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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.

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Presentation on theme: "DESIGN AND CONSTRUCTION OF AREA 7 CEDAR HILLS REGIONAL LANDFILL – Lessons Learned from Economic Conditions Mizanur Rahman, Ph.D., PE, PMP Senior Engineer."— Presentation transcript:

1 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 Manager King County Solid Waste Division 4/15/20111

2 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 4/15/20112

3 Population served million; Landfill area: 920 acres of land Southeast King County Landfill operations began: Early 1960s 850,000 tons/year; approx 1.13 MCY of airspace consumed/year Design capacity: million tons Capacity consumed: 33 million tons as of 2010 Estimated closure date : /15/20113

4 CEDAR HILLS REGIONAL LANDFILL SITE MAP 4/15/20114

5 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 /15/20115

6 Area 7 Phase 1 Construction 4/15/20116

7 Area 7 Phase 2 Construction 4/15/20117

8 Area 7 Commissioned 4/15/20118

9 Area 7 Grand Opening 4/15/20119

10 Area 7 Development Timeline 4/15/ 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

11 King County Area 7 Development Budget Prepared in 2005 Based on escalating costs from 2003 bids Engineers cost estimates were based on the average unit bid price of Area 6 development projects. Cost estimates were prepared at 90% level only. 4/15/201111

12 Area 7 Phase Construction Bid Summary Area 7 Partial Excavation (Schedule B)- 12 bid items 5 bids submitted Engineers Estimate : $2,044,244 (Excl. Tax and Contingency) Lowest Bidder: $2,375,842 Highest Bidder: $3,470,454 Contract 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) 4/15/201112

13 Phase 1 Construction Bid Items (Quote Comparison) 4/15/ 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%$2.00$ % Processing for Select Fill Materials 23.70%$4.27$ % Select Fill Haul and Place in Area 5 Stockpile 9.24%$2.25$ % Screen 2" to 6" rock and place in Main Stockpile 8.88%$4.00$ % Crush 6" Over, Screen and place in Main Stockpile 8.33%$6.00$ %

14 2009 Area 7 Phase 2 Design Modifications Initial Engineers Estimate: $9.68 millions Revised Engineers Estimate: $8.42 million Design design level for the following items: Reduce Drainage Layer Material (DLM) thickness from 24to 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 4/15/201114

15 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 4/15/201115

16 2009 Area 7 Phase 2 Construction (contd.) Total 62 bid items 10 bids submitted Engineers Estimate: $8.38 million Lowest Bidders Quote: $5.55 million Highest Bidders 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) 4/15/201116

17 Materials Price Variation (Engineers Estimated Rate Vs. Bidders Rate) 4/15/ Bid Item Description % of Total Cost Engineer's Unit Price Bidders Avg. Rate % Change over Engineer's Rate Geotextile - Type 33.92%$2.91$ % 60 mil Textured HDPE Geomembrane 7.25%$5.38$ % Geosynthetic Clay Liner (GCL) 5.90%$4.38$ % HDPE pipes (6" to 24")10.26% $ $ $20.36-$ % to -40%

18 Price Variation for Major Construction Items (Engineers Estimate Vs. Bidders Rate) 4/15/ 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%$22.76$ % Excavation and Haul18.60%$3.28$ % Drainage Layer Material22.43%$31.16$ % Select Fill Processing3.17%$7.00$ % LFG Connection2.99%$5,470$1, % LFG Sub-Header Riser Bank 4.78%$23,734$3, % Grass Lined Ditches0.77%$11.52$ % Asphalt Lined Ditch - Area 7 Perimeter 0.80%$27.58$ %

19 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 4/15/201119

20 Lessons Learned Changes in Economic Conditions had impacts on: Construction services pricing; Bid materials pricing; Competition; Quality control; and Schedule delay 4/15/201120

21 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 4/15/201121

22 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. 4/15/201122

23 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 Bidders explanation on extremely low/high quoted items be sought at bid review session 4/15/201123

24 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). 4/15/201124

25 Conclusions Perform 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 Engineers 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 4/15/201125

26 Area 7 Operations- Use of Mattress 4/15/201126

27 Questions??? Thank you! THANK YOU! 4/15/201127

28 Area 7 Phase 2 Construction (Geomembrane Liner) 4/15/ Connection Between Area 6 and 7 Geomembrane Rolls Out on Area 7 Extrusion Welding on Geomembrane Pipe Booting with Geomembrane

29 4/15/ Manhole for Leachate Collection Initial Gas Pipeline Collector Installing Penetration BoxAreas 5 and 7 Leachate Tie-in


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