Site Characterization Study for the Construction of Permanent Nutrient Storage Facilities


Factsheet - ISSN 1198-712X - Copyright Queen's Printer for Ontario
Agdex#: 729
Publication Date: 10/2008
Order#: 08-049
Last Reviewed: October 2015
History: Original Factsheet
Written by: Benoit Lebeau - Engineer, Non-Agricultural Source Material Specialist/OMAFRA; Dale McComb, Environmental Management Specialist/OMAFRA

Table of Contents

  1. Introduction
  2. General Requirements
  3. Stage One Investigation Procedures
  4. Equipment to Conduct a Site Characterization Study
  5. Log and Analysis
  6. Subsurface Condition Requirements for Permanent Nutrient Storages
  7. Summary

Introduction

Part VIII of Ontario Regulation 267/03 (Regulation), entitled Siting and Construction Standards, sets out specific criteria for new or expanding permanent nutrient storage facilities. To protect our groundwater, most new and expanding permanent nutrient storage facilities being built in Ontario must provide two levels of protection — two physical barriers between the nutrients being stored and groundwater.

One barrier is achieved by the engineered structure; the other can be achieved in two ways: one by relying on the characteristics of the natural soil at the site, the other by incorporating a liner in the engineering design of the structure if the natural soil at the site does not meet certain standards. To ensure that the site provides adequate protection, a site characterization study is required under the Regulation prior to the construction or expansion of most permanent nutrient storage facilities.

The Regulation defines a "permanent nutrient storage facility" as a facility for storing a material prescribed by the Regulation (such as manure or runoff), including a storage facility made of earth that is a permanent structure or part of a permanent structure. It does not include:

  • a permanent solid nutrient storage facility that has less than 14 days of storage capacity
  • a permanent liquid nutrient storage facility that has less than 14 days of storage capacity and a maximum depth of liquid nutrient less than 100 mm
  • nutrient application or irrigation systems used to deliver liquid fertilizer to crops
  • a permanent nutrient storage facility used solely as part of a vegetated filter strip system

The Regulation refers to two types of site characterization study: a Stage One investigation and a Stage Two investigation. In most cases, a Stage One investigation will generally be adequate for a new or expanding storage facility, if the site and the structure meet certain minimum criteria. A Stage Two investigation, which must be developed by a professional engineer or geoscientist and accepted by the Ministry of Agriculture, Food and Rural Affairs (OMAFRA), may be considered when the site conditions do not meet the criteria identified in the Regulation. Due to the significant additional investigation required, a Stage Two investigation is often a very costly option.

This Factsheet describes the general requirements for conducting a Stage One investigation and the minimum soil conditions necessary for various types of permanent nutrient storage facilities that are considered acceptable under the Regulation. Some of the information is included in a table, allowing the reader to select a storage type appropriate for the conditions found at a particular site.

General Requirements

There are many factors that can influence where a permanent nutrient storage may be sited, and where a site characterization may be conducted. Sections 63 and 67 of the Regulation sets out the general siting criteria for new or expanding permanent nutrient storage facilities and where a site characterization can be done. It addresses such considerations as proximity to wells, field tiles, surface water and desired location. Most municipalities have adopted by-laws that provide for minimum separation distances between manure storage facilities and neighbouring residences and other land uses. The layout of the farmstead may also dictate where a permanent nutrient storage can be located. Good communication between all parties involved in the project is therefore very important when siting a permanent nutrient storage facility and conducting a site characterization study.

Under Part VIII of the Regulation, a site characterization study must be performed if construction or expansion of the following storage facilities is planned:

  • any permanent liquid nutrient storage
  • certain permanent solid nutrient storage facilities without a concrete floor and located on a farm unit where the number of farm animals is sufficient to generate 300 nutrient units (NU) or more annually

The requirement for a site characterization study for a permanent solid nutrient storage facility depends upon a combination of factors that take into account the floor material, the dimensions and capacity of the storage, and the number of animals present on the farm unit. Table 1 summarizes the requirements for storage facilities in various situations.

If a site characterization study is required under the Regulation, it must be conducted under the supervision of a professional engineer or a professional geoscientist licensed to practise in Ontario. As part of the approval of a nutrient management strategy (NMS) for the construction of any structures referred to above, the investigating professional is required to complete and sign the site characterization section of an Engineer's Commitment Certificate. This demonstrates that a qualified professional has committed to conduct this investigation prior to construction.

Stage One Investigation Procedures

A site characterization study involves soil boring or a test pit investigation to identify critical subsurface elements. These include water table levels, depth to the uppermost bedrock layer or aquifer, as well as geotechnical and hydraulic soil characteristics.

