(1) Approved manual required. Six months after the effective date of ecology's stormwater management manual or six months after the effective date of this chapter, whichever is later, WSDOT shall submit to ecology a highway runoff manual. If WSDOT proposes to adopt a manual other than ecology's stormwater management manual as its highway runoff manual, WSDOT shall formally consult with the tribes and local governments about the contents of the highway runoff manual. The highway runoff manual shall be consistent with ecology's stormwater management manual and shall be adopted by WSDOT only after obtaining ecology's approval. After obtaining ecology's approval, WSDOT shall use the highway runoff manual to direct stormwater management for its existing and new facilities and rights of way in the Puget Sound basin.

(2) Amendments to manual.

(a) Ecology initiates amendments. If ecology amends its stormwater management manual to change or add a BMP or other technical requirement that applies to highways, ecology shall notify WSDOT in writing and send WSDOT a copy of the amendment. This notification shall include ecology's determination as to whether the highway runoff manual complies with the amendment. If the highway runoff manual does not comply with the amendment, WSDOT shall submit proposed amendments within sixty days unless ecology agrees to a time extension. Such proposed amendment shall be subject to ecology's review and approval.

(b) WSDOT initiates amendments. Amendments proposed by WSDOT to the approved highway runoff manual shall be submitted to ecology for review and approval. WSDOT shall formally consult with affected tribes and local governments during the development of proposed amendments. Ecology shall review and approve, conditionally approve or deny the proposed amendments within sixty days from the submittal date.

(3) More stringent standards.

(a) WSDOT shall use the minimum standards established in the highway runoff manual but may use more stringent standards.

(b) When a state highway is located in the jurisdiction of a local government that is required by ecology to utilize more stringent standards to protect the quality of receiving waters, WSDOT shall comply with the same standards to promote uniform stormwater treatment.

(c) WSDOT shall comply with standards identified in watershed action plans for WSDOT rights of ways as required by WAC 400-12-570.

(4) Project coordination. WSDOT shall consult with appropriate tribes and local governments and evaluate local conditions for design, construction, and maintenance of stormwater facilities as indicated in WSDOT's utilities manual. Other agencies and organizations that have an interest or expertise in stormwater may also be consulted. WSDOT, tribes, and local governments are encouraged to jointly develop and maintain stormwater facilities.

(5) Contents of manual. The highway runoff manual shall include, but not be limited to, the following:

(a) BMPs for the control of erosion and sedimentation from construction sites, including standards for operation and maintenance;

(b) Hydrologic analysis procedures, including selection of design storms and estimation of runoff;

(c) Design, operation, and maintenance standards for retention and/or detention facilities and conveyance systems that shall emphasize systems which maximize water quality benefits as well as water quantity control, such as inclusion of biofiltration techniques where practicable;

(d) BMPs for the control of pests, excluding weed control which shall be addressed in the vegetation management program described in WAC 173-270-040;

(e) BMPs for the selection and use of deicing chemicals and traction grit which, as a minimum, shall consist of the following: (i) Traction grit particles should be as large as suitable for application on highways for traction purposes because large particles are less readily transported into waters of the state; (ii) selection and use of deicing chemicals shall include consideration of potential effects on water quality and the beneficial uses of potentially affected waters; (iii) stockpiles containing deicing chemicals shall be investigated for existing and potential water quality problems; and (iv) stockpiles that have an identified problem shall be covered, curbed, diked, placed on an impervious surface, and/or located so runoff can not carry dissolved chemicals into waters of the state; and

(f) BMPs for waste disposal from highway runoff system maintenance.

(6) Experimental BMPs.

(a) WSDOT request. WSDOT may request in writing that ecology approve the use of an experimental BMP for one or several sites. The request shall include, but need not be limited to, a description of: (i) The experimental BMP; (ii) why the experimental BMP is being requested; (iii) why the BMPs in the highway runoff manual are not appropriate; (iv) applicable construction techniques; (v) the site or sites at which use of the experimental BMP is proposed; (vi) the characteristics of the site or sites; (vii) design criteria for the experimental BMP; (viii) maintenance procedures; (ix) cost estimates; (x) monitoring procedures; (xi) the time needed for monitoring; (xii) the anticipated results; (xiii) if appropriate, an approved BMP that could be used if the experimental BMP fails; and (xiv) consultation with interested and affected parties including tribes, local governments, and contiguous property owners.

(b) Ecology review and approval. After reviewing WSDOT's request, ecology may approve, conditionally approve, or deny the use of the experimental BMP for specific sites. Any approval shall be for a period of time not to exceed four years unless ecology determines, upon request and justification by WSDOT, that unusual circumstances justify a longer time period.

(c) Evaluation criteria. In evaluating an experimental BMP, ecology shall consider factors it deems appropriate, including, but not limited to: The experimental BMP's effectiveness in protecting water quality and beneficial uses; its reliability, cost, ease of construction; and maintenance requirements.

(d) BMP status. Before ecology's authorization for WSDOT's use of the experimental BMP expires, WSDOT shall consult with affected tribes, local governments, or property owners. WSDOT shall document the results of the experimental BMP and shall determine whether to request amendment of the highway runoff manual to include the experimental BMP as an approved BMP. Before ecology's authorization expires, WSDOT shall either request an amendment to the highway runoff manual under subsection (2)(b) of this section or inform ecology in writing that it is not proposing to amend the highway runoff manual to include the BMP. Based upon the predicted results in the original request, monitoring data and other information relevant to WSDOT's request, ecology shall determine whether an experimental BMP that is not proposed to be included in the highway runoff manual shall be replaced with an approved BMP.