Environmental Engineering and Contracting

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

Office: 818-967-5977
Cell: 818-326-3200

A-HAZ Engineering Contractor Lic. No. 1062092

Frequently Asked Questions

For on-grade buildings, the rough cost of installation of a vapor barrier system typically falls in range if $7 to $12 per square foot of area, depending on the application. For larger buildings that require shoring and underground parking levels, the per-square-foot cost increases since both the subslab and shoring walls needs to have spray-applied membrane. For this reason, methane tests are required by regulatory agencies for properties in areas of former landfills, oil fields and oil wells, or swamp and marsh areas.

The answer is yes for most cases. In many cases, the building departments make little to no changes to an initial methane mitigation plan submittal, especially for passive mitigation systems; in which case a tentative bid can be prepared and then finalized when the plan is approved.

In some cases, when the methane mitigation plan is completed, involves an active mitigation components such as gas extraction and ventilation and alarms, the plans need to be reviewed by several other departments in addition to plan check (plumbing, fire dept, mechanical) and in these cases it is best to wait until final approval is achieved before asking a contractor to provide a bid for installation.

Methane is a flammable gas that exists in the subsurface, due either to natural or man-made causes, and can cause explosions if the concentration of the gas reaches beyond a threshold for a confined area.

For this reason, methane tests are required by regulatory agencies for properties in areas of former landfills, oil fields and oil wells, or swamp and marsh areas.
Agencies will vary in their requirements, but since a methane test indicating no methane concentration does not necessarily mean methane cannot collect in the subsurface in the future, most agencies require some form of passive mitigation system to be designed and installed as part of a new construction project for properties in the Methane Zone.

A passive methane mitigation system consists primarily of a sub-slab vapor mitigation system, consisting mainly of pipe and gravel under the slab and membrane, followed by installation of a methane membrane that typically gets installed under a concrete slab.
Yes indeed, Arroyo specializes in this service. Together with our affiliate consulting company Applied Earth Sciences, we assess over 100 properties every year for commercial, residential, and public works clients.
Typically the environmental contractor works closely with the environmental consultant to determine the best and most efficient remediation method to remediate an environmental site condition.

One of the primary advantages of working with Arroyo is that we work closely with our affiliate earth science consulting firm AES, and share resources with this company, and hence have access to all manner of techniques, such as soil hauling, hazardous waste removal, in-situ carbon adsorption, groundwater pump and treat, air sparging, soil vapor extraction, and much more.
Typically, a fee estimate for an investigation and report will include all of the work involved in preparing a comprehensive report, including drilling cost, lab fees, and other overhead cost. However, some of the services not typically included in a fee estimate are supplemental work as a result of changes to project plans, or responses to correspondence letters from regulatory agencies requiring additional work.

These fees are calculated on a time and material basis. Also, review and signature of a civil or structural engineer’s plans is typically a separate service provided at a much later time, since projects can change hands multiple times before a building is actually constructed; and as such is billed separately from the preliminary cost estimate.

Lastly, inspection services are not included in a preliminary cost estimate. Even a rough cost estimate for inspection services during construction requires approved detailed plans, and then can still be subject to change, depending on several factors such as contractor’s level of experience, complications arising onsite resulting in delays, etc.
We perform several dozen methane field tests every year. Trapped and concentrated methane gas in a subterranean garage can result in large explosions and present a severe safety risk. As such, “Methane Zones” are designated by cities and counties where there were formerly oil fields, tar pits, landfills, or swamps.

Industry professionals who are experienced in methane are required to test each site prior to proposed improvements being approved and permitted. If methane is detected, an active methane mitigation plan is required. Even in some cases where methane is not detected, a so-called “passive mitigation plan” is still required. At Arroyo we specialize in the preparation of methane mitigation plans for all Site Design Levels.

Various regulatory agencies have different requirements for these plans, and our design team is experienced with the various requirements of several municipal agencies across southern California where methane gas is a known hazard, including the city of Los Angeles, county of Los Angeles, the cities of Long Beach, Fullerton, Ventura, and elsewhere.

Please submit the plans to Arroyo Geo at info@arroyogeo.com, with a brief explanation of the project. One of our specialists will get back to you shortly.

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At Arroyo/AES we typically follow site testing standards for methane testing issued by the LADBS, but other jurisdictions have other requirements. Most typically, at least two boreholes are drilled into the ground, either by direct-push, land labor, or hollow stem auger.

In each borehole, nested monitoring wells are installed at various depths below ground surface, and the methane concentrations are taken for at least two days. A brief report follows, with the results of the testing and further recommendations.
Arroyo Geo, an A-HAZ engineering contracting company with experience, knowledge and know-how in methane mitigation systems, can install methane/vapor mitigation systems for new construction projects.

Our interdisciplinary team of engineers, scientists, and field labor/supervision teams offer unmatched excellence in this specialized line of work, especially for complicated projects that require frequent real-time adjustments and correspondence with other design professionals and subcontractors.

It should be noted that, consulting companies are not authorized to install mitigation systems, nor are contractors whose main experiences lie in other trades.
These are known as Recognized Environmental Conditions, and typically warrant some sort of intrusive environmental investigation of the site to determine if the subsurface has been impacted.

Typical RECs are encountered on sites affected by prior/existing gasoline stations or laundromat operations, auto repair facilities, and defense/airline manufacturing facilities. It should be noted that, consulting companies are not authorized to install mitigation systems, nor are contractors whose main experiences lie in other trades.
Geologists and engineers are like two sides of the same coin, although they take decidedly different academic paths. Geologists typically direct the earlier site characterization phases, while engineers are more involved in the later design phases.

This is true whether one considers the petroleum, mining, geotechnical, or environmental industries. Included as a part of geotechnical services, geologists and soils engineers typically produce one jointly written report, with a geology section and an engineering section. Some more specialized firms produce stand-alone reports that are submitted in conjunction to regulatory agencies instead.

Geotechnical projects in flatland areas do not need the services of a geologist, while a fault hazard report or an environmental site characterization need not have an engineer’s signature.
As providers of services, and not products, a geoscience professional’s fees are based on the time he estimates to complete a scope of work, as well as the cost of materials involved.

This is typically called Time and Materials. The main differences, then, in fees, are the hourly rate, and the productivity of the engineer. Arroyo Geoscience strives to perform high-quality consultation at very competitive rates and fees.
In addition to methane tests and mitigation plans, we perform environmental site assessments to ASTM Standard 1527-05, phase II site characterizations, groundwater monitoring and water quality testing for SWPPP; percolation testing for onsite wastewater disposal systems (OWTS); and field percolation testing for stormwater infiltration best management practice (BMP).

With regards to engineering-geologic services, we provide geologic site characterization for geotechnical engineering projects, downhole geologic logging, deputy grading and methane inspections, landslide investigations, aerial photo interpretation, fault studies, and prior-to-purchase investigative services. Call or email us for details.

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