The act sets out standards and regulations for manure collection and storage facilities, and manure application, and designates the Natural Resources Conservation Board (NRCB) as the provincial agency responsible for permitting and enforcement. Alberta’s Ministry of Agriculture and Forestry (AF) is responsible for developing and updating AOPA.

Before 2002, permits for CFOs were issued by local municipalities or health authorities. Many of these permits were issued without manure storage facility construction or design standards. In some cases, permits were not required.

An integral focus of AOPA is to mitigate risks to the environment. In 2006, the NRCB and AF developed a risk management framework policy in consultation with a multi-stakeholder advisory group.

The framework identified the need to prioritize regulation based on risk to the environment. It led to the development and use of an environmental risk screening tool and risk-based compliance initiative, both focused on assessing risk to groundwater at CFOs.

Although the NRCB’s approach to environmental risk assessments and mitigation is based on the best available, current and relevant science, to date there has been limited information specific to Alberta about the effects of manure storage and handling on groundwater quality.

This information on the extent and risk to groundwater of these activities had never been documented and evaluated. In 2009, the NRCB and AF began a joint study to gain a better understanding of manure management activities at CFOs in Alberta and whether manure storage facilities and associated activities such as land application of manure are releasing manure constituents into shallow groundwater resources.

As part of this, AF and the NRCB commissioned two literature reviews of potential effects from manure storage facilities and manure spreading on groundwater quality in Alberta. The reviews found:

• Soil and groundwater contamination can occur from CFOs.
  
  
• Most land application of manure occurs near CFOs, and areas in Alberta with concentrated CFOs were identified as areas where groundwater is most vulnerable to being contaminated by manure.
  
  
• Under current manure application rates, accumulation in the soil profile of nitrogen and phosphorus has the potential to affect groundwater quality.
  
  
• The dominant manure constituent associated with contamination from manure storage at CFOs is ammonium-nitrogen, while the dominant manure constituent associated with contamination from manure spreading is nitrate-nitrogen.
  
  
• In Alberta, relatively thick clay-till aquitards (fine-grained soils) are prevalent throughout much of the landscape, and shallow aquifer systems are typically not extensive, suggesting many sites within the province are stable from a hydrogeological standpoint.
  
  However, deep fractures are common in Alberta’s clay-rich sediments and may increase migration of contaminants to greater depths and into underlying aquifers.
  
  
• Alberta’s regulatory program was considered neither the most stringent nor the most lenient for manure collection and storage. Spreading requirements were similar to other jurisdictions in North America.

The majority of CFOs in Alberta producing liquid manure use below-ground earthen manure storages (EMSes). An EMS constructed before 2002 has the highest potential to leak.

Liquid manure may be stored in an unlined lagoon comprised of natural materials and might have had relatively little consideration given to its construction. It is estimated there are approximately 1,000 hog and dairy facilities in the province and about 650 EMS facilities.

For these facilities, the potential for and rate of leakage would depend on the geologic materials present under or within the EMS.

The study sites

The joint groundwater field research program began in 2009 and concluded in 2017. As a part of this study, five CFO sites were selected as field-scale pilot studies to investigate the effects of CFOs and EMS facilities on groundwater quality: three in central Alberta’s Lacombe-Ponoka region and two in southern Alberta, near Picture Butte.

Monitoring wells were installed at each site.

The three CFOs in central Alberta were dairies. One of the sites in southern Alberta was a combined dairy and feedlot operation while the second was a beef feedlot.

Based on site characterization, geological investigations and monitoring well installation, the dairy CFOs were selected to represent the primary hydrogeological conditions in Alberta affected by manure storage and handling activities.

One site was characterized by sandy soil, two were characterized by thin till over shallow permeable bedrock, and one was characterized by thick clay till.

The research focused on specific EMS facilities at each of the four dairies. At the dairies, the EMSes for liquid dairy manure were the only manure storage facility at these sites. Facilities associated with the two feedlots included outside pens and catch basins.

Research objectives and approach

The research objectives were to:

• Improve our understanding of the effects of manure handling and storage on groundwater quality in Alberta
  
  
• Improve our understanding of the fate and transport of various manure constituents in groundwater beneath CFOs

A broader aspect of the study also looked at groundwater quality changes over time at sites near Picture Butte (an irrigated region which has the highest density of CFOs in Alberta) and examined the effects of land application of manure on groundwater on a regional scale.

This broader aspect of the study also compared relative effects of different manure management activities on groundwater quality and the absolute and relative risks to groundwater quality from EMS facilities and field application of manure.

Research at the five study sites focused on characterizing the contaminant source (i.e., aqueous manure), the hydrogeological and physical controls on the transport of contaminants, the background aqueous and solids chemistry, and the aqueous and solids chemistry within the contaminant plume – and quantifying the geochemical controls on the fate of contaminants.

