Waterproofing for the Washington Weather
Washington residents can thank the climate for the lush green foliage, but roads and bridges don’t share their enthusiasm. The wet weather is a bane to the state’s travel infrastructure, plaguing the pavement with perpetual potholes and other problems. The state’s continued population growth (now 7.4 million) also poses challenges, as vehicles crowd the highways, especially in metropolitan areas.
With the area’s average annual 90 days of sunshine, there are only brief opportunities for repairs. Making the most of the state’s funding packages (i.e., Connecting Washington, the “Nickel” Funding program, etc.) is imperative in supporting the transportation system and preserving critical infrastructure.
The westbound, three-mile stretch across the US 2/I-5 Interchange from Bickford Avenue was in particular need. A valuable pipeline for business and commuting, the bridged area transported an average of 22,000 vehicles daily. Yet it hadn’t been paved for 16 years, putting it far past its useful life. Potholes, ruts, and uneven surfacing resulted in pooling water that not only jeopardized driver safety, but also threatened to destroy the concrete decking.
Weekday closures would be problematic, as added traffic on alternate routes could gridlock the area. The Washington State Department of Transportation (WSDOT) needed a solution that would be long lasting while overcoming the logistical hurdles.
Having completed the eastbound paving a few years prior, WSDOT now solicited bids for its counterpart. The westbound project would be more complex, costing nearly $11.6 million for necessary repairs. The venture would include the application of 536,000 square feet of geosynthetics, one of the largest quantities used by WSDOT for a single waterproofing project.
The DOT’s Standard Specifications for Road, Bridge, and Municipal Construction called for non-woven geosynthetic materials to exhibit 150 lb. min. tear strength (ASTM D4533), 200 lb. min. grab tensile strength (ASTM D4632), and 220 lb. min puncture resistance (ASTM D6241).
Project planning and design also would be complicated. To avoid commuter interruptions, full closures to allow work could occur only on weekends (7 p.m. Friday to 4 a.m. Monday) when the westbound lanes could be completely shut off to traffic. The dark would affect visibility and potentially productivity. Rain or precipitation could also cause delays, as no work could be done in wet weather. Additionally, crews of 15 to 25 workers (versus the typical 3 to 6) would be required to meet the massive manual application needs.
Selected primary contractor, Lakeside Industries, had managed a number of paving projects for the state, partnering with Jonnic Construction to do the underlying waterproofing membrane. The crews would collaborate once again, facing the new challenges head-on.
Jonnic chose Crafco GeoTac HS, a high-strength, peel-and-stick waterproofing membrane composed of fully modified SBS asphalt mastic on non-woven polyester geotextiles. GeoTac HS is proven to seal out moisture from concrete or asphalt surfaces while dispersing stress associated with reflective cracking. In addition to providing a more rigid structure that makes it easier to peel, Crafco GeoTac HS achieves nearly twice the required ratings for all three WSDOT-required ASTM standards and those of competitor products.
A long-time customer, Jonnic also looked to leverage Crafco’s agile delivery network and tap its field engineering and troubleshooting support to ensure against any downtime.
With significant deterioration evident, the teams started by breaking up the existing asphalt with excavators, cleaning/blowing off the deck, and tearing off the old membrane ¬-— with shovels and by hand. With the surface prepared, the teams attached 55-gallon drums of Crafco Asphalt Primer to pumps, spraying evenly on the area. They then rolled out the 48″ GeoTac HS across the centre, managing the more meticulous edgework with 12″ GeoTac HS rolls.
While typical geo-composite installs require hot mastic to be laid down between the 1-1/2″ overlapped seams, Crafco engineers pretested the GeoTac HS fabrics, finding that a 4″ overlap would sufficiently seal out moisture and debris when the HMA was applied. This not only resulted in significant savings in man-hours and materials, but helped the teams speed productivity by eliminating extraneous equipment. Thus, the teams were able to stay on task, installing 20,000 to 100,000 feet of GeoTac HS membrane per shift.
Once installed, Jonnic used Lakeside’s pneumatic, rubber-tired asphalt roller already at the site to press the material down and eliminate bubbles. The uniformity of the Crafco geo-composite and this rolling process ensured a solid waterproofing base. A single lift of 2.5″ HMA (the recommended minimum) was applied the morning after each shift, extending traffic lockout till it fully dried to ensure optimum results.
Now 66% complete, the US 2/I-5 Interchange to Bickford Avenue project has shut down for the winter. As weather permits, the teams will wrap up in the spring. As they begin, they will need to cut back the edges, re-prime, and do a GeoTac HS overlap to properly stabilize the new pavement joint connections with the pavement laid down before winter.
Because of its size and complexity, the US 2/I-5 Interchange to Bickford Avenue project will serve as a model for future WSDOT pavement preservation initiatives. Crafco GeoTac HS waterproofing membrane is expected to dramatically reduce long-term maintenance costs and extend service life. More important, it will provide the foundations for a thoroughfare that allows safer travels for residents of the Evergreen State and improved quality of life.