RNG M&R Station

Confidential Client Schuylkill County, PA

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Overview

An area natural gas utility (Utility) company contracted with Entech to provide a metering and regulation (M&R) receipt station as well as an 8” high pressure gas pipeline to transport renewable landfill (Landfill) natural gas (RNG) to market. Upstream of the Entech designed station and pipeline, the landfill gas is collected via a low-pressure system and processed to remove contaminants. Once processed, this transmission quality gas is compressed and delivered to the Entech designed station and pipeline for delivery to market.

Solution Details

Metering and Regulation

Entech worked closely with the natural gas utility to establish design solutions to satisfy the full range of this project’s operating parameters and functions. A station pad layout was developed to integrate with the existing landfill grading. Three-dimensional (3D) station modeling allowed our design team to produce multiple equipment arrangements to maximize station layout efficiencies in an easily presentable form. As a result, vehicle access is provided down the center of the facility, allowing clear access to all equipment and processes for operation, maintenance, and egress.

This station utilizes an inlet gas sampling and analyzer system tied directly to the station inlet shut-in isolation valve. This function was deemed critical to preventing station piping and equipment from encountering off-spec. gas,in the unlikely case of an upstream Landfill processing quality issue. Downstream of this shut-in control is an inlet coalescing filter/bypass and associated double-wall blowdown tank for any collected liquids.

Flow measurement is provided by a 6” ultrasonic meter located immediately upstream of the pressure/flow control. This control, provided by a parallel worker/monitor control valve, runs allowing redundant systems suitable for various operating conditions. Both gas metering and regulation are housed in separate buildings to prevent operational issues resulting from inclement weather.

In addition to the over-pressurization protection (OPP) provided by the worker/monitor control valves, a station pressure relief valve is provided for additional OPP. Odorization is provided immediately downstream of the station check valve to meet pipeline odorization requirements. Provisions to install an 8” launcher provides the ability to clean and monitor the integrity of the pipeline, which was sized to allow for future capacity increases or pressure reduction.

Pipeline

Entech worked closely with Utility engineering and land agents to evaluate and establish suitable pipeline routing, construction access and feature crossing methods for an approximately 45,400’ (8.6) mile, 8-inch steel gas pipeline. The line connected the Broad Mountain RNG processing skid to the client’s District Regulator Station. The design team provided design and permitting for a 75-foot-wide limit of disturbance for line construction and all associated erosion and sedimentation controls. Temporary rock construction access locations and details were provided to allow suitable construction access at multiple locations along the alignment.

Road and access crossing design details were provided to utilize open-cut methods of installations. The established ROW paralleled an existing electrical power line ROW, which created the need for increased cathodic protection and AC mitigation considerations. The Utility corrosion and integrity group worked closely with the Entech design team to accurately capture these integrity system components in the design drawings.

Throughout the detailed design process, Entech scheduled and hosted periodic video conference calls with project stakeholders. Those meetings included representatives of the Utility (Land, Environmental, Engineering and Management), Entech (Engineering, Project Management, and Designers). These meetings ensured smooth transfer of information and gave all parties the opportunity to get timely answers to questions.