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Frontier Environmental Solutions

Frontier specializes in remote site construction. Our area of expertise is designing and installing bat friendly gates.

As humans encroach on their natural habitat, bats have taken refuge in caves and abandoned mines. But even there, humans will trespass for recreation or just vandalism. These gates are designed to exclude humans and present the smallest impediment to bats and the natural air flow of the habitat.

Bat compatible gates

Foam Closures

Years of Experience

Gate Design

Gates are designed around the threat to the particular habitat. Click on each picture for additional details.

  • All
  • Standard Adit Gates
  • Shaft Gates
  • High Security Gates
  • View-Shed Friendly Gates
  • Gates in Concrete Structures
  • Air Vents
  • Foam Closures
  • Special Projects
  • Videos
Standard Adit Gates

Standard Adit Gates - Typical

Typical Bat Conservation International/American Cave Conservation Association bate gate

Typical Bat Conservation International/American Cave Conservation Association bate gate installed in adits of any shape.

Standard Adit Gates

Standard Adit Gates - Unstable site

Adit gate on an unstable, fine grained powder site.

This site consisted of unstable, fine grained powder. Anchoring a gate to this would be impossible. The solution was to install a six-foot concrete culvert in the opening and build a standard gate inside it.

Shaft Gates

Shaft Gates - concrete bars

Cupola bat gate installed over a shaft.

Cupola bat gate installed over a shaft.

This particular site is a high vandalism-threat area so the bars are filled with concrete.

Shaft Gates

Shaft Gates

Cupola gate installed over a six foot diameter shaft.

Cupola gate installed over a six foot diameter shaft.

High Security Gates

High Security Gates

Plug style bat gate

Plug style bat gate used in high vandalism-threat areas or where the soil conditions require concrete reinforcement.

View-Shed Friendly Gates

View-Shed Friendly Gates

"Stealth" gate designed to minimize straight lines observable from certain directions.

"Stealth" gate designed to minimize straight lines observable from certain directions. This makes the gate virtually invisible to the public or vandals throughout a given viewing area.

Gates in Concrete Structure

Gates in Concrete Structures

Bat gates can be installed in concrete structures such as this wine cave.

Bat gates can be installed in concrete structures such as this wine cave. This structure was designed to allow free access for bats while preserving the historic nature of the opening and existing wooden door.

Air Vents

Air Vents

Covering a shaft that has no bat population.

This is one way to cover a shaft that has no bat population but is part of an underground working that supports bats elsewhere. It maintains air flow patterns and thus the existing environment for transient or hibernating bats. This structure was designed to withstand a 5000 lb vehicle either driving on it or attacking it.

Foam Closures

Foam Closures

A foam closure of a mine with no bat populations.

This is a mine with no bat populations. It has injured several explorers and has an unsafe oxygen level. The Forest service decided to have us close it.

This polyurethane foam (PUF for short) is a sturdy way to close the shaft. The vent pipe is used to retain some of the airflow for other connected underground workings. This closure required carrying 165, twenty-five pound packs of foam for one-quarter mile.

The foam will deteriorate in direct sunlight. A foot of dirt as cover prevents the UV light from damaging the foam and hides its presence from vandals.

Special Projects

Special Projects

This headframe was a favorite landmark of the area, featured in several movies from 1930 through 1990.

This headframe was a favorite landmark of the area. It had been featured in several movies from 1930 through 1990. It was manifestly unsafe but was required to remain on site. The workings around the opening were extremely dangerous but were required to be maintained as is. Additionally, multiple bat sightings required a bat friendly structure.

The old headframe was removed and a bat gate was installed on a new concrete foundation. The structure enclosed all the historic workings and covered the safety hazards.

A new headframe was designed using steel I-beams covered with wood. The wood was held in place using steel bands to retain the original appearance. All external dimensions match the original and in a few years, the new wood will weather to the original color.

Benchmark 19 Mine

Benchmark 19 Mine

Dirty Jobs

Dirty Jobs


Frontier is about service and satisfaction. You have a vision or a concept and we implement it. We have 21 years of experience closing hundreds of mines. When others companies tell you about a single project they completed, we can tell you about hundreds we have completed. Experience is invaluable. Let us handle your project and you will be more than pleased with the results. We have worked with almost every government agency and a lot of private land owners to help them reduce their exposure to liability while being responsible stewards to the wildlife using abandoned mines as habitat.

