(a)Purpose. The process established by this part uses a planned and phased approach to the assessment of natural resource damages. This approach is designed to ensure that all procedures used in an assessment, performed pursuant to this part, are appropriate, necessary, and sufficient to assess damages for injuries to natural resources.(b)Preassessment phase. Subpart B of this part, the preassessment phase, provides for notification, coordination, and emergency activities, if necessary, and includes the preassessment screen. The preassessment screen is meant to be a rapid review of readily available information that allows the authorized official to make an early decision on whether a natural resource damage assessment can and should be performed.(c)Assessment Plan phase. If the authorized official decides to perform an assessment, an Assessment Plan, as described in subpart C of this part, is prepared. The Assessment Plan ensures that the assessment is performed in a planned and systematic manner and that the methodologies chosen demonstrate reasonable cost.(d)Type A assessments. The simplified assessments provided for in section 301(c)(2)(A) of CERCLA are performed using the standard procedures specified in subpart D of this part.(e)Type B assessments. Subpart E of this part covers the assessments provided for in section 301(c)(2)(B) of CERCLA. The process for implementing type B assessments has been divided into the following three phases.(1)Injury Determination phase. The purpose of this phase is to establish that one or more natural resources have been injured as a result of the discharge of oil or release of a hazardous substance. The sections of subpart E comprising the Injury Determination phase include definitions of injury, guidance on determining pathways, and testing and sampling methods. These methods are to be used to determine both the pathways through which resources have been exposed to oil or a hazardous substance and the nature of the injury.(2)Quantification phase. The purpose of this phase is to establish the extent of the injury to the resource in terms of the loss of services that the injured resource would have provided had the discharge or release not occurred. The sections of subpart E comprising the Quantification phase include methods for establishing baseline conditions, estimating recovery periods, and measuring the degree of service reduction stemming from an injury to a natural resource.(3)Damage Determination phase. The purpose of this phase is to establish the appropriate compensation expressed as a dollar amount for the injuries established in the Injury Determination phase and measured in the Quantification phase. The sections of subpart E of this part comprising the Damage Determination phase include guidance on acceptable cost estimating and valuation methodologies for determining compensation based on the costs of restoration, rehabilitation, replacement, and/or acquisition of equivalent resources, plus, at the discretion of the authorized official, compensable value, as defined in § 11.83(c) of this part.(f)Post-assessment phase. Subpart F of this part includes requirements to be met after the assessment is complete. The Report of Assessment contains the results of the assessment, and documents that the assessment has been carried out according to this rule. Other post-assessment requirements delineate the manner in which the demand for a sum certain shall be presented to a responsible party and the steps to be taken when sums are awarded as damages.51 FR 27725, Aug. 1, 1986, as amended at 59 FR 14281, Mar. 25, 1994