(1) If an existing sewage treatment system is present, the department shall review the adequacy of the existing system for the proposed use and the capability of the existing system to operate without risk to public health and without pollution of state waters. To assist the department in making this determination, the applicant shall submit the following information:

(a) evidence demonstrating the proper hydraulic functioning of each existing system;

(b) evidence as to whether each existing system complied with state and local laws and regulations, including permit requirements, applicable at the time of installation; and

(c) evidence that each existing septic tank was pumped within three years prior to the department's review unless the existing septic tank is less than five years old.

(2) Unless a waiver is approved by the department pursuant to ARM 17.36.601, the drainfields and sand mounds for existing systems must be located at least 100 feet from wells.

(3) The applicant shall provide for a replacement area for each existing system. Unless a waiver is approved by the department pursuant to ARM 17.36.601, replacement areas must comply with the requirements of this subchapter.

(4) Existing cesspools, pit privies, and holding tanks must be replaced by a system approved under this subchapter. Existing sealed pit privies must also be replaced, unless they are at a facility owned and operated by a local, state, or federal unit of government, or are at a facility where use of a sealed pit privy is authorized by the Department of Public Health and Human Services.