Makai has been designing and working with deep water pipelines since 1979 and has designed a number of down-the-slope polyethylene intake pipelines and suspended pipelines.
These large pipelines are suitedfor:

Numerous firms place pipelines on the ocean floor – usually at great expense. Makai’s design services lead to reduced cost by assembling the pipe onshore where labor costs are lower. The assembled floating pipe is towed into place and mounted to the seabed – often in a single day – minimizing expensive marine construction and weather-related risks. 

Installing these unique deep pipes can place substantial loads on the pipe assembly during installation.  Makai conducts field research studying the installation and loading on large diameter pipelines – both deep and shallow.  Makai also develops and tests the procedures needed to accommodate these loads. Here, a 1:5 scale model of a 55" pipe and custom flange assembly is measured while it is pressurized, tensioned and severely bent. 

Makai’s experience in pipeline design, analysis and deployment is summarized below:

 1.  55"Aquaculture and OTEC Pipeline  –  Makai was the construction manager and designer for the 55" diameter pipelines for the Hawaii Ocean Science Technology Park (HOST Park) at Keahole Point, Hawaii. This 3000′ deep, two-mile-long pipeline is the world’s largest and deepest cold-water pipeline, furnishing 27,000 gpm of 4°C water, and also 40,000 gpm of warm water via a unique pump station.. The award-winning pipelines were installed system during 2001.

enwave3pipe.gif (75163 bytes)

2. Toronto Deep Lake Water Cooling Pipes   –  Makai performed significant design aspects for the three deep water intakes for ENWAVE’s Deep Lake Water Cooling Project in Lake Ontario.  The deep (115 meter) intakes will provide cold water for air-conditioning buildings in downtown Toronto and  the municipal drinking water system. The new system will provide water of higher purity than is provided by the current intakes that obtain water from shallower depths.  Each HDPE pipeline is five km long and 1.6m (63") in diameter . The pipelines were installed during the summer of 2003. 

3. Joint Kimberly-Clark and City of Everett WA 63" Outfall Pipeline  –   Makai designed the new 63" diameter, 2700 ft long marine outfall pipeline for the Kimberly- Clark company.  

Lake Source Cooling Logo

4.  Cornell University Lake Source Cooling  –  Makai was selected by Cornell University to design a 63″ diameter HDPE intake and a 48″ diameter outfall pipeline in Cayuga Lake, NY to provide 20,000 tons of centralized cooling for the university. The intake pipeline is two miles long with an intake at 250′ depth. The pipeline provides 32,000 gpm of cold water and has a 75 year lifetime.  The system has been operating since 2000 and has cut electricity needed for air conditioning by 87%.  Click Here for a description of cold Seawater Air Conditioning

5. Indian OTEC Pipeline  –  Makai has provided conceptual designs and design guidance to the National Institute of Ocean Technology (NIOT) in Madras, India, for an Ocean Thermal Energy Conversion (OTEC) intake pipeline and mooring system for a floating OTEC research barge in the Indian Ocean. This pipeline will be 1 meter in diameter and will provide water from a 1000 meter depth.

6.  40" Pipeline Design and Installation  –  In a project with R.M. Towill Corporation, funded by the State of Hawaii and the U.S. Department of Energy, Makai designed a 40" polyethylene cold water pipe to be used jointly by the Natural Energy Laboratory and the Hawaii Ocean Science and Technology (HOST) Park sites on the Big Island. It is the largest deep-water intake pipeline in the world. This pipe is a larger and more rugged version of the previous MOE 12" pipe design at NELH and includes a 3000′ long buoyant section. Makai assisted in the deployment of this pipe to a depth of 2200′ in August, 1987. It is currently the main source of water for the Natural Energy Laboratory.

7.  Long-Operating OTEC Cold-water Pipeline  –  Makai conceived, designed and managed the construction of an experimental, down-the-slope polyethylene OTEC pipeline, 12" in diameter, for the State of Hawaii. This one-mile long pipeline has an intake at 2000′ and utilizes a unique 3000′ long free-floating catenary section to avoid contact with the steep, rocky bottom. The pipeline was installed in 1981 off Keahole Point, Hawaii. In spite of its "temporary" design life of 2 years, it survived many major storms including a hurricane and was operational for over twelve years.

8. 18"Cold-water Pipeline  –  Makai designed and provided construction management for an 18" down-the-slope cold water intake at the Natural Energy Laboratory of Hawaii. The purpose of this pipeline was to install, at a minimum cost, a reliable deep-water intake system to 2000′. This polyethylene design differs from previous NELH pipelines in that the deep-water pipe is buoyed approximately 40′ off the bottom on a series of pendants, the deployment was accomplished without major offshore equipment, and fabricated fittings were minimized. This pipeline was successfully deployed in October, 1987, and is still operational.

9.  OTEC Pipeline Research, Down-the-Slope Test  –  Working under a subcontract to Hawaiian Dredging and Construction, on a NOAA/DOE program, Makai was responsible for the concept development, design and deployment planning for an 8′ diameter down-the-slope OTEC pipe test. Part of the test was the demonstration of diver-free installation techniques suitable for very deep, large diameter pipelines on the steep, 42 degree slope. The concept included a flexible pipe joint that conformed to the bathymetry. Pipe deployment was successfully accomplished as planned using heavy lift barges and closed-circuit underwater television. The design included instrumentation for the measurement of hydrodynamic loads on the pipe after installation. Makai subsequently analyzed the hydrodynamic data from this test project.