A Stage One investigation requires a minimum of one test hole per 1,000 m2 (10,760 ft2) of the footprint of the proposed structure. The test holes must be located 3–10 m (10–33 ft) outside the perimeter of the footprint, thus protecting the integrity of the soil at the site by leaving it undisturbed.

The minimum required investigation depth for a Stage One investigation varies, depending on the type of storage facility selected:

Permanent liquid nutrient storage facility

  • earthen storages: 2.5 m (8 ft) below the lowest elevation of proposed excavation (i.e., below the excavation for the floor)
  • concrete or steel storages: 1.5 m (5 ft) below the lowest elevation of proposed excavation (i.e., below the excavation for the floor). Note: The professional engineer may choose other equivalent materials for the floor of the structure, as long as they offer the same level of protection as concrete or steel.

Permanent solid nutrient storage facility

  • 0.5–0.9 m (1.64–2.95 ft) below the bottom of the proposed facility, depending on the type of soil material as indicated in Table 1.

    Table 1. Site characterization study requirements for permanent solid nutrient storage facilities.
    Type of storage facility

    Requirements
    • Permanent solid nutrient storages with a concrete floor
    • Permanent solid nutrient storage facilities without a concrete floor that meet all of the following conditions:
    1. a volume of less than 600 m3
    2. a surface area of less than 600 m2
    3. walls with an exposed height of less than 1 m

    No site characterization study required under the Regulation for these structures.

    Permanent solid nutrient storage facilities that do not meet all of the criteria listed above and are proposed at a farm unit that has, or is proposing to have, the capacity to generate at least 300 NU.

    The site characterization study must demonstrate that there is at least:

    1. 0.9 m of soil with at least 15% clay content, or
    2. 0.5 m of hydraulically secure soil

    Permanent solid nutrient storage facility that does not meet all of the criteria listed above, AND is proposed on a farm unit that will generate less than 300 NU.

    A site characterization study is not required but the operation must demonstrate that the floor consists of at least 0.5 m of C or D type soil as defined by the Drainage Guide for Ontario.

Equipment to Conduct a Site Characterization Study

Exploratory equipment such as soil boring machines, backhoes, excavators or other equipment can be used to perform the site characterization study. The choice of equipment, which may depend on the nature of the site being investigated, should be left to a professional engineer or professional geoscientist. Figure 1 shows a typical boring machine used to obtain soil samples.

This image shows a mobile drilling rig in a soybean field. The rig is used to take soil core samples for permeability testing.

Figure 1. A mobile drilling rig is commonly used to take soil core samples for permeability testing.

Log and Analysis

The site characterization study should include a field log that describes soil characteristics such as texture, colour and moisture conditions in the soils as a borehole is being drilled or a pit excavated. Soil samples intended for laboratory analysis should also be collected at 1-m intervals, and for every soil layer encountered that consists of a different soil material. Experienced technical personnel can estimate soil texture by observing a small handful of soil when moistened and kneaded between thumb and forefinger. This technique is known as hand texturing. The depths at which soil samples were taken should be recorded, together with an estimate of the soil texture. Depth to any soil anomalies and their characteristics, as well as depth to water table, should also be noted. Geotechnical companies commonly use standard field log forms to document investigations.

Geologic Anomalies

Geologic or soil anomalies are layers of coarse material lenses, stringers, bedrock drift, large rocks and roots or other organic debris that are imbedded within the subsoil. These irregularities can create seepage paths to groundwater from the nutrient storage facility where they contact the floor or walls of the structure. Permeable anomalous features can also transfer water toward the structure, creating unexpected hydraulic loads that may cause structural complications. Where irregularities are encountered during site excavation, the engineer or geoscientist must develop a strategy to compensate for any potential impacts related to these soil and geologic conditions.

Interpretation of Test Data

All soil analyses must be carried out by a laboratory qualified to analyze geotechnical soil samples in Ontario. The completed field and laboratory tests must be interpreted by a professional engineer or a professional geoscientist.

Resource Information

To aid in the analysis for the site, the professional supervising the site investigation can make use of the following additional sources of information:

  • topographical maps
  • quaternary geology maps
  • hydrogeological or septic suitability reports
  • provincial soils maps
  • Ontario Ministry of the Environment (MOE) well construction records
  • MOE Hydrogeological files and/or maps
  • well-water quality data.

Subsurface Condition Requirements for Permanent Nutrient Storages

The subsurface conditions found at a particular site will confirm whether or not the site is suitable and provide sufficient protection to the groundwater. The minimum subsurface conditions required for a solid nutrient storage facility are listed in Table 1.

Table 2 shows the minimum subsurface conditions for various types of permanent liquid nutrient storage facilities that are considered acceptable under the Regulation. In general, more secure storage facilities must be used where the natural soil and geologic characteristics provide a lower level of groundwater protection. The professional conducting the site characterization study will be in a position to determine what type of storage should be used to ensure adequate protection of the groundwater.

