1.1 This practice covers the criteria for the laboratory verification of Hydrodynamic Separators (HDS) as it relates to the removal of suspended solids in stormwater runoff.

1.2 HDS manufactured treatment devices are placed as offline or online treatment devices along storm drain pipe lines to remove suspended solids and associated pollutants from stormwater runoff. These devices may be used to target removal of other pollutants which are not covered in this standard. The criteria in this standard specifically relate to the removal of silica particles in controlled laboratory conditions, which is considered an appropriate surrogate for predicting the removal of stormwater solids from actual stormwater runoff.

1.3 This practice provides guidelines for independent regulatory entities, collectively referred to as Authority Having Jurisdictions (AHJs), to streamline data requirements for the certification of HDS devices within their jurisdiction. For any given AHJ, additional criteria may also apply.

1.4 Units—The values stated in inch-pound units are to be regarded as standard, except for methods to establish and report sediment concentration and particle size. It is convention to exclusively describe sediment concentration in mg/L and particle size in mm or μm, both of which are SI units. The SI units given in parentheses are mathematical conversions, which are provided for information purposes only and are not considered standard. Reporting of test results in units other than inch-pound units shall not be regarded as non-conformance with this test method.

1.5 Acceptance of test results attained according to this specification may be subject to specific requirements set by a Quality Assurance Project Plan (QAPP), a specific verification protocol, or AHJ. It is advised to review one or all of the above to ensure compliance.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.