There are areas within the City of Green River that contain differing amounts of expansive soil. The primary area is generally, west of the irrigation canal. If your structure is located in one of these areas there are a few basic precautions you should take to minimize the detrimental effect of the expansive soil on your structure. If you rent your structure it would be in your best interest to share these guidelines with your tenant.

Expansive soil includes mancos shale (which is common in the outlined Sp-1 Overlay Zone) and fine-grained clay. It occurs naturally and is generally found in areas that historically were a seabed or river bottom. Expansive soil is subject to swelling and shrinkage of the soil, varying in proportion to the amount of moisture present in the soil. As water is initially introduced onto the soil (by rainfall or watering), an expansion takes place. When dried out, the soil will contract, often leaving small fissures or cracks. Excessive drying and wetting of the soil will progressively deteriorate structures over the years. This excessive wetting and drying causes damage due to differential settlement within buildings and other improvements.

If your structure is located on expansive soil it is likely that your structure will experience more hairline cracks and movement in the walls and slabs than a structure built on sandy soil. This is due to the native soil in the area, but includes imported material.

   A.   The following suggested guidelines are intended to assist you in planning:

      1.   A written report should be prepared showing location, boundaries and depth of test holes, moisture conditions, recommended soil bearing pressures, potential for expansion and relative density obtained from all tests, prepared by a civil engineer or soils engineer licensed by the State of Utah. Floating adjustable piers are suggested and normally do not require site-specific engineering.

      2.   The Zoning Administrator or building inspector may require tests or additional information if, in their opinion, the conditions or materials are such that special design of the foundations is necessary. Additional information shall be obtained from the Zoning Administrator.

      3.   Rain and irrigation water is strongly recommended to be directed away from the foundations and special landscaping considerations employed. (Ord. 2011-02, 5-10-2011)