Table 2. Acceptable minimum subsurface condition criteria for different types of permanent liquid storage facilities

Type of Storage:

Unlined concrete or steel storage facilities with reinforced concrete floors

Subsurface Condition Requirements:

Must have, between the bottom of the storage facility and the uppermost identified bedrock layer or aquifer, a minimum of

  • 0.5 m of hydraulically secure soil or 1.0 m of soil comprised of a clay content of at least 10%

Note: A hydraulically secure soil is a natural soil, consistent in nature and able to meet a maximum saturated hydraulic conductivity of 1 x 10–8 m/sec.

See Diagram 1.

This diagram shows the minimum subsurface conditions required for unlined concrete or steel storage facilities with reinforced concrete floors.

Diagram 1. Unlined, reinforced floor

Type of Storage:

Lined concrete or steel storage facilities with reinforced concrete floors

Subsurface Condition Requirements:

Must have a minimum of:

  • 0.5 m of native undisturbed material or compacted granular material between the bottom of the storage facility and the uppermost identified bedrock layer or aquifer

See Diagram 2.

This diagram shows the minimum subsurface conditions required for lined concrete or steel storage facilities with reinforced concrete floors.

Diagram 2. Lined, reinforced floor

Type of Storage:

Unlined concrete or steel storage facilities with unreinforced concrete floors

Subsurface Condition Requirements:

Must have, between the bottom of the storage facility and the uppermost identified bedrock layer or aquifer, a minimum of:

  • 1.0 m of hydraulically secure soil or a minimum of 1.0 m of soil comprised of a clay content of at least 15%

See Diagram 3.

This diagram shows the minimum subsurface conditions required for unlined concrete or steel storage facilities with unreinforced concrete floors.

Diagram 3. Unlined, unreinforced floor

Type of Storage:

Lined concrete or steel storage facilities with unreinforced concrete floors

Subsurface Condition Requirements:

Must have a minimum of:

  • 1.0 m of native undisturbed material or compacted granular material between the bottom of the storage facility and the uppermost identified bedrock layer or aquifer

See Diagram 4.

This diagram shows the minimum subsurface conditions required for lined concrete or steel storage facilities with unreinforced concrete floors.

Diagram 4. Lined, unreinforced floor


Type of Storage:

Lined storage facilities made of earth

Subsurface Condition Requirements:

Must have a minimum of:

  • 2.0 m of hydraulically secure soil between the bottom and sides of the lined storage facility and the uppermost identified bedrock layer or aquifer

See Diagram 5.

This diagram shows the minimum subsurface conditions required for lined storage facilities made of earth.

Diagram 5. Lined, earthen nutrient storage facility


Type of Storage:

Unlined storage facilities made of earth used to store agricultural source materials, other than manure and materials produced by intermediate generators

Subsurface Condition Requirements:

Must have at least:

  • 2.0 m of hydraulically secure soil between the bottom and sides of the facility and the uppermost identified bedrock layer or aquifer

Note: The facility MUST have a maximum storage depth of 3.0 m and a maximum storage volume of 2,500 m3.

See Diagram 6.

This diagram shows the minimum subsurface conditions required for unlined storage facilities made of earth used to store agricultural source material, other than manure and material produced by intermediate generators.

Diagram 6. Earthen runoff storage

The site characterization study must therefore conclusively determine that the site characteristics meet the minimum criteria set out in the Regulation for the type of storage structure proposed, to ensure two levels of groundwater protection. In combination with the required setback distances from water wells, these minimum criteria provide excellent protection against groundwater contamination.

The proposed nutrient storage facility may only be considered if the subsoil conditions meet or exceed the requirements set out in the Regulation. If the requirements are not met for a given site, the options are:

  • evaluate another site
  • propose a facility that is suitable for the site
  • perform a Stage Two investigation as determined by the professional engineer and accepted by a director as outlined by the Nutrient Management Act and its associated Regulation

Summary

Protection of our surface and groundwater resources is important. The type of nutrient storage facility and a study of the natural characteristics of the site are used to determine if additional measures are needed to assure protection for our water.

For more detailed information, see the Nutrient Management Act, 2002, Ontario Regulation 267/03, as amended, at the following site: E-laws.

Nutrient Management Disclaimer 2018

The information in this factsheet is provided for informational purposes only and should not be relied upon to determine legal obligations. To determine your legal obligations, consult the relevant law, www.e-laws.gov.on.ca. If legal advice is required, consult a lawyer. In the event of a conflict between the information in this factsheet and any applicable law, the law prevails.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca