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Contact Us: 909/867.3536
Email: [email protected]

San Bernardino Mountains Land Trust
Nonprofit Organization 501(C)(3)
Tax ID # 33-0700417                                                                                                                                                                                                                                                                                                                                                                                                                                                       


Volunteers Assist in Major SBMLT Project

Bat Gate Constructed at Mine Entrance


  Welder John Norman completes a steel bat gate enclosure


As a pre-condition of the sale to the Forest Service of the Yaeger Mesa parcel, the San Bernardino Mountains Land Trust agreed to construct so-called “bat-friendly” gates at both outlets of the 100-year-old mine that runs through the mountain.  The narrow tunnel extends about 2,000 feet from end to end.

Bat gates are intended to protect unique cave habitat and reduce liability of potential hazards.  They are locked except for authorized entrance and special circumstances.  The project posed a huge challenge, because the mine was 1.5 miles from the trail head and up a steep overgrown canyon.  Over two thousand pounds of materials and equipment had to be hauled up by hand.


  Boy Scouts and parents at the entrance of the Yaeger Mine

The Land Trust was able to enlist the expert assistance of the Southern California Grotto, an organization of highly experienced caving enthusiasts.

The project required extensive planning with many trips to the mine to take measurements, trim back poison oak and attach climbing ropes for scaling two steep cliffs in the narrow canyon.  Each expedition also included a recreational tour through the colorful intriguing mine.

After ordering all the materials, which included 1,600 pounds of steel angle bars, an entire weekend was set aside to transport everything to the site and construct the first bat gate.  Heavy welding equipment, generators and bags of cement were hoisted up the canyon by hand.


Caver Marc Heins conducts tour of the mine tunnel


Forty volunteers participated, including about 15 Boy Scouts and leaders.  Eight-foot lengths of angle iron were brought up one by one, each on the shoulders of two hearty backcountry strongmen.  The Boy Scouts and two of their mothers helped carry up cement in 20-pound bags in backpacks.  Everyone got a tour of the mine.

Construction was started late on the first day and completed near the end of the second day.  The welding team consisted of experienced members of the spelunking group.  The steel gate was built to professional specifications provided by the Forest Service.  Two weeks later the second smaller entrance, where a tiny stream flowed from the mine, was enclosed with a stainless steel culvert and gate.  Each project was inspected by a Forest Service official.


Yaeger Mine - Bat Gate Construction Project





Taking measurements and drafting preliminary plans for a bat gate at the upper mine entrance, which is the larger of two adits on the property and the more difficult one to access.













Unloading steel components for the bat gate.  The 16 pieces of partly fabricated metal (with a combined weight of 1,000 lbs) all need to be carried by hand to the mine entrance for the onsite construction.


















Marc Heins views the mine before the bat gate is installed.
















Kevin Kellems and Marc Heins carry the sill plate, the heaviest piece (at 75 lbs) of all the steel components, transporting it uphill 1.25 miles to mine entrance.









Bringing up cement and tools in heavy backpacks.










Volunteers unload steel to carry up the the mine.










John Norman and Scott Schmitz lead over 30 volunteers who help transport all construction materials, generators and welding equipment up to the mine entrance.







Steep cliff in the ravine, where two ladders and a rope had to be positioned so volunteers could hoist up all the heavy materials and equipment.








Setting up welding equipment.











Measuring steel bars for cutting.















Digging footing for the gate.













Drilling into rock.









Project Leaders James and Alan Rice.














Making final welds for lock bolts.











Inscribed date and "SCG" (for Southern California Grotto).





Bat Gate design and detail of removable bar.





Water for cement came from a steady drip in the cave wall.









Mine tunnel.









Groups of Boy Scouts were given tours of the mine.  Each boy carried 20 lbs or more of cement to the project site.














Finished Bat Gate