Digging The Outdoors

By Mike Harrison

At The Irvine Ranch Outdoor Education Center in Orange County, Calif., kids are digging into environmental science--below ground.

The center leads the way with programs in which children living in a primarily urban environment experience both traditional camp activities and hands-on outdoor academic programs. These activities give them an appreciation for the natural environment while teaching them about the cultural history of the region and the science behind aerospace, astronomy, engineering, mineral science, geology, hydrology, water and natural-resource conservation, plant biology, agricultural science and nature’s interdependence.

Owned and operated by the Orange County Council Boy Scouts of America, the center is located on 210 acres donated by The Irvine Company. It also serves the Girl Scouts, YMCA groups, school outdoor education programs and many other community youth organizations.

One unique element of the center is the Lucy-Lou Mine. It provides experiences that teach the area’s mining history, mineral science, geology and engineering. In the mine, kids get to dig in the dimly lit branch mine shafts, wearing lights on their miners’ hard hats.

Constructing History
Completed in August 2008, the 1,900-square-foot mine was built using concrete tilt-up wall panels and a poured-in-place concrete ceiling. Four hundred cubic yards of concrete and 40 tons of reinforced steel were used in the construction. In some areas, the mine shaft walls are 18 inches thick. The ceiling varies in thickness from 12 to 24 inches. The wall panels were poured on uneven ground with native rocks and simulated geologic formations cast into the surfaces. After the walls were raised and set in place by a large crane, scaffolding was set to support foam blocks covered with dirt to form the ceiling. After the ceiling was poured and the scaffolding removed, the dirt that was still stuck to the ceiling was chiseled, leaving the impression that the chiseling was what excavated the mine. The concrete walls at the entries into the hillside are covered with old-form lumber that gives a shored-timber appearance. The lumber extends above-grade to form a required guardrail around the opening. The stairwell entry and bucket-hoist shaft from the upper level have the same lining. The mine is in a rough horseshoe shape with an entry point into the hillside at each end. Branch shafts and the stairwell are located at the midpoint.

The mine’s two branch shafts are named for the historic mining areas in Orange County--the Blackstar and the Silverado. Both shafts can be loaded with material from the upper level through hatches in the ceiling. The Blackstar shaft features a coal formation formed by combining cement with low-grade lignite coal from a historic spoils pile about two miles from the site. The mixture is non-combustible by fire department standards, and doesn’t create fine dust when chipped out by miners. The mixture is placed in layers in the Blackstar shaft where it can be mined along with other materials buried by staff in the surrounding dirt. The Silverado shaft is similarly salted with various minerals, rock types, geodes and other interesting finds.

The Big Dig
After a mine-safety lecture--which includes warnings about the dangers of exploring abandoned mines, and adjusting hard hats and lights--the miners descend into the mine with trenching shovels and geology picks. Under staff guidance, they dig out materials mixed with the native dirt from inside the branch shafts into 5-gallon pails. The pails are dumped into a chute that runs through a rebar grate into a mine hoist bucket running on a garage-door track vertically inside a 4-foot-square rebar cage to the top of the hoist mechanism. The hoist is powered by a hand-cranked, boat-trailer winch mounted in a lockable box at the upper level. A hook engages the hoist-bucket lip, and the contents are dumped down an upper-level chute as the bucket moves over the curved portion at the top of the track. The chute exits the stairwell enclosure through a 3-foot x 3-foot door, where the contents come out onto a sorting table. The winch operator stands next to the open door where the bucket can be watched from the bottom to the top of its run. After retrieving the interesting materials, the remaining dirt is pushed through a hatch in the table into a 2/3-scale ore car below. The ore car can then be pushed 140 feet on a level track where the “tailings” can be dumped over the edge of the bank onto the tailings pile. Eventually, the tailings pile will be recycled into the branch shafts through the ceiling hatches.

"The mining operation is one of the most exciting and memorable elements of our program," says Christine Kirk, outdoor education director of the center. “The kids going through our mine programs think that the mine is one of the coolest things they have ever experienced,” she adds. “This, of course, makes us smile, but what makes it even better is that we know they will remember what they have learned for much longer than if they had studied it from a book. The mine provides the type of personal experience that stays with learners as all their senses are involved. Our mine programs teach children about their world below the ground--geology, mineral science, soil horizons, plate tectonics and other aspects of Earth Science. The children also learn something about mines, local history and the mechanics of gear ratios and pulley systems.”

Replication And Recognition
“For many of the kids who go through our programs, it is their first time exploring the natural environment around them in hands-on academic ways,” says Kirk. “When they arrive, they don’t necessarily have an understanding of or an appreciation for where the materials used in their electronics, automobiles and buildings, or even in jewelry come from. We work to help them understand the historical and economic place that mining holds in our world, as well as some safety and environmental issues.”

If mining is part of the history of the area where your camp is located, building a simulated mine may add exciting dimensions to programming. It is possible to build a smaller, less elaborate and less expensive version of the Lucy-Lou using the same construction techniques.

“There are other mine shafts that we know of at camps around the country,” Kirk says. “We were thrilled that ours won the 2009 Tilt-Up Concrete Association Achievement Award in the Special Projects Division, recognizing its realism and safety.”

Cost And Space Considerations
The mine has a floor area of about 2,000 square feet, but the area inside the perimeter of the horseshoe shape is closer to 15,000 square feet, with allowance for the surrounding slopes laid back during construction, and a stockpile area of the dirt excavated and later re-compacted around the walls and over the ceiling. As a part of grading for other purposes on the site, an activity pavilion and 13- x 13-foot bucket-hoist house were created, as well as a stairwell structure that is 13 feet above the two lower-level entries to the mine. There is a 2-to-1 sloped bank between the lower and upper levels. The ceiling level in the mine varies from 7 feet 6 inches to 9 feet, and the floor slopes at 2 percent from the stairwell to the lower level entries. The dirt cover over the concrete ceilings varies from 2 feet to 4 feet.

The cost of design and construction was approximately $400,000, or roughly $200 per square foot. While the cost was not cheap, the project excited the imagination of both program staff and financial supporters enough to raise the money to cover the costs.

Simply Magnetic
The Mining Camp at The Irvine Ranch Outdoor Education Center is magnetic--kids are mesmerized by what they find and learn during their digs. Together with the Center’s Aerospace & Astronomy Camp and Ranch Camp elements, the simulated mine brings learning about the area’s natural resources and history to life in an exciting and safe environment.

Mike Harrison of Corona del Mar, Calif., is president of Mike Harrison Construction and Vice President of Trico Realty, Inc. He is an avid supporter of The Irvine Ranch Outdoor Education Center, having participated in its conception, planning, construction and fundraising efforts. He can be reached via e-mail at mike@tricorealty.com.