10-144 C.M.R. ch. 241, § 9 - REPLACEMENT SYSTEMS

A. GENERAL

1. General: A replacement system is a disposal system designed to replace an overboard discharge, a malfunctioning system, or any legally existing, nonconforming disposal system, without any increase in water usage, except as allowed in Section 10. The minimum horizontal setback distances between a replacement disposal system and site features are as set forth in Table 9A, except as otherwise authorized in this Section.

Special Note: Site evaluators must always attempt to meet first-time design standards for all disposal system designs, including those for replacement systems, with special attention to systems inside the Shoreland Zone. The reduced setback standards allowed for replacement systems in this section must be used only when meeting first-time criteria is not practical.

2. Existing overboard discharge: Any structure(s) licensed to discharge treated or untreated wastewater or any property to which a valid license has been issued to discharge wastewater to the waters of the state may install a disposal system using replacement system criteria.

3. Replacement System for Overboard Discharge Systems: Replacement of an overboard discharge licensed by the Maine Department of Environmental Protection must conform to provisions of 38 MRS §411-A, which may require removal of the overboard discharge at the time of transfer or renewal.

4. Replacement of non-malfunctioning system: The replacement of a non-malfunctioning disposal system outside the Shoreland Zone with a system based on the current system design flow must meet replacement system criteria. The replacement of a non-malfunctioning disposal system inside the Shoreland Zone with a disposal system based on the current system design flow must meet replacement system criteria and must maintain the existing component setbacks for existing components located inside a Shoreland Zone disturbance buffer. Additional setback reductions from waterbodies/courses inside Shoreland Zoning disturbance buffers require Department approval.

5. Replacement structures: A structure is considered to be a replacement structure if:

a. It is used to replace the original structure which was destroyed by fire or natural disaster by a structure with a design flow that does not constitute an expansion as defined in Section 10(A)(3), which requires an expanded system be installed as required in Section 10(A)(4). The requirements of Section 10 are applicable for all proposed system reuses that exceed the existing system's design flow; or

b. It is exchanged with another structure with a design flow that does not constitute an expansion as defined in Section 10(A)(3) which requires an expanded system be installed as required in Section 10(A)(4). The requirements of Section 10 are applicable for all proposed system reuses that exceed the existing system's design flow.

6. Structures not considered replacement structures: Structures that do not meet the requirements of Section 9(A)(5)(a), 9(A)(5)(b) or Section 10(A)(3) must have disposal systems that meet the requirements for first-time system criteria described in Section 8.

B. SETBACKS AND SITING FOR REPLACEMENT DISPOSAL SYSTEMS

1. Setback Reductions Between Replacement Disposal Systems and Site Features other than Private Potable Water Supplies Authorized by the LPI: If a site evaluator determines that it is impractical to install a replacement disposal system in accordance with setbacks, as set forth in Table 9A, a variance from the Department is required. The LPI may request assistance from the Department regarding the review and approval of any replacement system variance request.

2. Additional Setback Reductions Between Replacement Disposal Systems and a Private Potable Water Supply which may be Authorized by the Department: If a site evaluator determines that it is impractical to install a replacement disposal system in accordance with the setbacks authorized by the LPI, according to Table 9A, from a potable water supply, the Department may authorize additional setback reductions, on a site specific, case-by-case basis, provided that there is no practical alternative, and reductions are minimized.

3. If a site evaluator determines that it is not possible to install a replacement disposal system, pursuant to Table 9A, the site evaluator must document the existing setbacks from the treatment tank and disposal area to the subject well. A replacement system may be designed and installed which does not reduce the existing system's setbacks from the treatment tank and disposal area to the subject well.

4. Disposal fields installed completely in the original ground: If the disposal field is completely installed in original ground, the backfill material must completely cover the disposal fields. The disposal field must be adequately crowned on level disposal fields (3 percent minimum grade) to allow for settling so that surface water will be allowed to drain from the site without ponding.

5. Disposal fields installed partially in or above the original ground: Disposal fields installed partially in or above the original ground must meet the following requirements:

a. Extent of backfill material: The fill layer must include any backfill beneath the disposal field, the shoulders, and the fill extensions surrounding the disposal field on all sides.

b. Shoulder width and slope: The minimum required shoulder width is 3 feet. The finished grade of the shoulder must be sloped at 3 percent away from the disposal field or conform to the slope of the finish grade of the disposal field.

c. Fill extension: At the outside edge of the shoulder, the backfill material must be terminated by sloping the top of the backfill layer downward at a slope of at least 4 horizontal feet for each vertical foot drop (25% slope) to the original ground.

i. The fill extension must reach the existing ground before an existing ground slope of 3:1 (33%) or within 100 feet horizontal distance of the disposal field; or

ii. A retaining wall of no more than 24 inches in height that is located no less than ten (10) feet horizontal distance from the outer edge of the shoulder, located beneath and down slope of the disposal field. This provision applies only to soils with AIII, B, or C limiting factor conditions.

C. HOLDING TANKS

A holding tank is a closed, watertight, non-discharging structure designed and used to store wastewater for periodic removal via pumping, in lieu of a subsurface wastewater disposal system. Holding tanks are designed and constructed to facilitate ultimate disposal of wastewater at another site. Holding tanks are allowed for replacement systems under limited conditions pursuant to Section 9(E), and are subject to the following provisions:

1. Scope: If a site evaluator determines that it is impractical to install a replacement disposal system in accordance with setbacks and other relevant siting criteria, and the LPI agrees, a holding tank may be designed, subject to the following criteria:

a. Annual pumping required: Every holding tank must be pumped at least once a year, providing the system has been used.

b. Seasonal conversion not permitted: Holding tanks cannot be used to satisfy the requirements for a Seasonal Conversion Permit under 30-A MRS §4215 (2), or a first-time system located within the shoreland area of major waterbodies/courses.

c. Water use monitoring: The LPI may require the installation of a water meter to monitor the flow to the holding tank.

d. Reporting: The owner or agent for the owner of a holding tank shall retain for a period of three years the copies of the pumping records, water use records (if required) and the current agreement between the owner and tank pumper. A copy of these records must be made available to LPI upon his/her request.

e. Holding tank specifications: Newly installed holding tanks must be constructed of the same materials and to the same structural specifications as septic tanks, as specified in Section 7(C). They must be either:

(1) of monolithic construction (effective May 1, 1999) below the top of the inlet to the holding tank, or

(2) sealed at the joint with a non-water soluble compound and all holding tanks must have, at a minimum, an 18-inch diameter clean out cover and a 13-by-17-inch inspection cover over the inlet. Risers are required to grade.

f. Installation: Holding tanks must be installed in accordance with Section 7(H).

g. Setbacks: Must meet the setback requirements for treatment tanks.

h. Alarm provisions: The holding tank must have visual and audible alarm devices to assure the tank is always pumped before it is full.

i. Number and size of holding tanks: The installation must have a minimum capacity of at least seven times the daily flow but not less than 1,000 gallons. Multiple tanks must be installed in series.

j. Water conservation: The plumbing in the structure optimizes water conservation and all water closets meet or exceed ASME standard A112.19.2 (1.6 gallons per flush maximum).

D. APPLICATION PROCEDURE

1. LPI approval: A holding tank application requires LPI approval.

2. Application for a holding tank: A completed application for a holding tank prepared by a site evaluator must contain an HHE-200 Form, and a completed holding tank agreement (HHE-233) with the necessary owner and municipality statements.

E. LPI APPROVAL

1. LPI: The LPI may approve the permanent use of a holding tank proposed by a site evaluator to replace a malfunctioning system or an alternative toilet, as follows:

a. Malfunctioning system: The present system poses a threat or a potential threat to ground or surface water quality, to public health or safety, or to the environment; or,

b. Alternative toilet replacement: An alternative toilet may be replaced by a flush toilet and holding tank if the existing structure is served by pressurized water and a legal grey wastewater system including treatment tank and disposal field.

c. Application meets all criteria: The application meets all requirements of Section 9(C).