10.  Four Outfalls inAmerican Samoa 

Tafuna Outfall:  This polyethylene pipeline installed in 1996, is 24″ in diameter, 1500′ in length and extends from the shoreline to a depth of 95′. The pipeline is anchored along its entire length for protection against frequent hurricanes and the large waves and strong currents that accompany them. The anchoring systems used were a combination of rock bolts and Manta Ray sand embedment anchors.

Utulei Outfall:  This was a very challenging pipeline design and installation because of the extreme slope that existed along the course of the pipeline. The outfall pipeline is 24″ in diameter, 350′ in length, and it begins at the reef edge at a depth of 5′ and plunges to a depth of 165′. The pipeline has a free floating catenary section that spans the steep slope, and it is heavily anchored at the bottom in deep water.

Aunu’u Outfall:  This is a 6″ outfall, 400′ in length, designed to serve a small community of approximately 400 people. It is installed across a heavily exposed reef flat which is subject to high waves and currents. The pipeline is partially buried and is anchored to the reef with rock bolts.

Pago Pago:  In 1991, Makai designed and managed the construction of a long, medium depth outfall in Pago Pago Harbor, American Samoa. This 16" polyethylene pipeline is 8500′ long and discharges near the mouth of the harbor at 176′ depth. It carries waste water from the Starkist Samoa and the Samoa Packing Tuna Canneries. The pipeline was installed using the controlled submergence techniques and was accurately laid on a curved route along the edge of the harbor. Concrete covers were designed to protect the pipeline at isolated locations from ship anchors and harbor traffic. The lifetime of the pipeline was maximized by minimizing the use of exposed metallic parts in the underwater construction. The pipeline was designed and installed in a short period and was completed ahead of schedule and well under budget.

11.  OTEC Soft Pipe  –  As a subcontractor to Marine Development Associates for a Solar Energy Research Institute funded program, Makai was responsible for the conceptual design and deployment plan for an innovative, low cost, 19′ diameter OTEC cold water pipe. This design involved a flexible fabric pipe that would approach the goal of fabrication and installation for less than $1,000 per meter of length per meter of diameter.

12.  Offshore OTEC8’PipeTest  –  As a subcontractor, Makai worked with Hawaiian Dredging and Construction on a NOAA/DOE program to dynamically test a suspended l/3 scale OTEC cold water pipe. Makai designed the mooring in 1300′ of water, developed the deployment plans, and assisted in the pipe design. This fiberglass reinforced pipeline was 8′ in diameter and 400′ long.

13.  Nearshore Water Intakes  –  Makai designed a warm water intake system for OTEC research in the state of Hawaii. The system provides up to 2000 gpm of warm open-ocean water at a constant head to the laboratory. The twin intake, multiple pump and highly redundant system was designed for high reliability. This work was done at the Natural Energy Laboratory, Keahole Pt., Hawaii for the Research Corporation of the University of Hawaii.

A second warm water intake was designed with the 40" HOST pipeline  This warm water intake provides 9,500 gpm for OTEC research and aquaculture.

A considerably larger shoreline intake has been designed to provide over 40,000 gpm warm water to NELHA. This design includes tunneling through the shoreline (construction completed) and a low cost pumping station on shore using vertical turbine pumps in individual well structures as opposed to a large pump sump.

14. Mini-OTEC –  Makai engineered several portions of the Mini-OTEC project – a full demonstration of Ocean Thermal Energy Conversion jointly funded by the State of Hawaii, Lockheed, Dillingham and Alfa Laval. Makai designed a 2′ diameter polyethylene pipe which served not only as an intake pipe from a 2000′ depth, but also as the "mooring line" for the 120′ x 35′ barge. Mini-OTEC was deployed in 1979 and became the first OTEC plant to produce net power. In the following year, the National Society of Professional Engineers awarded Mini-OTEC as being one of the ten outstanding engineering achievements in the United States that year.

15.  Cold-Water Pipe Research  –  Deep-water pipeline technology advancement is important at Makai. We have continued to develop improved methods of designing and deploying larger and deeper pipelines.

Makai has been involved in testing and evaluating pipeline materials relative to long term applications and deployment. Obtaining the maximum and safe performance from a pipeline is a key objective of any design and one that frequently requires research and testing to push pipeline materials beyond their familiar uses.

Makai has taken the pipeline deployment concepts that proved successful in actual installations and applied them to much larger pipelines. Pipelines in the range of 10′ to 12′ in diameter have been conceptually designed to be deployed quickly and economically.

The need to lower huge anchoring masses is a deployment obstacle with large pipelines. Makai has developed and tested "lightweight" anchors that simplify this deployment process.

Continuing work on warm water intakes lines has led toward the development of an easily installed pipeline hold-down system that firmly anchors the pipeline to the seafloor. Pipelines at Keahole Pt. are capable of withstanding a 50′ design wave. Such seafloor attachment systems are applicable to large and small pipelines in any service.

For more information and pricing, contact: