A heritage impact assessment is information or a study which describes the impact that a proposed development may have on a protected property. The impact assessment provides a council or regional district board with important decision-making information, prior to issuing approvals, regarding the negative impact of a proposed development on a heritage resource.
A heritage impact assessment is undertaken to determine the potential impacts of a proposed development or site alteration on a heritage resource and recommended mitigation and conservation measures.
A council or regional district board may wish to request a heritage impact assessment in cases where it is considering a proposal that it believes may have a negative impact on:
A heritage impact assessment should not be requested if the information generated will not affect the outcome of the decision-making process.
Negative impacts can include:
The primary objectives of the impact assessment are to:
The heritage assessment process is composed of two principal components: assessment of heritage values and resources and impact management. Assessment is primarily concerned with understanding the historic place and the evaluation and inventory of heritage values and resources located on the site, and the assessment of impacts that might ensue from the development proposed.
Impact management follows directly from assessment and is primarily concerned with managing unavoidable adverse impacts as well as unanticipated impacts. It is important to recognize that the assessment and impact management stages are approached sequentially, and that impact mitigation recommendations are highly dependent upon results and recommendations made in the evaluation and inventory stage. The success of this process is also dependent upon effective communication and cooperation between project proponents and the Heritage Branch, and their mutual respect for development and heritage resource management objectives.
The heritage impact assessment can include:
A local government receives a building permit application for a commercially zoned property in its downtown. The proposed development will require extensive blasting and excavation of the site. The congregation of an adjacent designated church becomes aware of the proposed development and expresses concern to the council that the blasting and excavation work may negatively impact the stability of the church’s rubble foundation and the integrity of the stained-glass window. The congregation is also concerned that shadows cast by the proposed high-rise tower would increase dampness in the church structure and may negatively impact the historic church garden. Council orders the property owner of the proposed development to prepare and submit an impact assessment that addresses the concerns raised by the church congregation.
(Local Government Act, Heritage Conservation, Division 3 — Heritage Review S. 602, source)
Impact assessment may be required
a) to provide the local government or delegate, at the expense of the applicant, with information regarding the possible effects that the activity or action enabled by the approval may have on the heritage property, or
b) to permit the local government or delegate to undertake, at the expense of the local government, studies regarding the matters referred to in paragraph (a) provided that those studies are undertaken promptly.
2. A requirement under subsection (1) must be communicated to the applicant in writing and include specifications of the information to be provided and of the qualifications of any persons undertaking studies to produce the information.
3. Specifications referred to in subsection (2) must not be changed by the local government or its delegate without the agreement of the applicant.
Sources here, here, here and here.