What is Mitigative Excavation?

Mitigative excavation is the process of digging an archaeological site that is threatened either by development or natural erosion. Mitigative excavations have different goals than academic excavations. The goal of mitigative excavations is is to save as much information about the site before it is destroyed, whereas in academic digs the goal is to answer specific questions about how people were using the site in the past.

When a planned development is in direct conflict with a significant archaeological site our normal first recommendation is for a project redesign in order to avoid impacting the site. When a project redesign is not a viable option a mitigative excavation might be required.

Before the excavation begins additional shovel testing may be required to ensure that the boundaries of the site have been confidently established and to identify the most important or valuable part of the site. Using what we have learned from the shovel testing we select areas for excavation blocks. We try to target the places where we’ll get the best return, in scientific information, for the investment of time. These excavation blocks are usually excavated in 1×1 m units. During the excavation layers of a predetermined depth are carefully removed. The sediment is screened and artifacts are collected. While excavating each layer is carefully described and locations of artifacts within the layer are recorded. Any changes in the soils or unusual staining is also described in detail. As each layer is removed photos are taken to further document the process. Once the unit is excavated to its final depth photos and drawings are taken of the unit walls. These photos and drawings will help us to understand the natural formation of the site area by studying the statigraphy. Looking at the layers of the soil can help us to determine if some artifacts in the site are older than others and can help us to understand how long or often the site was used by people in the past.

Mitigative excavations in Alberta typically do not involve excavation of the entire site as you might see in academic research excavations; instead archaeologists first consult with the developer and the government and excavate a sample of the site that focuses on the area of impact, and maximizes the information value of the dig.

Once the mitigative excavation is complete and the final report describing the project has been approved by the government the development will be allowed to proceed.

Mitigative excavations usually move along at a faster pace than academic excavations. This is related to time restrictions associated with development planning and budgetary concerns, as well as our focus on efficiency, and maximizing the return on investment. Academic excavations often take place over many field seasons but mitigative excavations have to be completed before the developer begins construction.

Mitigative excavation is our best tool to preserve archaeological heritage when avoidance isn’t an option, but it’s still a net loss in heritage value. Archaeological sites are non-renewable resources, once they have been destroyed, whether by excavation or development, no more information can be collected about the site.

HRV 4C – What Happens Now?

You have made a plan for a development and reviewed your plan against the Listing of Historic Resources. You’ve found that you have a conflict on your land parcel, it is listed with an HRV of 4C. What does that mean?

An HRV of 4C indicates that an historic resource site is located on that parcel of land, and that one or more First Nations groups have reported that the site is of cultural significance to them. These sites are usually Traditional Use Sites with a historic component, or spiritually significant or religious sites. Some examples include historic cabins or trails, community campsites, prayer trees or other spiritual sites, burials, cemeteries, rock art sites, and mission sites.

Before you can proceed you or your historic resource consultant must submit a Historic Resource Application through OPAC (the Online Permitting And Clearance system) to the Aboriginal Heritage Section of Alberta Culture & Tourism. Aboriginal Heritage will review the development plans against their confidential records of the site and determine whether impacts are likely. If impacts to the HRV 4C site are likely, Aboriginal Heritage will issue site-specific Consultation requirements.

This means you may have to Consult with the First Nations who have Listed the site. More than one group may have an interest in the site because of shared history and land use. Be sure to consult with all interested parties in this matter. Consulting with only one group on overlapping Listings is not sufficient. Alberta Culture will inform you if Consultation is required or not, and with which groups site specific Consultation is required (Listing of Historic Resources, Instructions for Use). It’s very important to understand that any Site-Specific Historic Resource Consultation requirements are separate from and in addition to any other standard Consultation requirements regarding Treaty rights and land use. You may have to go back to First Nations you’ve already Consulted about your project in general, and may have to Consult with different groups or individuals.

Whether you are required to Consult with First Nations groups or not, an HRV of 4C may also result in a requirement for an Historic Resources Impact Assessment. The fact that a specific historic resource has been identified within your land parcel does not mean that the rest of the area has been surveyed and that there is only the one site there. It only indicates that an historic resource site has been reported. An historic resources impact assessment requirement is likely because areas that are considered culturally significant today usually have been considered important for centuries, or millennia. Areas with an HRV of 4C have a high potential to contain additional historic resources such as archaeological sites.

You may be required to redesign your project to avoid the HRV 4C historic resources site. If the site can’t be avoided, mitigation may be required. Mitigation of archaeological and historic sites typically requires extensive shovel testing, detailed block excavations proportional to the percent of the site to be impacted and detailed mapping of the site. Mitigation of impacts to a Culturally Significant site would likely be site-specific, and determined in collaboration with the affected communities.

Our recommendation for HRV 4C conflicts is to identify them early, discuss them with communities in advance, avoid them at the planning stage.

If you don’t know where to start, or would like someone to help you Consult with First Nations contact Kurt or Madeline at 780-472-8878 or toll free at 1-866-873-3846 or email us at [email protected]. We are happy to help.