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HomeMy WebLinkAboutAppendix D(2) - Site Plan Review Worksheet - NG ResponsesFormal Review SITE PLAN REVIEW COMMENT SHEET Date: December 2, 2025 Map: 98 Lot: 81 Applicant: Boston Gas Company d/b/a National Grid Location: 127 Whites Path, South Yarmouth Zone: B3/APD Persons Present: Project Summary Replacement of LNG Tank storing up to 2.1 million gallons liquified natural gas. Refer to Exhibits 2 through 10 for additional detail. Correction: National Grid proposes replacing the existing 2.1-million-gallon tank with a new 1.7-million-gallon tank. Comments Building: Project as proposed will require relief from the ZBA in the form of a SP for the use in the B3 and APO overlay. The height of the tank was referenced in discussion will likely require a variance. Original project was provided an exemption from the zoning bylaws in Jan. 1969 through decision #15972 and modified in Nov.1971 through decisions 15972A and 15972B. These decisions were specific to the existing conditions, which is the reason for the relief from the local ZBA. Having no prior relief from the ZBA, there are no existing decisions of the board to modify. Building permits required to demolish and construct new tank. Stormwater Management permit will be required from the Conservation Commission. Note: The Company disagrees with the interpretation that the referenced DPU zoning exemption Orders were specific to the existing conditions. The Orders expressly exempted the entire 29-acre “parcel of land” and “the liquefied natural gas processing, storage facilities and regasification equipment and related structures to be installed thereon”. This is consistent with the DPU’s broad authority under G.L. c. 40A, § 3 to exempt both “lands or structures” from local zoning. Further, the DPU ordered that its decision would remain effective “to the extent that [the land and facilities] may be used for or in connection with the processing, transportation, liquefaction and regasification and storage of natural gas”. So long as that condition is met, which it is here, then the DPU’s intent was for the zoning exemption to continue in effect for future projects. Notwithstanding, the Company has agreed to pursue local zoning approval to avoid further delay and conflict with the Town. Planning: For the ZBA, clearly outline the reasons explained at SPR for the needed height (88'), new tank location, clearing limits and tank containment within the new tank. Consider other locations for visualizations along the CCRT and Beacon Street neighborhood. Maximum 20' site lighting pole height, and footcandle requirements at property lines, per Section 301.4.10. Design Review: Not present. Conservation: The proposed project requires a stormwater management permit. Engineering: • Provide drainage calculations when available to review upon submission of Stormwater Management permit Refer to Stormwater Management Application for drainage calculations • Provide vapor fence detail Vapor fence is 10’ tall with Ultimate Privacy Slats (or equivalent) covering 90% of the fence surface area. • Confirm purpose of the fire access path on the exterior side of the fence. Provide truck turning movements on the site plan Lt Michael Oliva Bill Ciocca Joe Carroll Barry Lewis Brendan Maloney Mark Grylls Gary St, Fleur Kathy Williams Luke Poirier Amanda Lima Luke White Purpose of fire access path is to provide 360 degree fire truck access around perimeter of facility for emergency. Fire hydrants are spaced to provide complete coverage along fire access path with fire truck. Turns are based on Engine 43 specification provided by South Yarmouth Fire Department. Aerial Site Plan has been updated to indicate turning radii and depicting fire truck making turns. • Site plan appears to reflect the southwest part of the path just ends of vegetation and fire trucks exiting from the southwest side of the fire access path would have no way to exit (traveling clockwise). Please confirm the vehicle flow intent. Vehicle flow is intended to provide one way clockwise or counter-clockwise access. Southwest fire access path does not end in vegetation. The path turns north back into the facility behind control room. • Confirm what restoration will look like upon decommissioning of LNG tank After decommissioning the existing LNG Tank, TK-1, the LNG Tank and appurtenances (piping, valves, lightning antenna) will be demolished and removed. The site will be graded back to existing grade with a graveled surface. • Provide height and diameter of the existing and new tanks. Existing LNG Tank, TK-1 foundation is below grade within a dike, at approximately elevation 25’ NAVD88. Existing grade is approximately elevation 35’ NAVD88. Existing LNG Tank TK-1 is 41.5 feet tall to top edge of tank and 52.4 feet tall to top of concrete dome. TK-1 is 106.3 feet wide. Proposed LNG Tank T-1000 is a full containment LNG tank at grade, foundation at approximately 35’ NAVD88. The tank design has not been finalized; however, the Company anticipates that the final top-of-dome height will be under 100 feet above grade. T-1000 is approximately 90 feet wide. Fire: hot work requires permit. Fire watch personnel shall be assigned as needed by NG and the AHJ to determined by National Grid will obtain a hot work permit as the facility has done for compliance with past projects. Health: (Hazardous Materials) New LNG Tank • What is construction material of the 2.1-million-gallon full containment LNG storage tank? The inner tank will be constructed of 9% Nickel or Stainless Steel. The outer wall and dome will be steel-lined concrete. Construction materials are complaint with 49 CFR Part 193 – Liquefied Natural Gas Facilities: Federal Safety Standards and NFPA 59A – Standard for the Production, Storage, and handling of Liquefied Natural Gas for cryogenic service. • Does the LNG storage tank have a double wall to provide insulation? Yes, the proposed tank will be double walled with perlite insulation installed between the inner and outer tank to reduce heat transfer. • Does the double wall also serve as secondary containment in the event of a leak in the inner tank? Yes, the outer tank serves as secondary containment. Both the inner and outer tanks are independently able to contain the LNG stored. Full containment LNG tank construction is per NFPA 59A and API 620 – Design and Construction of large, Welded, Low-pressure Storage Tanks. • Does the LNG tank have an interstitial leak detection system between the inner and outer tank walls? Yes, the LNG Tank annular space will have temperature sensors to continuously monitor this space for a leak. Moats and Trenches • Will the new LNG tank be surrounded by a moat? No, the tank will be constructed at grade, there is no need for an earthen berm or any external containment due to the full containment design. This design and construction is compliant with NFPA 59A. If a moat is used, what is constructed from or lined with? n/a • What are the trenches from the tank to the impound area constructed from or lined with? Concrete • If the new LNG tank is not surrounded by a moat, how would a leak be directed to the trenches leading to the impound areas? The tank is a full containment design which is essentially a tank within a tank. The tank is designed so that a leak of the inner tank would be completely contained by the outer tank. The outer tank is the impoundment compliant with NFPA 59A. Piping • Is the LNG piping to the tank double-walled? No, the LNG piping is single-wall stainless steel wrapped in insulation for cold conservation and personnel protection. LNG piping will be routed inside a concrete trench, from the truck loading area to LNG tank and LNG tank to the vaporizers. A rupture would be contained within the trench and slope to the nearest impoundment. LNG piping located outside the trench, e.g., the section of pipe from the tank base to tank top, will be shrouded as required to satisfy 49 CFR Part 193.2059. Shrouding diffuses a release, reducing its momentum and preventing a vapor jet. Thermal sensors and UV/IR gas detectors in and around the shrouding will sense the hazard and safety systems will stop the process. Piping systems are compliant with NFPA 59A and ASME B31.3 – Process Piping. • Does LNG piping to the tank have a leak detection system? Yes, thermal sensors and UV/IR detectors are located strategically around the plant to detect releases of LNG and/or the presence of natural gas. • Is the LNG send out piping from the new tank double-walled? No, the same strategy from the first piping response above is utilized. • Does the LNG send out piping from the new tank have a leak detection system? Yes, thermal sensors and UV/IR detectors are located strategically around the plant to detect releases of LNG and/or the presence of natural gas. The Hazard Detection and Mitigation System is described in Section 3.7 of NFPA 59A Fire Protection Evaluation, 23510-POC-EVL-0040-0001. • Is all LNG piping aboveground? Yes, all LNG pipe is aboveground. • I understand from the National Grid NFPA 59A Fire Protection Evaluation, section 3.8.1 LNG and Liquid Nitrogen Spill Control, that all areas beneath LNG equipment and piping are curbed and graded to route any spills away from the equipment and into trenches that drain into local impoundment basins. Yes, liquid nitrogen impoundment is only provided beneath the Liquid Nitrogen Tank , liquid nitrogen is not conveyed elsewhere at the facility, only gaseous nitrogen via the vaporizer located adjacent to the Liquid Nitrogen Tank. Liquid Nitrogen • What is the capacity of the liquid nitrogen storage vessel? 3,150 gal • What is the capacity of the area surrounded by the concrete curb around the nitrogen equipment? The specific capacity will be determined during detailed design; however, at a minimum, it will be sized to contain the maximum inventory of liquid nitrogen stored. Impound Areas • What are the capacities of LNG impoundment basins S-6100 and S-6200? The impoundment basins are sized per and compliant with 980 CMR 10 – Siting of Intrastate Liquefied Natural Gas Storage and 49 CFR Part 193. S-6100 basin volume is 16,255gal (2,173ft3) S-6200 basin volume is 1,227gal (164ft3) • From what material are the impound areas constructed or lined with? Concrete LNG Release • In the event of an LNG release, would all liquid material be contained by or vaporize from, the impoundment basins without escaping to the environment and potentially impacting ground water? The liquid will be conveyed via the trench as it slopes to the nearest impoundment. Safety systems will detect the leak and minimize the spill duration. The spilled liquid will vaporize to atmosphere until it’s gone. The impoundments are full concrete basins and ground water will not be impacted. Water: Confirm the tie in of water main on east side of Whites Path. Also coordinate with vendor when the time comes to fill the tank with 1m gal. The 12” firewater main connection on the east side of the property will be confirmed upon contractor’s site verification period. The water department does not believe this main connects to the main on Whites Path. The proposed project does not introduce any additional firewater demand, so the existing system is adequate and the status of that 12” main carries no physical risk to the firewater supply. National Grid and our selected Contractor will coordinate with the Town well in advance of the hydrostatic test that will require upwards of 1 million gallons of water. We understand there may be seasonal and/or daily restrictions and will work with the Town to determine and adhere to these limitations.