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Geologic Hazards
Radon is a product of the radioactive decay of the uranium naturally found in abundance in Colorado. This gas can cause lung cancer and it is easily tested for. The UCCS Physics department is home to a Radon testing group that can provide instructions, materials, and testing to determine the level of Radon in your area (for a nominal charge of course). This is an especially important risk to consider for people in the market for a home. Mitigation can cost thousands of dollars in especially bad conditions. If the level exceeds 4 pCi/L then mitigation is needed. More information is available
here
. A Radon study conducted by the Colorado Geological Survey, in 1987-88,
and documented in Open File Report 91-4, found average levels in the Cheyenne Mountain/Fort Carson region (zip codes 80906, 80926, 80913
and 80904) exceeded the 4 pCi/L EPA standard. A more recent study was conducted by the UCCS Physics department in conjunction with the UCCS Geography department. That data was previously available and it is hoped that it can again be added to the UCCS Geography web site.
There is also a serious fire hazard not just from the physical effects to the forests, but also from the geologic effects. Fire causes heating of the outer layers of a rock. These layers expand and fracture the surface eventually falling off in a process known as spalling. This causes faster weathering of the surrounding rocks which increases the amount of gravel and sand that is washed into the watersheds on Cheyenne Mountain. This causes silting issues as well as posing a danger to fish in the creeks. In addition, any rock art or other archeological artifacts are usually destroyed from the spalling as well as the smoke and heat. Of special note is that faster erosion can lead to bank failures along streams that act as a dam. These dams hold up until they are overtopped by the water which then proceeds as a flash flood down the side of the mountain. A more dramatic example of this is the
Ferguson Rock Slide. With wild fires, you lose most ground cover which also causes a major erosion issue. The heat can bake clay like layers to the point that they are impervious to water, not unlike firing a piece of pottery for use as a cup. This creates burn scars that do not heal very well such as those in the Hayman burn area. They require special remediation work that is time consuming and expensive. There is also a major danger to homeowners, especially on the west side of Cheyenne Mountain off of Old Stage Road. There haven't been any major forest fires in this region for a while. This means we have a lot of standing dead timber as well as dead wood on the ground. Given the steep slopes, a fire in this area would be very difficult to fight if it could be fought at all. This is enough of a concern for the Cheyenne Propagation Company that they have been looking at ways to protect all of the antennae and buildings on top of the south peak. Bob Street, of Cheyenne Propagation, was kind enough to give me a tour of the antenna farm and he mentioned that they have been discussing this with the forest service. He said that they were looking into putting two large water tanks that would be filled from their well on the summit. The coordination
and approval process may prevent this from becoming a reality, however this is something that would go a long way towards making the antenna farm ?defensible? during a major fire. Property owners should also be concerned about evacuation routes in case of a fire. Old Stage Road is the only major road in the area and two way traffic with responding fire apparatus would find it difficult, if not impossible, to get by fleeing owners. Given the heavy fire load, this is an area that needs to have some extensive preplanning done between the forest service, private owners, and fire departments that would be responding. Those on the east side of the mountain are also at risk for forest fires. You can view the fire danger in your area at http://csfd.springsgov.com/Firewise/viewermap.aspx. From figure 4
and 5 you can see that the wildfire risk is high. An example is shown in table 1. Unfortunately many of these neighborhoods have only one way in or out. In the event of a major wildfire, they could find themselves cut off from escape and unable to move out of the path of the fire.
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Figure 4 |
Figure 5. |
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Wildfire
Risk Evaluation |
Table
1 |
| Address |
xxxx BUTTERMERE DR |
| Address/Lot Identification |
Address plate displayed and visible |
| Adjacency to Dangerous Topography |
Less than 30 feet |
| Roofing Material |
Not applicable |
| Siding Material |
Masonry, concrete, stucco |
| Defensible Space Around Structure |
20 to 30 feet |
| Vegetation Density |
Light density of conifers and/or brush
w/in 30 ft. |
| Overall Weighted Rating |
5.6 |
| Risk Category |
EXTREME |
| Last Rating Date |
August 19, 2005 |
Land slides are another geologic hazard to people living
and working in the Cheyenne Mountain region. The Broadmoor resides on the largest land slide on the entire Eastern flank of Cheyenne Mountain.
We also have to worry about coal mines in Colorado Springs. Many of these coal mines are located in the Rockrimmon area but there are still several that are in the vicinity of Cheyenne Mountain. The South Cheyenne Mine is one of those. It lies just south of the radio towers. I don't know if it lies within Cheyenne Mountain Air Force Station or not, but please don't go looking for it! Remember these mines are built using rough timbers that decay and weaken over time. Another mine on the Northeastern flank is the Heavy Stone Lode Mine which lies just north of the Penrose-Rosemont Reservoir and Gold Camp Road. The Johnny Mine is on the Southern flank of Cheyenne Mountain as well as the Menzer Quarry. Other mines are located further in town and are documented by Mr. Hoffman
here. The most important point to make is that you can buy life time coverage through the
Colorado Mine Subsidence Protection Program
for $105. With a $1,000 deductible, you are covered for up to $100,000. One family was saved the $70,000 cost to pump 280 tons of concrete grout into the mine tunnel below. The scary part for the crew that did this was that they had just drove their drilling rig, weighing about 2 tons, across that very spot a few hours before. The chasm was 12 feet wide and 16 feet deep! This program is supported through a federal coal reclamation tax to the tune of 2.3 million dollars a year. That doesn't go far when you have 23,000 abandoned mines in the state to worry about! Other instances a little farther from Cheyenne Mountain include a 5 foot deep hole in North Circle Drive, the Portal Park pool almost being eaten by a mine shaft, and another sink hole near Rockrimmon Elementary School. To prevent or minimize these soil issues, you can do a number of things. You can divert water around potential soil movements, shore up slopes with concrete retaining walls, build stronger foundations for new houses, and replace existing soils with soils less likely to swell and/or move. Another problem is that all coal contains radioactive particles so mine tunnels can fill with radon gas. Of course you will die from asphyxiation before the cancer gets you so don't go exploring. It is interesting to note that there is a ten fold increase in your radiation exposure standing
next to a coal burning power plant vs. a nuclear power plant. This comes from the radioactive minerals buried in with the coal.
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Figure 6. |
Figure 7. |
The steep slopes on Cheyenne Mountain are also at risk for flooding. The US Geological Survey (USGS) has a depth gauge on Rock Creek on the Southern Flank to warn of sudden changes in water levels. The first picture is of Rock Creek up on Cheyenne Mountain and the second is the gauging station on the southern flank of the mountain in the flat lands. Any gullies can concentrate the rainfall from hundreds of acres above and funnel it into the communities along Cheyenne Mountain. As there are not any long canyons we won't see any flooding like the Big Thompson Canyon flooding near Loveland but we might have enough to pick up enough debris to knock us off our feet or give us a few cuts and bruises. It is unknown if there are any reports of Fisher Canyon on the east flank flooding. The Colorado Springs Pre-Disaster Plan mentions a flash flood on July 24th, 1965 in which a landslide was triggered damaging the ape and hippo houses at the Cheyenne Mountain Zoo as well as dislodging boulders that crossed highway 115 and into Fort Carson. This caused tunnel blockages at NORAD and killed 4 people (pg. 23). There is also a report of over 9 inches of rain causing flooding and rock slides in Rock Creek Canyon on August 20th, 1980. This is probably the reason for the gauging station on Rock Creek. Lastly, on July 21st, 1985; approximately 5 inches of rain closed down Gold Camp and Old Stage roads as well as I-25. With both roads shut down, there would have been no way on or off Cheyenne Mountain.
These flood waters can actually cause a completely different sort of problem for us. Many of the soils around Cheyenne Mountain can absorb large amounts of water causing the ground to swell. This results in cracked foundations, upheaved driveways, broken fences, and in other situations actual ground movement up to an all out slide. The landslide-twisted home and buckled driveway of Ken Garrison in the Regency Drive area of the Cheyenne Mountain neighborhood. Surveying the damage are David Noe of the Colorado Geologic Survey (far left) and Mark Squire (middle), who administers the $4.1 million Federal Emergency Management Agency (FEMA) program that uses taxpayer money to buy out 23 landslide-damaged local homes
(Figure 8).
The foundation and twisted concrete floor of the Garrison's dream home on Regency Drive in the Broadmoor Bluffs area of Cheyenne Mountain. The four-level structure was so close to collapse that it was razed after
condemnation (Figure 9).
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Figure 8. Photo courtesy of David Noe |
Figure 9. Photo by
Meggen Burghardt |
Some examples of this serious problem: the previously mentioned 1965 flood and rockslide at the Cheyenne Mountain Zoo and temporarily closed
CMAFS.
In May of 1995, Ken and Ann Garrison of 4270 Regency Drive woke to a shudder running through the house. Two weeks later they had a foot wide gap in the house with a 3 foot wide by 7 feet deep hole in the backyard. Seven weeks later it was condemned resulting in a total loss for the Garrisons. No one told them that their house was built on the site of a land slide. This brings up a very important point: your house insurance does NOT cover damages from moving soils or other earth movements as the Garrison's discovered. This event became the driving force behind a request to declare the area a disaster area, a request the president signed. As no funds were available, congress gave the Federal Emergency Management Agency (FEMA) a special fund of 6.4 million dollars to buy out 23 homes. 230 million dollars came from the HUD budget since congress felt it was a housing issue. This means that, on average, each homeowner received over $178,000 which was to cover 75% of the cost with the remaining 25% paid by the owner. The lots were not allowed to built upon again as a condition for the federal aid. If this condition was violated on even 1 lot, then Colorado Springs would be liable for repayment of the entire grant. In the Garrison's case, the developer settled out of court for a confidential amount, the house was razed,
and they moved out of state.
In 1999 in the Broadmoor Bluffs neighborhood, one of eight identified as at risk, 35 more houses that suffered land movement and soil expansion damages were bought out under a similar situation with damages of 80 million dollars. We had over 17.5 inches of rain that month and the total rainfall for the year was over 37 inches.
This isn't widely discussed as people do not want to hurt their home's value and in most cases aren't aware of the problem. City Council has been ineffective in dealing with the developers. The developers have complained that the Colorado Geological Survey (CGS) staff are overly critical and have asked for different oversight on their development plans. Some have even told the council that they can only check if the information is available to the public. The driving force is that each lot that can't be built on can cost the developer hundreds of thousands of dollars. These developers have kept the council in check by threatening lawsuits if the city doesn't sign off on the plans as in the Pinecliff development proposal. Jack Wiepking stated that the ?Regency Ridge Landslide Disaster was an isolated incident? which has been shown to be false by the number of events. His feeling is that the city doesn't have the right to tell them they can't build on unstable slopes. The legal interpretation they hold is that a denial to allow construction is the same as the city ?taking? private property. Many developers have also claimed to have no knowledge of any geologic hazards in Colorado Springs. Even city employees have been called in to testify in lawsuits such as the Garrison's that they were unaware of any hazards or documents that discussed those hazards. This prompted a CGS report, Map Series 42, in 2003 entitled Map of Potential Areas of Landslide Susceptibility in Colorado Springs, El Paso County, Colorado. In this report they identify reports as far back as 1973 that discuss landslide hazards. They also show damage to the Broadmoor golf course from 1996. This ongoing problem of land movement damaging the golf course forced a redesign of the golf course which was a reason for their selection to host the 2008 Senior PGA Open.
This report also identifies suspect geologic formations such as the Pierre Shale that have high clay content and can become active when water is added to them. This is typically seen when a new house is built and fresh sod is laid down. All of that runoff finds its way into the soils causing damage to the house. There are numerous building techniques that can be applied, but they are more expensive than traditional home construction.
It is estimated by the Colorado Geological Survey that up to 5,000 homes may be at risk. It is important to note that many of those 5,000 homes are valued above half a million dollars EACH. It is estimated that 75 million dollars in damages from earth movements were caused by events in 1995 and 1998. The federal funding is only available during certain periods and an owner can find themselves with a half million dollar chunk of worthless ground if they aren't careful. Should we be bailing these owners out or should we tighten up on development proposals and hold the builder liable for the loss? In any case, there is a very slim chance that everyone will be happy. One other interesting concern was identified. What if a house in a neighborhood caught fire and thousands of gallons of water were applied to put out the fire. The neighbors would obviously want the fire stopped before it spread to their houses. Now imagine a few weeks later finding foundations buckling and slopes sloughing. Millions of dollars in damages could be done. So the question is ?would the city have responsibility for the damages caused by the fire department's use of water to put the fire out? What happens if rescue personnel are forced to attempt rescues in these unstable houses and they are injured or fire equipment is damaged by sliding material? Who is liable for a house that is built on an unstable slope and collapses injuring or possibly even killing someone? Is that reckless endangerment of the public? These are difficult questions without easy answers.
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