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TSSH Part 629

Onsite Soil Investigations

Background (629.00)

The National Soil Survey Handbook, Part 655.01(c), provides the following description:

Site-specific soil investigations, testing, interpretation, and evaluations are services that support the design and installation of works and structures or the implementation of agricultural practices, or that test and evaluate research predictions. These technical soil services are part of NRCS technical assistance to individual cooperators or units of government that have signed agreements specifying the services. The intention of services to individual cooperators is usually to help apply a conservation plan. These are described in general terms in district agreements with NRCS. These services are very site specific and often result in design and practice specifications.

Onsite investigations are not intended to provide information for program eligibility (see site-specific evaluation, NFSAM 512.03).

When site-specific investigations are appropriate (629.01)

NRCS technical soil services for site-specific investigations are done:

  • on agricultural lands for USDA program purposes when requested by USDA program participants; or
  • through Federal, State, or local forms of government where there is a memorandum of understanding or a cooperative agreement that lists the services to be provided. For more information, see the National Soil Survey Handbook, Part 655.

GM_430 - Title 430 - Soil Survey
402.6 Limitations on Use and Distribution of Soil Survey Information
A. Soil surveys seldom contain detailed site-specific information and are not designed for use as primary regulatory tools in site-specific permitting decisions, but are useful for broad regulatory planning and application. Official Soil Survey Information is public information and may be interpreted by organizations, agencies, units of government, or others based on their own needs; however, users are responsible for the appropriate application of soil survey information. NRCS will not accept reassignment of authority for decisions made by other Federal, State, or local regulatory bodies. NRCS will not make changes to Official Soil Survey Information, or of any supplemental soil mapping, for purposes related solely to State or local regulatory programs.

The General Manual, Title 430, Section 402.5F states

Supplemental mapping provides more detailed soil maps and information for areas of limited extent as a result of more intensive onsite investigations. It is considered a separate soil map developed for specific needs and is maintained for improved documentation of the reliability of the delineations and attribute data of the Official Soil Survey Information. More detailed supplemental soil maps are not considered changes to the Official Soil Survey Information.

Supplemental mapping should only be done to support official NRCS activities, including the implementation of Farm Bill programs and/or Conservation Technical Assistance. It should not be done simply because a cooperator (who has a conservation plan) has a personal need, such as hoping for a better soil potential rating for purposes of selling property.

How site-specific investigations are done (629.02)

Generally, soil survey information is not adequate for site-specific investigations, and point sampling must be done to collect data for a specific use at a specific location. For example, for a manure storage facility, information on depth to the water table and restrictive layers is very important at the location of the proposed facility. Therefore, soil descriptions and interpretations are needed only at the location of the proposed facility.

It is important to understand what data are needed to make the appropriate interpretations for the proposed use before conducting site-specific investigations. This knowledge can facilitate sampling design and ensure that the appropriate data are collected. For information on the characteristics that are important for a conservation practice, refer to the conservation practice standards in the Field Office Technical Guide.

When assisting other units of government with site-specific soils information, consult with the agency to see whether guidelines and criteria are in place. Make any recommendations regarding the soil characteristics that may be important for interpretation for the proposed use if there are no guidelines or criteria or if they are incomplete.

Order 1 soil surveys and site-specific data collected are supplements to the official soil survey, but they do not replace or change the “official” soil survey. In many cases, mapping at an order 1 level or collecting point data may reveal inclusions within map units of soils that were not named in the official soil survey as well as use-dependent soil properties that are different from the typical soil properties listed for map units in the “official” soil survey.

Any change to the official and published soil survey can be made only when the survey area is designated as being an MLRA soil survey update (NSSH Part 610). The resource soil scientist provides documented evidence of the soil characteristics, including pedon descriptions and any transect notes (geospatially located), to the MLRA Project Office Leader. If the onsite investigation is conducted in a non-MLRA project area (e.g., for conservation planning), the findings are also provided to the State Soil Scientist and can then be used to document the need for a future soil survey update. The field determination of HEL orNHEL is provided to the DC and SC.

It is important that any data collected during site-specific investigations be properly captured for multiple and future uses through Pedon PC and uploaded into NASIS where appropriate. Copies of reports should go to the State Soil Scientist.