Soil movement unsettles Terraces residents
Wet soil, engineering flaws and gravity are proving to be a destructive combination at the Riverview Terraces condominium complex, two studies suggest.
The condominiums, located on the west side of Midland Avenue at 27th Street, were built at the bottom of the eastern flank of Red Mountain starting in 2000.
Problems were first reported to Glenwood Springs building officials in August 2002. The complaints included trouble in opening and closing doors and windows, and cracks in walls, ceilings and foundations in buildings 1 and adjoined buildings 5 and 6.
Since those initial complaints, the city hired independent structural and geotechnical engineers to evaluate the soil and building movements and to “determine if any life safety issues” exist, according to a Glenwood Springs Building Department news release.
Building officials also checked the emergency doors to be sure they’ll open in case of a crisis and natural gas lines were checked to be sure there was no breakage.
“After receiving and reviewing the engineer’s report, it has been determined that the buildings are safe to occupy at this time,” the department said.
The developer of the condominiums, Riverview Terraces LLC, pulled a repair permit and is evaluating which course of action is best, Grance said.
Jay Harkins, managing member of Riverview Terraces LLC, confirmed there is some settlement of the soil at the condo development and said the group is “working diligently” to remedy the problem.
Once a course of action is chosen, Grance said some residents of the affected buildings might have to temporarily move out while the structural and cosmetic problems are repaired. These moves would most likely be at the developer’s expense, he added.
In all, there are 12 buildings at Riverview Terraces. The initial report came on Aug. 13, 2002, from a tenant of building 1. Since then, Grance said, residents lodged three to four more complaints.
After complaints were lodged by residents of the condos, the building department hired one company, S.K. Peightal Engineers, of Basalt, to study the structural plans and calculations, and hired another local company, H.P. Geotech, of Glenwood Springs, to study the subsoil conditions of the building sites.
Peightal’s structural study points out, “It is evident that the building is experiencing various types of movement.”
The movement is caused by wetting of the underlying soil and by structural design engineering flaws.
It also warns that these flaws “may apply to the other buildings, as well.”
A spokesman for the company that engineered the development, Denver-based York Engineering Services, was not available for comment on Tuesday.
The H.P. Geotech study dealt with the soil conditions under the buildings. The report, sent to the city building department on Nov. 25, points to surface water from runoff and irrigation as the source of subsoil wetting.
Later in the report it said, “Continued wetting of the subsoils will probably cause additional differential settlement.”
Soil settlement not uncommon
Unstable soils are not a new or unknown phenomenon in Colorado, and the problem is known to be especially damaging in the lower Roaring Fork Valley. From Basalt to Glenwood Springs, there is a high susceptibility to collapsible soil and shallow evaporitic bedrock, the Colorado Department of Natural Resources reported in a news release in September 2002.
Collapsible soils and evaporitic bedrock can create two types of hazards. Collapsible soils, also known as hydrocompactive soils, may settle when they become wet. This settlement can be quite rapid, resulting in soil collapse, the department said.
Evaporitic bedrock is composed of evaporite minerals (gypsum and salt) that may dissolve when wet. The dissolution creates voids, fissures, and caverns in the bedrock that can collapse and cause ground subsidence, sinkholes, subsidence troughs and localized depressions.
One local example of this type of soil settlement includes the sinking of Building One at the Sagewood Condominiums in Aspen Junction between Basalt and El Jebel. In November 2000, a water line broke beneath the condos, sending thousands of gallons of water gushing into the ground and weakening the soil enough to cause the concrete foundation to tear from the rest of the building and sink.
Residents were relocated temporarily, but the building was eventually fixed and they were allowed to move back in.
Examples of the damage caused by these soil problems aren’t unique to buildings. According to a report by James M. McCalpin of Geo-Haz Consulting in Crestone, a landslide that occurred in May 2000 at the Powderhorn Ski Area near Grand Junction moved one lift tower three feet down the slope, forcing the area to replace it.
Also, at Buttermilk Ski Area, five towers on one lift lie on a creeping landslide. The remedy included installation of interceptor trenches and drains, plus fabricating an adjustable-track base between the tower and the concrete foundation, McCalpin’s report said.
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