L.I.P. Bulletin, Volume 4, Spring 2010 Page: 2
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Large rocks were
used to establish a more
stable trench and sinkhole edges.
A team of volunteers and a landscape architect/caver worked
extensively to develop a plan. Work began in spring 2003 and
spanned multiple years, involving support from numerous volunteers
as well as a USFWS Partners Grant, a Kronkosky Grant, a Wrey Grant -
Magnolia Foundation in addition to the LIP grant.
A large portion of time and energy was dedicated to the removal of the
I that had been dumped in the cave in the 1960s and '70s, and the
toration crews were relieved to find the fill was relatively clean with no
t, chemicals, or significant pollutants. By summer 2004, an estimated
cubic meters were removed from the sinkhole, and its depth increased
.5 m. to 9.2 m.
lately after the completion of the excavation, wildlife habitat-friendly gates
alled. Both gates allow maximum airflow, water entrance, and passage of
d small animals.
With proper gates in place and dumped materials removed, restoration crews began addressing the considerable erosion and
runoff contamination problems. Because of the threat of pollution from the major street on the east side of the property, a low
retaining wall was created along the street. This retaining wall deflects the first wash of pollution off the street in a major rain event.
The next efforts to solve the erosion problem were focused on the edges of the trench. Large boulders were placed on a
secondary ledge with native plants, sand, and dirt interspersed to stabilize the area.
Next, field stone, gravel, and mortar were used to build a retaining wall at the bottom of the sinkhole, restricting the dirt that
remains in that area. Then, using the same materials, steps were built in the trench. Behind each step, gravel was used on each
level to act as a filter for the water as it comes down the trench. Short lengths of PVC pipe to act as weep holes were placed at
the base of each step to control drainage through the gravel and the step.
At ground level, exotic vegetation (ligustrum, Boston ivy, etc.) was aggressively removed. Directly around the sinkhole, some of
the non-native plants were left to stabilize the area, and gradually those will be replaced with native plants.
Gravel paths, retained by metal edging, were laid along the property. A new layer of topsoil was distributed on the lot for final
planting. Several phases of plantings and mulching have established beds of native, drought-tolerant plants and shrubs. The
primary purpose of these plantings is to prevent erosion. This final effort served both to aid in erosion control as well as to
maintain the types of plants which might be expected to be around caves in this area, and to develop an aesthetically pleasant
area in the residential neighborhood, encouraging pride and ownership. The grounds of the property are open, but the cave is
not open for unsupervised visitation. An educational kiosk was placed at the top of the trench that goes down into the sinkhole
of the cave. Additional cautionary signs are placed to warn of the dangers inherent in a cave sinkhole.
Work is ongoing at this cave property, but the effects of the changes already made have already been noted. The improvements to
the property have resulted in positive comments by many people in the neighborhood and seem to have increased the respect
people have for the property. Dumping of trash on the surface and in the sinkhole has nearly ceased, and vandalism incidents
have become rare and minor. In the cave, more than a half-dozen Robber Baron Cave Mesh Weavers have been spotted byTCMA
members over the last year. One was seen spinning a web in an infrequently traveled passage. In 2006, visitors found a bat on
the ceiling of the entrance passage. This was the first sighting of a bat in Robber Baron Cave in decades. Since then, the number
has increased each year with 10 bats observed in the cave at the end of 2009. The cave biota is thriving as the cave entrance
and the grounds are restored to natural conditions. With TCMA serving as the steward to this special property, and with the
support of organizations like Texas Parks and Wildlife, the natural environment of the cave can be restored and preserved.
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Texas. Parks and Wildlife Department. L.I.P. Bulletin, Volume 4, Spring 2010, periodical, Spring 2010; Austin, Texas. (texashistory.unt.edu/ark:/67531/metapth576238/m1/2/: accessed August 15, 2018), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; crediting UNT Libraries Government Documents Department.