Ocean Outfalls

San Elijo Joint Powers Authority Outfall Stabilization Project

Location: Carlsbad, California
Project Description
This project involved the stabilization of a reinforced concrete outfall pipeline offshore Carlsbad, California. Approximately 2,000 feet of this 48-inch diameter pipeline was precariously suspended above the seafloor and required stabilization. The project site spanned an active surf zone. Environmental restrictions precluded the use of beach or shore-based support systems such as a trestle or pier, and the surf zone was too active to permit the use of floating equipment. L123’s owner, Mark Steffy, conceived and developed the Surf Sled II support system. Steffy also conceived and directed the design of a unique pipe support system. After soliciting 71 engineering firms nationwide, and reviewing a short list of eight responses, the Surf Sled approach was judged by the owner to be the most practical, safe and economical solution. According to the client, the project concept and execution saved the client over $20 million dollars. The surf sled used on this project was the second of three surf sleds designed, constructed and operated by Mark Steffy. The project was the subject of multiple technical papers, articles in trade journals, and presentations.
 
Relevance
This project demonstrates the ability of L123 to plan and execute major pipeline work in a nearshore or surf zone condition. It also demonstrates the ability of L123 to conceptualize and execute solutions to challenging underwater project requirements.

Pemex Dos Bocas 24-inch Diameter Outfall Construction Project

Location: Paraiso, Tabasco, Mexico

Project Description
This project was highly challenging due to the length (2.2-kms) and weight (approx 1,500-tons) of the pipeline, the dynamic coastal environment in which it was installed (coastal surf zone), the offshore water depths involved (excess of 20-m), the substantial project administrative support required by Pemex procedures, and the location of the work to very sensitive nearby existing Pemex pipeline infrastructure (three 36-inch export pipelines and five 48-inch diameter field pipelines). The HDPE outfall pipeline was pre-assembled in ten sections onshore and then pulled offshore in two extended operations (beach-pull). The actual marine installation required extensive around-the-clock operations involving over 250 skilled workers split into two offshore crews and two onshore crews. Final assembly involved fusing together the ten sections, installation of concrete ballast weights, and installation of flotation. The pipeline installation methodology was based on floating the pipeline into position and then flooding and sinking the pipeline. The pipeline was launched from the shoreline using a rail system. Pemex is the Mexican national oil company. ARB-Arendal is a Mexican pipeline company with an American corporate partner. ARB-Arendal performs in excess of $100,000,000 USD of pipeline construction annually in Mexico.

Relevance
This project demonstrates the ability of L123 to successfully plan and execute difficult marine construction projects in challenging conditions.

Power Station Tanker Berth Decommissioning Planning

Location: Carlsbad, California
 
 
Project Description
L123 managed all decommissioning technical planning services on this project including site characterization, informal scoping, engineering and design, production of project execution plan and permitting support. The project involved the decommissioning of a 20-inch fuel oil submarine pipeline and tanker berth facilities both onshore and offshore.
 
 
Relevance
This project demonstrates L123’s experience with marine construction and decommissioning planning and operations in a difficult environmental permitting setting.

Outfall Repair Project

Location: Oxnard, California
 
 
Project Description
In 1986 the City of Oxnard discovered a large leak in their 24-inch wastewater outfall pipeline. This reinforced concrete pipe outfall had been constructed decades before and little was known about its underwater condition. L123 owner, Mark Steffy, was contacted by the City of Oxnard and performed a dye test to locate the leak which was found to be in the middle of a very active surf zone and buried 5 feet or more below the sand seafloor. In response to this repair requirement, Mark Steffy designed and fabricated the first Surf Sled (Surf Sled I) along with aportable cofferdam. This skid mounted structure was designed for launch from a support vessel moored offshore, towed into the surf zone with a bulldozer operating from the shoreline, and pinned to the seafloor over the leak with pin-piling jetted in on each corner of the surf sled. The cofferdam was then lowered into position from inside the surf sled as built-in air lifts excavated around the pipeline. Once excavated the broken area was exposed and the repair made within 24 hours of the start. This project was the source of two technical papers.
 
 
Relevance
This project demonstrates L123 ability to innovate and adapt to meet client requirements.