{ "culture": "en-US", "name": "", "guid": "", "catalogPath": "", "snippet": "The extents of the Dipping Bedrock Overlay zone district was established by the Board of County Commissioners by Resolution CC95-134, dated April 11, 1995 and recorded at reception number F0042928 in the records of the Jefferson County Clerk and Recorder, Golden, Colorado. This zone district overlays that portion of any other zone district located in the designated dipping bedrock area and are supplementary to the regulations imposed on the same lands by any underlying zone district or other overlay district.", "description": "

Data Type: Static. Vintage: Per Board of County Commissioners (BCC) resolution <\/SPAN>CC95-134, dated April 11, 1995<\/SPAN>.<\/SPAN><\/P>

The Designated Dipping Bedrock Area (DDBA) defines an area of Jefferson county where heaving bedrock is possible under certain geological and human-influenced conditions. Special consideration is warranted in all phases of development including site exploration and evaluation, facilities design, construction, and subsequent maintenance. In some areas, avoidance may be the best mitigation method.<\/SPAN><\/SPAN><\/P>

Heaving Bedrock Geological Hazard<\/SPAN><\/SPAN><\/P>

Historically, a high rate of damage to roads, utilities, and lightly loaded structures has occurred where steeply dipping beds of expansive claystone bedrock is found near the ground surface. In such areas, ridges of \u201cheaving bedrock\u201d, as large as two feet high, several tens of feet wide, and several hundreds of feet long have been mapped. The ridges form where adjacent, dipping layers of bedrock, each possessing a different potential for expansion, are exposed to water. Damage from heaving bedrock typically is seen within ten years after development and ground deformations may continue for year or decades. This geological hazard is responsible for tens of millions of dollars in excess of maintenance costs to county taxpayers and homeowners. Compared to damage caused by flat-lying expansive soils and bedrock, which are found to the east over much of the Denver metropolitan area, heaving bedrock problems are more complex in nature and difficult to predict, and the resulting damage is often more localized and destructive.<\/SPAN><\/SPAN><\/P>

Considerations for Proposed and Existing Subdivisions<\/SPAN><\/SPAN><\/P>

The Designated Dipping Bedrock Area (DDBA) contains many areas where geological conditions are favorable for development, and where satisfactory performance of homes and other facilities has occurred. Detailed geological/geotechnical investigations should be conducted for proposed developments within the DDBA to delineate areas where favorable conditions occur, such as thick alluvial soils or layers of nonexpansive bedrock. Special mitigative designs must be employed where zones of potentially heaving bedrock are encountered. Existing subdivisions are not subject to most of the overlay district regulations. However, large additions of remedial structural repair work may be subject to minimum foundation design standards and special review by the Building Department. Potential home buyers should be aware that the distribution of areas of damage within the DDBA may be erratic. A home that exhibits structural damage may be located next to other homes that have no damage. When purchasing an existing home within the map area, or any other expansive soil area, the buyer should have a structural engineer conduct a detailed evaluation of the home to ensure that it is structurally sound.<\/SPAN><\/SPAN><\/P>

Geology and Boundaries<\/SPAN><\/SPAN><\/P>

The DDBA contains eight sedimentary formations of Cretaceous age, including the Graneros Shale, Greenhorn Limestone, Carlile Shale, Niobrara Formation, Pierre Shale, Fox Hills Sandstone, and Laramie Formation, and parts of the Arapahoe/Denver/Dawson Formations. The western boundary corresponds to the contact between the Graneros Shale and the underlying Dakota Sandstone on the eastern dip slope of the hogback ridge or near Golden where these units are missing due to faulting, to the mapped location of the Golden Fault. The eastern boundary corresponds roughly to the eastern extent of bedrock which dips at greater than 30 degrees from horizontal. Bedrock layers underlying the DDBA dip to the east or northeast at 30 to 90 degrees from horizontal. The map does not show internal contacts between different bedrock formations, nor does it attempt to delineate areas of natural alluvial deposits that may cover and significantly reduce the heaving potential of the bedrock. <\/SPAN><\/P>

<\/P>

Data is in State Plane Grid Coordinates, Colorado Central Zone, NAD83.<\/SPAN><\/P>

<\/P><\/DIV><\/DIV><\/DIV>", "summary": "The extents of the Dipping Bedrock Overlay zone district was established by the Board of County Commissioners by Resolution CC95-134, dated April 11, 1995 and recorded at reception number F0042928 in the records of the Jefferson County Clerk and Recorder, Golden, Colorado. This zone district overlays that portion of any other zone district located in the designated dipping bedrock area and are supplementary to the regulations imposed on the same lands by any underlying zone district or other overlay district.", "title": "DippingBedrock", "tags": [ "area", "BCC", "bedrock", "clay", "claystone", "county", "damage", "DDBA", "designated", "designation", "destruction", "dipping", "expand", "expansive", "geologic", "geology", "ground", "hazard", "heaving", "Jefferson", "land", "overlay", "resolution", "sandstone", "shale", "soil", "surface", "water", "zone", "zoning. dipping bedrock", "expansive soils", "geologic hazard", "dipping bedrock overlay", "dipping bedrock zone" ], "type": "", "typeKeywords": [], "thumbnail": "", "url": "", "minScale": 500000, "maxScale": 5000, "spatialReference": "", "accessInformation": "The geological boundaries are derived from the following U.S. Geological Survey 1:24,000 geological quadrangle maps: Eldorado Springs (Wells, 1967; Bull. 1221-D), Louisville (Spencer, 1961; GQ-151), Ralston Buttes (Sheridan et al., 1967; P.P. 520), Golden (Van Horn, 1972; I-761-A), Morrison (Scott, 1972; I-790-A), Fort Logan (Lindvall, 1978; GQ-1427), Indian Hills (Bryant et al., 1973; GQ-1073), Littleton (Scott, 1972; Bull. 1121-L), and Kassler (Scott, 1963; P.P. 421-B).", "licenseInfo": "

There are no access and use limitations for this item.<\/SPAN><\/SPAN><\/P>

<\/P><\/DIV><\/DIV><\/DIV>", "portalUrl": "" }