One hundred and three monitoring wells (water table wells and piezometers) were installed at the five sites, and more than 1,500 groundwater samples were collected and analyzed from 2009 to 2015.

Chloride and nitrogen species (i.e., nitrate and ammonium) were selected as the main indicators of manure and contaminants of concern in groundwater. Chloride and nitrate are highly mobile. Chloride does not undergo biological transformation or sorb to soil and is considered to travel at the same rate as groundwater (i.e., conservatively). It can therefore be used to trace and indicate manure contamination.

Shallow groundwater with chloride concentrations greater than 20 milligrams L-1 is generally regarded as being affected by anthropogenic (human-caused) sources. Nitrate generally occurs naturally at low concentrations in groundwater.

With the exception of geologic nitrate, nitrate levels greater than 3 milligrams L-1 are also considered to be from anthropogenic sources and can result in health effects such as methemoglobinemia (i.e., blue baby syndrome).

Findings

Generally, elevated concentrations of chloride and nitrogen species (primarily nitrate-nitrogen) were observed in monitoring wells surrounding the EMS facilities at all sites, indicating a likely effect from liquid manure storages on shallow groundwater quality.

Elevated nitrate-nitrogen concentrations were observed in one deeper piezometer near one EMS and may indicate downward movement of contaminants at that site.

But on the whole, there was little evidence of elevated chloride or nitrate-nitrogen below 10- to 15-metre depths in the groundwater at the study sites, suggesting limited downward movement of manure constituents. Similar results were observed for catch basins.

Concentration of the indicator parameters appeared to follow normal cycles of use of an EMS at some monitoring wells and normal groundwater trends throughout the year at other monitoring wells.

This suggests the effect of manure on groundwater is not consistent and may be linked to seasonal changes in weather and to manure management activities, such as emptying and filling cycles of EMS facilities, timing of manure application to fields, etc.

An overall increase or decrease in parameter concentrations was not observed during the study period at most EMS monitoring wells.

Data suggested at sites characterized by thin till (less than 6 metres) over shallow permeable bedrock, nitrate-nitrogen and chloride contamination of groundwater reached a distance of at least 120 to 150 metres from the EMS. Monitoring wells were not installed far enough down-gradient to assess the full extent of the plumes.

At the site characterized by permeable groundwater settings (i.e., sandy soil), observed chloride and nitrate-nitrogen migration appeared to be limited to distances of up to 50 metres from the facilities.

At the site characterized by thick clay till, results suggested chloride and nitrate-nitrogen contamination of groundwater from the EMS was restricted to less than 50 metres from the facilities.

Although elevated concentrations in the shallow wells immediately surrounding the EMS were observed, migration further away was not apparent. Contaminant migration may be limited due to a combination of dispersion, dilution, sorption and denitrification processes.

In addition to likely contributions from the EMSes, the study also found evidence in the groundwater of manure constituents from manure piles (temporary and long-term storage) and pens.

These were likely causing comparable (or higher) chloride and nitrate-nitrogen concentrations in groundwater at the sites. High concentrations of chloride and nitrate-nitrogen in water table wells suggested potential contamination of shallow groundwater from these solid manure storage areas at the dairy operations and the feedlots.

While manure seals can form under feedlot pens and could result in relatively lower hydraulic conductivity in soils beneath pens, this alone does not act as an effective liner.

However, active feedlot pens appeared to present less risk to groundwater contamination than areas used for temporary or long-term solid manure storage. Silage storage and septic fields, at or near CFOs, may also be potential sources of effect on groundwater quality.

These findings suggest manure management activities such as stockpiling solid manure, manure spreading, etc., may have a greater effect on groundwater quality than manure storage facilities themselves.

Although individual facilities may not have a large effect, the potential cumulative effect of many CFOs or CFO facilities in a concentrated area may influence groundwater quality.

By improving the scientific and practical understanding of the fate and transport of manure constituents in groundwater at typical Alberta CFO settings, improved management, policy and protection of the groundwater and environment can be achieved.

The results from the greater overall study also provide insights and understanding into the impact of other point- and non-point sources of manure-associated contamination on Alberta groundwater, particularly land application of inorganic and organic fertilizers and the disposal of human waste.

Instrumentation installed during the study may allow for continued monitoring and may also allow researchers to investigate the fate and transport of other emerging contaminants such as pharmaceuticals and viruses, and thus assess their impact on groundwater.

Data analysis and a final report is expected to be complete later in 2017. For more information on the study, go to Alberta Agrigulture and Forestry.  

Mike Iwanyshyn is a senior environment specialist with NRCB. Email Mike Iwanyshyn.