Our track record means we have done work in almost every situation. Whether the site requires boats, mules, wagons or a helicopter to mobilize, we have done it. Each site presents a different set of challenges. Our experience makes those challenges manageable. We minimize risk, we have a verifiable safety record and we have an excellent track record. When you want to complete a project, you have an easy decision. Why choose an unqualified company with no track record when you can have experience and quality?

Our services basically fall into three categories:


Our consultation services leverage on our construction experience. Your biologist may have extensive experience with wildlife surveys, but they likely have no experience building the desired structures or implementing closure plans. Once you have the biological data, let us help you develop a plan to protect your property. A comprehensive plan requires data and experience. If you provide the data, we can provide the experience. If you need help gathering the data, we can refer you to resources that can provide assistance. Whether it is for compliance documentation or wildlife surveys, we can refer you to the right group to get the job done. Once you have the right team assembled, your project will run smoother and the outcome will be a responsible mix of the appropriate techniques to protect wildlife, the public and your liability. Resources are stretched to the limit in today’s environment, not just financial resources, but human resources as well. There is a distinct shortage of qualified, experienced personnel within agencies that are needed to get your project from concept into action. Frontier can help.


Our construction services are the product of our experience. When it comes to implementing a closure plan, whether it is for a single opening or thirty of them, we are your best choice. While we cannot guarantee the structure forever, we can assure you the structures we build for you will be built to blunt the enthusiasm of the average vandal. Too many times we have been brought in to replace a structure that was not built to standards. Choosing a contractor with no track record or an inferior design will likely produce less than desired results. Quality does not mean exorbitant prices, it means value. Call or email us today to get started with your project.

Land Management

The third side of our business focuses on helping our existing land manager clients. These clients trust us to make them more productive by handling some of the most time consuming aspects of land management, periodic property checks. Whether it is monthly, quarterly or yearly, we can often accomplish these property checks for our clients for a reasonable price. Most companies require their land mangers verify the condition of their properties on an ongoing basis. While these site visits are sometimes low priorities, they can be extremely important. Work with Frontier to accomplish these site visits and know your company’s property is in a known condition to protect the company as well as repair any damage or vandalism quickly to show diligence. It allows the land manager to get more accomplished which benefits the company.



Frontier has no biologists on staff. We consult with Bat Conservation International and established expert bat biologists before installing any gate.


  • Licensed Professional Engineer
  • California State Contractors License #927479:
    General (A), Electrical (C10) and HAZ (Hazardous Substance Removal)
  • California Waste Tire Hauler TPID: 1950463
  • Nevada State Contractors License #0089286:
    A General Engineering
  • MSHA Mine Safety Instructor
  • Commercial Helicopter Pilot


  • Bat Conservation International course on design of bat gates
  • MSHA surface and underground qualified
  • OSHA certified gas tester
  • CPR training
  • Horse and mule wrangler


  • More than 1300 bat compatible gates in adits and over shafts
  • More than 320 Foam Closures in abandoned mines
  • Bat gates installed from Michigan to the Mojave Desert and Catalina Island

Find Out More About Us

Although we never thought it could grow into the enterprise it is now, we focused on how to do the work safely. Our initial work focused on bat compatible closures. As we completed more and more closures, we discovered a growing need for the work we were doing and our business continued to expand.

  • Frontier was founded in 1995 in response to a need.

  • In 2000 we added polyurethane foam closures to our business.

  • Over the last decade, our construction and consultation work has expanded from our base area of the desert southwest to jobs across the country.

  • The staff of Frontier has a diverse background

    In addition to 21 years of experience closing hundreds and hundreds of mines, we have years of experience as engineers, pilots and project managers.

lf you are interested in a mine closure, you can rest assured your project will be handled with skill and completed to your satisfaction. We have excellent references. Our customers are federal (Forest Service, Park Service, BLM), State (Fish and wildlife), military, and private landowners. Many of them have asked us back for repeat work when new openings were discovered. Our design packages fully describe the project and pictorially show the finished gate. Frontier is a small business registered with Dun and Bradstreet and the U.S. Government Central Contractor Registration.

Forest Service
Park Service
Bureau of Land Management
California Department of Fish and Wildlife


There are currently no open positions.

Contact Us

Mailing address

Frontier Environmental Solutions, Inc.
P.O. Box 911
Inyokern, CA 93527

Call Us

(760) 608-1869

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