Tuesday, June 7, 2005 | 8:35 a.m.
A Henderson consultant said construction blasting did not crack walls in homes at MacDonald Highlands, Crystal Ridge and Sun City MacDonald Ranch.
Wind and temperature and humidity fluctuations are more likely to blame for the damage, the consultant said.
The release of the report comes as criticism continues to mount over developers blasting away rock to clear sites for home construction. Lake Las Vegas residents are the latest group to join the fray by opposing blasting proposed near their homes.
Blasting contractors and developers used the report to validate their claims that they are not causing any damage. Some Henderson residents with damaged homes, however, remained skeptical and asked for further proof.
In her report to the city, Catherine T. Aimone-Martin, a professor of mining and civil engineering at New Mexico Institute of Mining and Technology, said instruments were used to measure ground vibrations and air movements from blasting in Sun City MacDonald Ranch and MacDonald Highlands. Other gauges measured movement of pre-existing stucco exterior wall cracks during blasting, construction and high winds.
In her conclusion, Aimone-Martin said there is a 100 percent probability that blasting under the existing city regulations hasn't caused the cracking. Structure motions and wall strains produced by wind gusts of 31 to 34 mph were 10 percent greater than those produced by blasting, and large variations in temperature and humidity produce wall strains 72 times greater than the blasting, she said.
Aimone-Martin wrote that "large weather-induced changes in crack width is the greatest contributing factor to crack extension and widening over time. The influence of wind pressures against walls during a typical storm produced crack width changes greater than those produced by blasting."
The report was immediately challenged by Glenn Christenson, a MacDonald Highlands resident who had led the charge against blasting near homes. Christenson said Aimone-Martin has a bias because she has never seen any blasting-related cracking in her career.
Christenson said he plans to extensively question Aimone-Martin when she discusses her study with homeowners. He has rejected arguments weather has caused the damage because the cracks didn't occur until the blasting started.
"It is just not plausible that this damage is a coincidence," Christenson said. "We are never going to agree on the level of damage caused by developers. My focus is going forward. How is the city going to protect the residents from developers? The developers have had open season in Henderson, and now we are looking to the City Council to protect the residents."
Henderson officials said protecting residents has been the No. 1 goal, and the reason they hired a consultant and on March 24 put a moratorium in effect on close-range blasting near homes. On April 27, a District Court judge ruled against the city and in favor of Foothill Partners, the developer of MacDonald Highlands, resulting in Henderson ultimately allowing the blasting within 300 feet of homes.
Mayor Jim Gibson said Monday that the city may need to hire another consultant to get more information and lend more credibility to what may have caused the damage to homes. He also said it remains a priority for the city to consider changes to its blasting ordinance this summer.
"We want to do the right thing and not do anything that would cause a proliferation of damage," Gibson said.
Foothill Partners, relying on its public relations firm, immediately cited the report as vindication that the company isn't responsible for any damage. The type of cracks found at homes in MacDonald Highlands have been reported throughout the Las Vegas Valley, including areas several miles away from construction sites, said Mark Fierro, a spokesman for Foothill Partners.
Fierro cited National Weather Service data calling February the ninth wettest month in the valley's history and 2004 as the fourth wettest year in history.
"This is precisely what we have been saying all along," Fierro said. "The real stressors in this valley are record rainfall, high winds and the dramatic changes in temperature we've seen. We are not responsible for damage to any homes at any level."
Blasting contractors have defended their practices and said the city's code is so conservative that no damage could result from explosions using ammonia nitrate. Henderson's code allows 0.5 inches of vibration per second, the lowest in the region, they said.
"It is just what we expected," said Dave Donner, the owner of Donner Drilling & Blasting, which is blasting in MacDonald Highlands. "I am not surprised by the fact that the wind and the temperature changes are causing damage."
Donner said he's awaiting city approval to resume unrestricted close-range blasting in MacDonald Highlands following a May 23 test blast. Blasting outside of 300 feet of homes continues, he said.
Attention, meanwhile, is turning to the Lake Las Vegas area where Sanders Construction is awaiting a city permit to blast for Woodside Homes. About 30 to 40 people showed up at a meeting two weeks ago to complain about the proposed blasting and potential damage to their upscale homes.
James Sabalos, a Lake Las Vegas resident, said he hopes the city doesn't use the report from the consultant to justify blasting in his area. A detailed study of the geology is needed to determine the effects of ground vibrations in the Lake Las Vegas area, he said.
Sabalos suggested mechanical and other methods to clear the rock formations should be used instead.
Sanders, who has conducted blasting in Crystal Ridge, said he's not surprised by the study's results. He said he has been frustrated at the city's delay in issuing a blasting permit for Lake Las Vegas. Additionally, Henderson's requirement that he meet with residents stirred them up unnecessarily, Sanders complained.
Henderson Councilman Jack Clark said he hopes a solution can be developed that appeases both residents and homebuilders in Lake Las Vegas and other subdivisions. Clark said he doesn't like blasting either, but the city will have to base its decisions on science. Residents wanted the study, but it hasn't yielded the answers they want, he said.
"There are a few folks that want to buy a different lifestyle than the rest of us live, and they have a right to do so," Clark said. "We have to look at it from a scientific standpoint. We have to make sure whatever is done, that houses are not being damaged."
In 2003, residents of Sun City MacDonald Highlands filed a class-action lawsuit against Del Webb Communities, claiming defects in plumbing, roofing, retaining walls and concrete slabs. Edward Song, the residents' attorney, said legal action will be considered for damage residents believe may be caused by blasting.
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