Environmental Engineering and Contracting

Arroyo Geoscience Inc., Geotechnical Engineering, Glendale, CA
Arroyo Geoscience Inc., Geotechnical Engineering, Glendale, CA

Office: 818-967-5977

A-HAZ Engineering Contractor Lic. No. 1062092

The Methane Mitigation Process in Land Development: A Step-by-Step Guide

The process of mitigating methane involves preventing the danger of explosions in buildings due to harmful soil vapor intrusion.
Methane Mitigation System Construction by Arroy Geo

The process of mitigating methane involves preventing the danger of explosions in buildings due to harmful soil vapor intrusion. This intrusion occurs when subterranean gasses naturally seep upwards into structures. When buildings are situated over contaminated soils, chemicals from below transition from a liquid to a vapor state, infiltrating the building. These gasses follow the easiest path, often through the tiny fissures and joints that are a common feature in concrete slabs. Methane, being colorless and odorless, accumulates undetected, leaving occupants unaware of its presence.

Public Works Los Angeles County

Managing Methane Zones in Land Development

For land developers, the obligation to address soil vapor issues is often unwelcome news, especially when a project falls within a methane zone. Many developers recognize the methane mitigation process as both time-consuming and expensive. Yet, they also acknowledge its critical importance for ensuring the safety of occupants, making it an indisputable necessity. Advancements in technology and increased awareness are leading regulatory bodies to better understand the health and safety implications. Consequently, environmental and health and safety regulations are continually evolving, contributing to a safer and healthier future in America.

Initial Step – Conducting Methane Testing

For developers involved in methane mitigation, the initial step often involves testing for subterranean methane soil gas. This procedure typically includes drilling on the property and setting up soil vapor probes for sample collection. These samples are gathered over a 24 to 48-hour period under the supervision of a professional geologist. In some areas, the outcome of these tests might even negate the need for further methane mitigation. Alternatively, they can help fine-tune the mitigation system design, aiding developers in minimizing costs and effort while complying with local regulations.

Methane Testing Report Review and Approval
The final methane testing reports must be submitted to the relevant local building department or methane mitigation authority. These reports are subject to a thorough examination by agency reviewers and might require adjustments or modifications. Therefore, it’s crucial to engage a methane testing firm with regional expertise to avoid project delays due to report rejections or revisions.

Second Step – Designing a Methane Mitigation Plan

Crafting a methane mitigation plan is the next phase for construction within a methane zone. This specialized design process usually necessitates the involvement and certification of a licensed geologist or engineer. The preparation of this plan requires a complete set of architectural and structural blueprints, along with a geotechnical report and grading plan. The geologist is responsible for developing a comprehensive methane mitigation plan, encompassing all necessary calculations and specifications for construction. For simpler projects, contractors may also refer to standard plans provided by the local building department.

Approval of the Methane Mitigation Plan
Methane mitigation plans also need to be approved before construction can start. Generally, the agency that reviews the methane test reports will examine these plans as well. Often, these two components are reviewed concurrently since mitigation plans are based on the site-specific methane test data.

Third Step – Constructing the Methane Mitigation System

Building an effective methane mitigation system in compliance with building codes and plans can be a complex task. It requires coordination with other site activities and timelines. This type of construction is specialized and mandates certifications from barrier manufacturers and approvals from various regulatory agencies.

Final Step – Inspection by a Qualified Methane System Inspector

In most jurisdictions, a certified “Methane Deputy Inspector” is required to oversee and validate the construction of the methane mitigation system. This inspector is responsible for ensuring that the construction meets the local building department’s standards. The deputy inspector, to avoid conflicts of interest, should not have any connection to the construction contractor. This inspection is a vital part of the methane mitigation process, marking the final checkpoint before project approval.

Methane Mitigation Construction by Arroyo Geo

Arroyo Geo’s approach to testing and mitigation design aligns strictly with LADBS standards, ensuring objectivity and compliance. For detailed information on methane testing, refer to Arroyo Geo’s article “Methane Mitigation Construction: Guidelines and Best Practices.”