(a) Any owner or operator of a sewage disposal plant which does not meet the prescribed water quality standards, within 180 days' notice of failure to meet these standards, shall submit an improved sewage disposal plan to the Department of the Environment for approval. The Department of the Environment, within ten days, shall refer copies of the plan to the appropriate county governing unit of the county in which the plant is located, the Department of Natural Resources and, in Montgomery and Prince George's counties, to the Washington Suburban Sanitary Commission and the Maryland-National Capital Park and Planning Commission, for review and recommendation. They have 30 days to respond to the Department of the Environment.

(b) The sewage plan shall indicate necessary improvements required to ensure that purity of the effluent meets required standards, and shall include a time schedule to construct necessary improvements within 3 years.

(c) If the applicant or any unit requests, the Department of the Environment shall hold a hearing on the plan after at least ten days' notice to the applicant and units to which the referral was made. The Department of the Environment shall approve the plan within 90 days after the owner or operator submits the plan. The Department of the Environment may make any amendment or modification it determines, in accordance with the prescribed standards.

(d) If the owner or operator of the sewage disposal plant fails to submit a plan or construct necessary improvements in accordance with the approved plan, the appropriate county governing body of the county, or in Montgomery and Prince George's counties, the Washington Suburban Sanitary Commission, upon 30 days' written notice from the Department of the Environment that compliance has not been made with the requirements of this section, shall proceed to complete the necessary plan and work so the sewage disposal plant will conform to the prescribed standards.