1 & Phase 2)
Planned
Actual
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King County Area 7 Development BudgetPrepared in 2005Based on escalating costs from 2003 bids
Engineer’s cost estimates were based on the average unit bid price of Area 6 development projects.
Cost estimates were prepared at 90% level only.
$3,269,344
$5,623,396
Phase I
Phase II
Total: $8,892,740 (incl. 10% contingency)
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Area 7 Phase 1 -2008 ConstructionBid Summary
Area 7 Partial Excavation (Schedule B)- 12 bid items5 bids submittedEngineer’s Estimate : $2,044,244 (Excl. Tax and Contingency)Lowest Bidder: $2,375,842Highest Bidder: $3,470,454Contract Awarded for : $2,811,156 (37.52% higher than
Engineer's Estimate) (Contract awarded to the bidder with lowest combined bid total for all
schedules)
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Phase 1 Construction Bid Items (Quote Comparison)
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Major Bid Items % of Total Estimate
Engineer's Unit Rate
$/CY
Bidder's Average
Rate ($/CY)
% change over Engineer's
Rate
Excavation and Haul to Main Stockpile 34.97% $2.00 $3.65 82.60%
Processing for Select Fill Materials 23.70% $4.27 $4.00 -6.32%
Select Fill Haul and Place in Area 5 Stockpile 9.24% $2.25 $4.35 93.33%
Screen 2" to 6" rock and place in Main Stockpile 8.88% $4.00 $4.99 24.75%
Crush 6" Over, Screen and place in Main Stockpile 8.33% $6.00 $8.90 48.33%
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2009 Area 7 Phase 2 Design ModificationsInitial Engineer’s Estimate: $9.68 millionsRevised Engineers Estimate: $8.42 millionDesign Modified @90% design level for the following items:
Reduce Drainage Layer Material (DLM) thickness from 24”to 18”
Owner excavate as much of the Area as possible
Eliminate the Contaminated Stormwater (CSW) Lagoon modifications
Revise the Area 7 temporary in-cell CSW lagoon
Use 60 mil HDPE geomembrane liner in lieu of 80 mil HDPE liner
Remove 22” landfill gas (LFG) sub-header from the bid package
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2009 Area 7 Phase 2 Construction
Area 7 Phase 2 Construction included:Remaining Excavation (394,000 cy)
Liner System Construction
Leachate collection
Initial Landfill Gas Collection
Stormwater management system
Contaminated Stormwater lagoon Expansion
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2009 Area 7 Phase 2 Construction (contd.) Total 62 bid items
10 bids submitted
Engineers Estimate: $8.38 million
Lowest Bidder’s Quote: $5.55 million
Highest Bidder’s Quote: $8.09 million
Contract Awarded for : $5.62 million (32.94% Lower than Engineer's)
(Contract awarded to the bidder with lowest combined bid total for all schedules)
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Materials Price Variation (Engineer’s Estimated Rate Vs. Bidder’s Rate)
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Bid Item Description % of Total Cost
Engineer's Unit Price
Bidders Avg. Rate
% Change over Engineer's Rate
Geotextile - Type 3 3.92% $2.91 $2.27 -21.95%
60 mil Textured HDPE Geomembrane 7.25% $5.38 $5.43 1.01%
Geosynthetic Clay Liner (GCL) 5.90% $4.38 $5.74 31.02%
HDPE pipes (6" to 24") 10.26% $26.67-$101.63 $20.36-$85.67 -16% to -40%
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Price Variation for Major Construction Items (Engineer’s Estimate Vs. Bidder’s Rate)
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Item Description% of Total
Cost Estimate
Engineer's Unit Rate
($)Bidder's Avg.
Rate ($)% Change over
Engineer's Rate
Crushed Surfacing Base Course 1.93% $22.76 $18.19 -20.06%
Excavation and Haul 18.60% $3.28 $2.94 -10.43%
Drainage Layer Material 22.43% $31.16 $25.01 -19.73%
Select Fill Processing 3.17% $7.00 $7.47 6.75%LFG Connection 2.99% $5,470 $1,936 -64.60%
LFG Sub-Header Riser Bank 4.78% $23,734 $3,092 -86.97%
Grass Lined Ditches 0.77% $11.52 $6.68 -41.98%Asphalt Lined Ditch -
Area 7 Perimeter 0.80% $27.58 $18.37 -33.41%
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Critical Bid Item for Phase 2 Construction
Drainage Layer Material (DLM): 22.43% of the total quote
Quote for DLM by Bidder (Contract Awarded): 39% lower than the engineers estimated rate
The DLM bid item was not critically evaluated with respect to its specifications and market price
An ambiguity in the DLM specification existed and was overlooked
Differences in interpreting the DLM specification led to a claim by the Contractor
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Lessons LearnedChanges in Economic Conditions had impacts on:
Construction services pricing;Bid materials pricing; Competition; Quality control; and Schedule delay
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Lessons Learned (Contd.)
Alternative engineering cost estimating technique is necessary and should include:
Baseline (30% design level) cost estimate based on historical cost data of similar projects
Update baseline cost estimate with design progression at (60%, 90%, and 100% level)
Verify and update the cost estimate with market conditions
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Lessons Learned (Contd.)
Benefits of alternative engineering cost estimating technique :Additional costs for design modification to meet
the budget goals could have avoided/mitigated at earlier stage
Critical bid items should be estimated more accurately
Gap between final cost estimate and the budget could be minimized at earlier stage of the design plan.
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Lessons Learned (Contd.)
Critical review of the bid items with high volume and high price tags during bid evaluation stage:Bid specifications of the critical bid items be evaluated for
market conditions
Bidder’s explanation on extremely low/high quoted items be sought at bid review session
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Lessons Learned (Contd.)
Additional costs incurred for:Reworking design plans to comply with budget ($67,000)
Preparing two bid packages ($175,000)
Claim for DLM specifications Changes ($465,000)
Support services for claim negotiation ($95,000)
Extended construction management , ($ 70,000) and
Extended county project management (Approx. $30,000).
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ConclusionsPerform 30%-60%-90% design within budget limits
Update cost estimate at 30%-60%-90% design level
Prepare budgets based on escalating old cost data as well as market condition
Engineer’s cost estimate should be updated and validated with market prices along with design progression
Allow for design improvements during construction
Use of mattress – an innovative technique for protecting DLM from soil clogging
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Area 7 Operations- Use of Mattress
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Area 7 Phase 2 Construction (Geomembrane Liner)
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Connection Between Area 6 and 7
Geomembrane Rolls Out on Area 7
Extrusion Welding on GeomembranePipe Booting with Geomembrane
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Manhole for Leachate Collection Initial Gas Pipeline Collector
Installing Penetration Box Areas 5 and 7 Leachate Tie-in