DESIGN AND CONSTRUCTION OF AREA 7 CEDAR HILLS REGIONAL LANDFILL – Lessons Learned from Economic...

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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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Questions???

Thank you!THANK YOU!mizanur.rahman@kingcounty.gov

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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