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Guidelines add clarity when investigating sites for manure facilities

The subsoil investigation guideline series to help consultants investigate new or expanding manure facilities is now complete.

See event listings and more articles in this edition of Agri-News: March 27, 2023 issue

“These technical guidelines were developed by the Technical Advisory Group, a partnership among the Government of Alberta, the Natural Resources Conservation Board (NRCB) and the agriculture industry, to add clarity to the regulations under the Agricultural Operation Practices Act (AOPA),” says Vince Murray, AOPA engineer with the Alberta government.

As required by the AOPA, a permit must be obtained prior to constructing a new manure storage or manure collection area. Applications for these permits are made to the NRCB. For more information on who requires a permit, see the AOPA Reference Guide.

AOPA addresses groundwater resource protection for all manure facilities (for solid and liquid manure) by requiring either a protective layer or liner as per Section 9 of the Standards and Administration Regulation. A subsoil investigation is usually required to obtain the information necessary to support an application for a new or expanding manure facility.

“Producers must decide the type of groundwater protection they wish to utilize,” explains Murray. “There are several options available: naturally occurring protective layers, compacted soil liners and manufactured liners such as concrete, steel or synthetics (plastic). Sometimes the decision is made by the production system. For example, a concrete floor is often the liner of choice in a barn. At other times, the subsurface soil conditions determine what options are or are not available.”

Information common for all subsoil investigations is found in the technical guideline, Subsoil Investigations for Manure Storage Facilities and Manure Collection Areas. This guideline provides consistent processes and methodologies for determining depth to the water table and the uppermost groundwater resource. The remaining guidelines are used to support investigations for groundwater protection systems using soil either as it occurs naturally, or as a compacted liner.

If the water table and upper groundwater resource conditions are suitable, then the technical guideline, Subsoil Investigations for Naturally Occurring Protective Layers, can be used to determine if natural soil layers meet requirements. This guideline provides recommendations on:

  • the number, location and depth of test holes
  • methods for testing hydraulic conductivity
  • reporting

“The guideline allows for flexibility in the evaluation. Subsoil investigations can incorporate either laboratory test methods or field test methods. Protocols allow for the reduction in the number of hydraulic conductivity tests when soils are consistent across the site. Options are also available when encountering natural variations at the site.”

If a naturally occurring protective layer is not viable, the Subsoil Investigations for Compacted Soil Liners guideline can be used to assess if a compacted soil liner is an option. This guideline provides clarity on:

  • the number of test locations
  • test methods
  • the hydraulic conductivity values used for liner design
  • reporting requirements

“Sometimes an investigation will find the soil conditions do not meet the specific AOPA hydraulic conductivity and thickness requirements,” says Murray. “The regulations, however, do allow protective layers and liners that provide equivalent protection. The final guideline in the series, Determining Equivalent Protective Layers and Constructed Liners, provides a consistent method to determine this equivalency.”

There are 2 potential situations where this equivalency guideline is applicable:

  • the soil layer may have a better hydraulic conductivity than required but not have the thickness, or
  • no soil layer has the hydraulic conductivity required but the layer(s) is thicker than required

This series of guidelines is published on the Open Government Portal and can be obtained from Agriculture and Irrigation’s Manure management guidelines and legislation web page or by calling the Publications Office at 780-427-0391. Dial 310-0000 to be connected toll-free.

They are also available on the NRCB’s web page, under Documents.


Connect with 310-FARM for more information:

Phone: 310-FARM (3276)
Email: [email protected]

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