Description of the Facility
The Facility will meet or exceed all relevant regulatory, design, and safety requirements. The Facility’s design, construction, and operation will have minimal impacts on the environment and the community. The Facility will consist of a prefabricated gas pretreatment system, a prefabricated liquefaction system, ten (10) standard shop-fabricated LNG storage tanks each with a volume of 100,000 gallons (working volume of 90,000 gallons), four prefabricated LNG truck-loading stations, a Supervisory Control and Data Acquisition (SCADA) system, and appropriate control, hazard detection, security and fire-protection systems. The limited, low-profile buildings on-site will include:
1) Control, Utilities, Maintenance, MCC/Electrical building;
2) Fire System Pump Structure;
3) Refrigeration Turbine/Compressor building;
4) Gas Pretreatment building; and
5) LNG truck loading station shelter.
A rendering of the proposed design of the Facility at the preferred site is provided as Figure 1.3-1.
The Facility will be fenced, with an automatic gate that provides access to the site from Route 20 (Sturbridge Road). During liquefaction operation, the Applicant expects to operate in three eight-hour shifts per day and up to three federal DOT-certified supervisors or operators will be on duty for each shift.
As described above, natural gas supply to the Facility will be delivered using a new interconnection line and meter station on the TGP interstate pipeline. The meter station will be installed in a prefabricated building adjacent to the existing TGP interstate pipeline, approximately 1.5 miles from the Facility. Each of the two existing TGP gas pipelines will be tapped in order to provide a redundant supply to the Facility. The meter station includes typical equipment, including a filter separator, valves, instrumentation, SCADA equipment, and enhanced communications equipment. The proposed interconnection main will feature state-of-the-art design and construction. Launcher receiver barrels will be located on both ends of the lateral to facilitate efficient maintenance and “smart” inspections.
While not all equipment selections have been finalized (negotiations with the engineering and construction contractors are ongoing), a natural gas pretreatment skid employing an amine plant is expected to be installed to remove CO2. The Applicant also expects to install a molecular sieve system to remove water from the pipeline gas in order to facilitate effective and efficient liquefaction. These technologies are well-established and have been employed successfully for decades at similar facilities.
Liquefaction will be performed using a double-turbo-expander system that employs nitrogen as a refrigerant to liquefy the natural gas. This technology is well-accepted, proven throughout the industry, employed at numerous facilities in Commonwealth and across the US, and provides substantial safety and reliability. Refrigerant-grade nitrogen is widely available and such systems are safe, easy to operate, and highly reliable.
The Facility’s LNG tanks will be designed in accordance with Section VIII, Division 1 of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and will meet the design requirements of the U.S. Department of Transportation’s regulations, 49 CFR Part 193, and the National Fire Protection Association (NFPA) standard 59A.
The tank impoundments, vapor fencing, and exclusion zones have been designed in accordance with 980 CMR 10; each tank will have a 150% volume impoundment along with a high-expansion foam system in the containment. The truck-loading spill impoundment system will employ a 15,000-gallon impoundment area consistent with 980 CMR 10.
The primary electric power feed to the unit-substation is a medium voltage, three-phase, 60 Hz power source that will be supplied and installed by the local electric utility. In the event of a loss of offsite power (utility power), there are two dedicated “stand-by” 250 kW emergency generators that would automatically start and provide power to all critical Facility components. Both of these generators are natural gas-fired and will provide an uninterruptible power supply to the SCADA system, control, monitoring, and safety systems as well as back-up lighting.
A water supply and a system for distributing and applying water is required for fire prevention and protection (NFPA 59A, 12.5.1). Consistent with experts’ recommendations, there will be a field-erected fire water storage tank on-site with associated pumps and piping to deliver adequate water supply throughout the site. Portable handheld dry chemical fire extinguishers will also be maintained throughout the Facility.
The layout of the equipment is proposed in accordance with the requisite setbacks and locations governed by NFPA 59A and 980 CMR 10.00. Importantly, all such exclusion “zones” are fully contained within the boundaries of the site. Structural concrete foundation components and any proposed internal roadways will be engineered and designed based on applicable design codes, generally accepted engineering practices, data developed in the field, and from geotechnical exploration and review.