Ocean Outfalls

Water Treatment Plant Intake and Outfall Facility Decommissioning

Location: Ventura, California
Project Description
L123 was contracted to perform the decommissioning of a water treatment plant intake and outfall facility located on the California coastline north of the City of Ventura on a turnkey basis. This 50+ year old facility was used to pump seawater to inland oilfield related water flood operations and to discharge the filtered seawater back to the ocean. L123 conducted all technical surveys, research, and engineering and design of the decommissioning project as well as providing technical support and planning to the regulatory permitting process. The decommissioning scope of work included the recovery of two subsea pipeline end structures; recovery and disposal of two intake pipelines and a discharge pipeline running offshore from the vault; the removal and disposal of the pumps, piping and ancillary equipment from within the vault; the demolition of the vault to a depth of at least 5 feet below the beach sand level; the grouting and abandonment in place of the casing running under SR-1/Highway 101 and a railroad right-of-way; and the grouting and abandonment in place of the three pipelines running from the vault to the client facility north of Highway 101. Work performed with zero accidents/incidents.
 
Relevance
The successful completion of this project demonstrates L123’s ability to efficiently design, permit and execute construction and decommissioning of energy facilities on land and underwater in the tough California regulatory environment.

Municipal Wastewater Outfall Construction Project

Location: Cayucos, California
 
 
Project Description
Longitude 123 converted an ex-marine tanker berth 20-inch by 4,000-foot-long submarine pipeline into a casing for a 14-inch high density polyethylene (HDPE) outfall pipeline. L123 and the project team, planned, permitted and performed the project in just six months, meeting the client’s completion deadline. The short timeframe was a challenge complicated by California’s regulatory environment, seasonal sea state conditions, as well as designing and procuring custom materials and equipment. Project elements included engineering and design; regulatory permitting; pigging/flushing the submarine pipeline in support of the conversion; assembly of specialized tools and equipment to perform the pigging/flushing and follow-up construction work; assembly and installation of the 14-inch HDPE pipeline; and assembly, launching and installation of the outfall diffuser pipeline.
 
Relevance
This project reflects L123’s ability to plan, permit and perform turnkey California marine projects.

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.

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.