St. John's River Crossing Design Build

• LocationJacksonville, Florida
• TimelineJune - August 2012
• Construction
  MethodsDesign-build
  Horizontal Directional Drilling (HDD)
  Pilot hole intersect

Scope

Michels completed a complex design-build construction project for the Jacksonville Electric Authority performing horizontal directional drilling (HDD), reaming and pullback operations for a 36” steel water main that spanned 6,575’. The alignment included two vertical curves and three horizontal curves in a congested area on a critical path timeline.


The project was constructed along the Arlington Expressway, a major east-west artery to downtown Jacksonville and the Jaguars football stadium. Months prior to construction the design-build team conducted daily meetings with key Florida Department of Transportation and local emergency management to develop a traffic and lane closure plan to consider peak traffic flows and allow safe and efficient construction. Once the project started, morning meetings initiated the next phase of traffic control each day. Much time was put into selecting the safest working environment for commuters and contractors alike.


Michels performed site preparation, pipe welding, coating, testing and HDD pullback assistance. The 36” steel pipe conformed to ASTM A-139 Longitudinally Seamed Grade C specs, and coating conformed to AWWA specifications that required 12-16 mils FBE 3M6233 ID and 12 mils FBE 3M6233 OD coating and 80 mils of Powercrete J ARO coating over exterior FBE.


Michels HDD operations began on the entry side with installation of about 160’ of 60” diameter steel containment casing and continued with installation of 200’ of 60” diameter steel casing on the exit side. The casings protected an existing 42” storm sewer that ran parallel to and eventually crossed above the proposed HDD alignment. A pilot hole intersect was performed under the river to reduce the downhole pressure of drilling.


Multiple strings of 36” water main were prestaged in three medians along the expressway between congested on/off ramps. A hard rock layer near the exit end of the crossing and several geometric design constraints presented unique challenges. The pull assembly was modified to achieve the successful combination of equipment, HDD tooling and pipe buoyancy control. The Herrenknecht 300T Thruster helped install the water main. It has a thrust and pulling force of up to 750 tonnes and is best for installing large diameter pipe in challenging geological conditions.


Michels crews worked 24 hours/day to complete six tie-in welds and the HDD pipe installation once the ramps were closed and had the ramps reopened within 10 days. The project was completed months ahead of the NFL season, which was the critical completion date.