F. WORK ADJACENT TO OR WITHIN WETLANDS AND WATER BODIES

Replacement Subsurface Wastewater Disposal Systems: Systems designed to replace legally existing systems on previously developed lots are allowed to be installed within or closer to wetlands and waterbodies than specified for first time systems without the need for additional permits from DEP, LUPC and/or ACOE provided that there are no practical alternatives and the reductions to the standards for first time systems are minimized to the extent practical as required by this rule (for more details see Section 13).

TABLE 9A

Setback Distances for Replacement System, Limits of LPI Authority

Site features vs. disposal system components of various sizes	Disposal Fields (total design flow)			Septic Tanks and Holding Tanks (total design flow)
	Less than 1,000 gpd	1,000 to 1,999 gpd	2,000 gpd or over	Less than 1,000 gpd	1,000 to 1,999 gpd	2,000 gpd or over
Wells with water usage of 2,000 or more gpd or public water supply wells	300 feet	300 feet	300 feet	150 feet	150 feet	150 feet
Potable supply well	100 down to 60 feet	200 down to 100 feet	300 down to 150 feet	50 down to 25 feet [a]	100 down to 50 feet [a]	100 down to 50 feet
Water supply line	10 feet	20 feet	25 feet	10 feet	10 feet	10 feet
Water course, major [c]	100 down to 50 feet	200 down to 120 feet	300 down to 180 feet	100 down to 25 feet [a]	100 down to 50 feet	100 down to 50 feet
Water course, minor [c]	50 down to 25 feet	100 down to 50 feet	150 down to 75 feet	50 down to 25 feet	50 down to 25 feet	50 down to 25 feet
Drainage ditches	25 down to 12 feet	50 down to 25 feet	75 down to 35 feet	25 down to 12 feet	25 down to 12 feet	25 down to 12 feet
Slopes greater than 3:1	10 feet	18 feet	25 feet	N/A	N/A	N/A
No full basement [e.g. slab, columns, posts]	15 down to 7 feet	30 down to 15 feet	40 down to 20 feet	8 down to 5 feet	14 down to 7 feet	20 down to 10 feet
Full basement [below grade foundation, frost wall]	20 down to 10 feet	30 down to 15 feet	40 down to 20 feet	8 down to 5 feet	14 down to 7 feet	20 down to 10 feet
Property lines	10 down to 5 feet [b]	18 down to 9 feet [b]	20 ft down to 10 ft [b]	10 down to 4 feet [b]	15 down to 7 feet [b]	20 down to 10 feet [b]
Burial sites or graveyard boundaries, measured from the toe of the fill extension	25 feet	25 feet	25 feet	25 feet	25 feet	25 feet
Stormwater infiltration systems	100 down to 60 feet	200 down to 120 feet	300 down to 180 feet	100 down to 50 feet	100 down to 50 feet	100 down to 50 feet
Wetponds, retention ponds, and detention basins (excavated below grade); Soil filters, underdrained swales, underdrained outlets, and similar structures	50 down to 25 feet [d]	100 down to 50 feet [d]	150 down to 75 feet [d]	50 down to 25 feet [d]	50 down to 25 feet [d]	50 down to 25 feet [d]
Stormwater detention basins (basin bottom at, or above, predevelopment grade)	25 down to 12 feet	50 down to 25 feet [d]	75 down to 35 feet [d]	25 down to 12 feet	25 down to 12 feet	25 down to 12 feet

Notes:

[a] This distance may be reduced to 25 feet, if the septic or holding tank is tested in the LPI's presence and shown to be watertight pursuant to water tightness standards found in Section 7(H)(8) or of monolithic construction.

[b] Additional setbacks may be needed to prevent fill material extensions from encroaching onto abutting property.

[c] All ground disturbance or clearing of woody vegetation necessary for the installation of a subsurface wastewater disposal system that occurs within 100 feet of the normal high water mark of a major or minor water body/course must comply with this rule pertaining to work adjacent to or within wetlands and water bodies (for more details, see Section 13).

[d] The reduced setback distance may be further reduced down to 12 feet if the stormwater structure has an impervious liner and the fill extensions do not encroach onto the stormwater structure.

Notes

10-144 C.M.R. ch. 241, § 9