Site Specific Soil Survey Standards

Why are site specific standards needed? Because it protects the public, it protects the consultant, and it lays the groundwork to advance the science.

The familiar county soil mapping publication is designed for planning, not parcel level permitting. On-site stormwater and wastewater treatment capacity, along with erosion and sediment control, drives landowner investment in more detailed soils information.

Site specific standards require more intensive procedures than used for NCSS Order 2 and 3 county soil surveys. It is not about just digging more holes. Consistent with NCSS Order 1 standards, all soil boundaries must be observed in their entirety, all soil unit bodies must be visited.

The site specific standard for Georgia for complex soil conditions requires 4 pedons observed per acre of soil mapped (see this pdf, pages 16-17). A corresponding intensity is implied in the other standards when soil complexity warrants, with some flexibility: the Rhode Island example depicted above has about 1 pedon observed per acre.

The most important and authoritative site specific standards we have are National Cooperative Soil Survey (NCSS) products developed by cooperators for use within individual states. Vermont and New Hampshire have a well established standard, now in version 3, published December 2006 (pdf). NCSS cooperators are developing a similar standard for Rhode Island, described in a pdf. A non-NCSS product is Georgia's Criteria for Level III, aka High Intensity Soil Survey, established in the Georgia Department of Human Resources' current Manual for On-Site Sewage Management Systems. There are likely others I am not aware of.

These have strong similarities. They all set the map scale to between 10 and 200 feet per inch, require contours of 5 feet or less, and specify that the work be performed be certified professionals. They depart in oversight, giving approval authority to the NCSS in the northeast, and to the state in Georgia. As more states adopt site specific standards, they will likely be closely aligned with one of these two oversight models. Your comments are invited.

Further Reading:

Order 1 Soil Survey Standards (from NSSH Part 655 Technical Soil Services)

Order 1 soil survey standards are operational procedures and criteria used to conduct order 1 soil surveys. These standards do not preclude the development of additional criteria.

(1) A soil map, a legend with map symbols and soil names, and soil map unit descriptions that address the soil properties are standards for order 1 soil surveys. The maps include the geographic location and size of the site, the date the soil map was produced, the surveyor's initials, and the map scale.

(2) Order 1 soil surveys require detailed soil pedon descriptions for all map unit components. Taxonomic placement of soil components is not required but may be helpful in the application of the data to other areas.

(3) Describe soil properties according to the procedures outlined in Chapter 3 of the Soil Survey Manual.

(4) Order 1 standards require field observation of the soils within all soil map delineations and of each soil boundary.

(5) Georeference all point data for transects and grid sampling.