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Paving in the High Desert

Paving in the High Desert. Edwards Air Force Base, CA Tri-Services Conference April 23, 2008. Overview. Project Scope DB Mentality The Team Design Precepts Construction Challenges Guiding Precepts. Temp Water Line. Batch Plant. Main Runway. Pug Mill. Temporary Runway.

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Paving in the High Desert

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  1. Paving in the High Desert Edwards Air Force Base, CA Tri-Services Conference April 23, 2008

  2. Overview • Project Scope • DB Mentality • The Team • Design Precepts • Construction Challenges • Guiding Precepts

  3. Temp Water Line Batch Plant Main Runway Pug Mill Temporary Runway Taxiway B Intersection Taxiway C Intersection Taxiway A Intersection New Power Check Pads New East Arm/ Dearm Apron Edwards Project Layout Dry Lake Bed Taxiway G

  4. CH2M HILL/IHC JV Team • Combines CH2M HILL innovation with IHC PCC paving expertise • Represents: • 60 years in federal work experience • Expertise in managing complex construction operations • Specializes airfield pavements on high-security sites • Nationally recognized aviation design expertise…ASR, PCASE, technology • Recent Airfield pavement projects valued over $300 Million • Projects received the “Best PCC Pavement Constructed in the USA” in Military/Commercial Aviation categories • #1 program management • #1 construction management-for-fee • #8 design-build management • Full service EPC integration worldwide

  5. Integrated Design Build Team • Sprit of Collaboration… Base on Trust • Always Focus on the Problem… no blame! • Meet Early and Often… High Communication • Open Book… Tell Motivation and Disclose • Level of Care… Code, Laws, Agency • Always Align Expectation of Owner Design can’t Make a Decision without Constructability Review Builders Can’t Make a Decision without Design Standard Check

  6. Open Book Mentality • Focus on the Problem…not Your own team • Contingency Funds • Unstable Conditions • Schedule Changes • Stake Holder Info Flow • “You Suck”– Weekly • QC Reconciliation Reviews

  7. Edwards AFB Definition Success Performance Schedule Cost Taxiway Openings Flight Transition to Temp Performance Period LD = $8000/day No ASR Meet Loading Flight Operations Environmental Runway Sustainability Program Amount Funding Per FY Manage to Cost

  8. The Plan!!

  9. Design Impact • Innovations introduced early when influence on outcome was high • Design had free access to Edwards and USACE • Allowed quick exchange of ideas and approvals • Internal team constructability meetings from Day 1

  10. Edwards High Desert Conditions • Mojave Desert, 100 miles NE of Los Angeles • Elevation of Base 2,300’ • Average rainfall 6”/year, (Jan, Feb, Mar) = 4” • Summer average daily max 94 degrees • Summer high 110 degrees • Windy days are common mostly out of NW • Sustained 15 to 30 MPH, • Gusts of 60 to 70 MPH

  11. Temporary Runway • PCC 1,000’ each end and Taxiway B • Asphalt remainder • Asphalt 1,000’ overruns, CTS shoulders • Sheet drainage to 200’ off centerline • New stake mounted R/W edge lights • Balanced earthwork varying elevation of centerline profile & 3 T/W tie-ins • Used unsuitable in lower fill

  12. Main Runway • Existing PCC has ASR, 1953 construction • Remove and replace PCC • Add drainage layer and underdrain system • Remove edge lights (18” off edge) and replace for paving track • Remove 6” of existing subgrade for new pavement section • 5 new plate load tests to verify subgrade

  13. Temporary Pavement Design • 20 year traffic reduced to 2 years in RFP • Traffic Areas A, C and D • PCASE used for thickness design • Different asphalt/PCC and base thickness based on traffic area • PCC flexural required 650, raised to 700 based on production 90 day breaks • Reduce PCC thickness accordingly

  14. Temporary Runway

  15. Main Pavement Design • Given 20-year traffic • Originally used 650 flex, changed to 700 and reduced thickness • Traffic Areas Type A, C and D • PCASE used for design thickness • Different PCC/Base thickness based on Traffic type and drainage layer • USACE k of 250, low CBR’s, verify with new Plate Load Tests when closed

  16. Main Runway

  17. Concrete Mix Design • Mix design flexural beams didn’t show gain until 56 days • Production mix gained much higher than mix design • Using close to the minimum cement factor for durability • Higher strengths are just happening

  18. PCC Strength

  19. Taxiway B Bypass • drawing showing Bypass

  20. Taxiway B Bypass • Allowed 2 taxiways (A and B) to be closed • Designed asphalt for 60 days, hottest months • Reduced traffic for use in PCASE • Optimized pavement section by using mechanistic software • Concerned about “punching” and rutting • Restricted B-52’s and Space Shuttle • Asphalt 4”, Base 7” • Performed fine, no rutting

  21. Innovations • Taxiway B Bypass • Grading Material Handling Plan • Grading models directly from designer to GPS on earthmoving equipment • Tracking on PCC early based on Zero Fatigue Curve Calculation edge stress • On-site computer server for rapid data exchange, QC survey • No earthwork as-built survey, used models

  22. Earthwork Affected Pavement • Pre-watered the excavation areas • Used an irrigation system • Encountered some unsuitable (SC, CL,CH) and some unstable • Required one footof suitable underpavement section

  23. Asphalt Paving Challenges • Crushed aggregate base through pug mill to add moisture • Required 2 lifts, some delamination and drying out • Approved to install inone lift • Hot summer temperaturesdidn’t allow asphalt to cooldown for compaction

  24. Concrete Challenges • Hot summer temperatures required starting early, 5 AM most days • Wind generally doesn’t start until after noon, so paving stopped

  25. Aggregate Challenges • Limited good pits for concrete aggregates • Production limited for simultaneous use of concrete, asphalt, base and drainable base • Some ASR, but mitigated with 15% Type F fly ash

  26. Material Tests • Cement tested in lab • Fly ash tested in lab • Asphalt oil tested in lab • Purpose to verify vendor’s certificates

  27. Construction Challenges • Earthwork shrinkage more than anticipated • Phasing of paving and lighting • Asphalt compaction • All work stops when winds over 25 knots (30 MPH)

  28. Value Drivers Flight Ops Pavement Quality - ASR Environmental Open Communication Inclusive Decision-Making Project Performance Time/Budget Force Protection Safety Security Guiding Precepts TAXIWAY C TEMPORARY RUNWAY TAXIWAY B MAIN RUNWAY 04/22 TAXIWAY A

  29. Questions

  30. Design Portion of D/B • Design was an integrated member of the JV team • Design was not a subcontractor or a subconsultant to the contractor • Innovation and efficiency was expected and achieved • No hidden agendas between design and construction • Ideas were freely exchanged

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