Homebuyers on their own to check soil stability
The problem of sinking homes in Ironbridge, built on hydrocompactive soils that collapse when they get wet is neither isolated nor new.
Shifting soils have caused millions upon millions of dollars in property damage in Colorado, said Bob Patillo, the structural engineer who worked with Ironbridge homeowners in winning a settlement.
Despite past damages and often-unstable geology, Colorado has no state law or rule to force developers to disclose soils tests to buyers, he said. Homebuyers are left to do their own homework.
Much of the Front Range experiences expansive soils, like clay, that swell when they get wet. And parts of the Front Range, such as Denver, require that developers and builders assume that the soil will get wet to at least 20 feet or more, said Patillo.
Their buildings are designed to anticipate moisture to that depth, and sellers are required to disclose the soil conditions to future buyers.
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However, for consolidation-prone soils, which is what the Western Slope primarily deals with, similar measures are not employed, he said.
State law does not require disclosure to buyer about the soil conditions, and there is no design standard assuming a certain amount of wetting, Patillo said.
The state’s local governments have a wide and not very consistent range of requirements for geotechnical investigations for foundation design, said Patillo.
Two major publications by the Colorado Geological Survey are a handbook for homeowners about swelling soils, and one about collapsible soils.
“A Guide to Swelling Soils for Colorado Homebuyers and Homeowners” is CGS’s bestselling book. It’s often handed over the buyers with their closing documents.
Jonathan White, co-author of “Collapsible Soils in Colorado” and senior engineering geologist for CGS, said he’s well aware of the soils issues in Garfield County.
Buyers of homes on collapsible soils must dig deep, read the land use review letter the CGS writes for the county, go to the building department, request the development application and get the geotechnical report, he said.
“But most people don’t do all that.”
What’s worse, other contractors brought on to work on the property don’t check these resources either, said White. Builders and landscapers will assume that the soil conditions have already been accounted for.
Glenwood Springs has experienced a lot of soil collapse issues, so the city requires an engineered foundation, said Patillo.
“I don’t think there are more soils issues in Glenwood Springs than other areas of the Roaring Fork and Colorado River valleys, but we do enforce the codes for geotechnical investigation and geologic hazards,” said Patrick Seydel, director of Glenwood Springs’ building department, wrote to the Post Independent.
Then the engineer uses the soils and geologic hazards reports to design the buildings’ foundation, wrote Seydel, “and the building department inspects the foundation installation for compliance with the engineered design.”
The reports on a development’s soils and geohazards are public record, he added.
“It would be prudent for any customer to request soils/geohazard reports as part of their due diligence prior to purchase.”
Andrew Schwaller, director of the Garfield County building department, said the county relies on the subdivisions’ site-specific soil testing requirements, which are submitted to the county during the building permit application process.
The county defers to subdivision rules on when to do a soils test, what kind of foundation is built on those soils and when a seller is required to disclose the soil conditions to a buyer.
“Lots outside a subdivision may or may not require a soil test unless the area is known to contain questionable soil characteristics,” Schwaller wrote to the Post Independent.
And while some subdivisions recommend soil testing, when it comes time to permit the building, it’s often waived as an additional expense, said Patillo.
There are a lot of gaps in the way these projects are approved, even for an area with a history of soils and settlement problems, he said.
“As a structural engineer, we want more consistency, but of course that means more regulations or more standardization of regulations,” he said. “Legislation needs to be considered at either the state or local level. This is our greatest geological hazard.”
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