The following shall apply to the design and construction of Subsurface Sewage Treatment Systems:
A. General Requirements.
1. Required Subsurface Sewage Treatment Systems upgrades shall be constructed prior to the issuance of a building permit.
B. Design Requirements.
1. Subsurface Sewage Treatment System designs shall identify an alternate septic site.
2. A minimum of four (4) soil borings or soil test pits shall be required for each Subsurface Sewage Treatment System.
3. Gravity trenches shall consist of a minimum of four (4) equal trenches.
4. Pressurized beds may be allowed on slopes greater than 6 percent, provided the cover soils do not exceed 36 inches over the pipe and the required separation is satisfied.
C. Required Materials.
1. Schedule 40 pipe shall be used from the Structure to the septic tank.
D. Tank Requirements.
1. Holding tanks are prohibited, unless installed to serve an accessory building with limited sewage flow on residential property. Before approving the installation of a holding tank, the Building Official shall consider the suitability of the location of the holding tank, the availability of other alternatives to installation of the holding tank, and any mitigation of potential environmental effects that the Building Official should deem reasonable given the circumstances. Other than stated in this Section, a holding tank shall not be used to satisfy the sewage requirements for a principal use of the property in any zoning district within the City. The owner of a holding tank must enter into a monitoring and disposal contract as described in Section 14-638(B). The contract must be provided to the City and must guarantee the removal of the tank contents before overflow or any discharged.
2. The minimum capacity for lift stations shall be 1,000 gallons.
3. The Subsurface Sewage Treatment System tank capacities shall be as follows:
(a) 2 bedrooms or less = 1000 gallon minimum
(b) 3 bedrooms - 1250 gallon minimum
(c) 4 bedrooms - 1500 gallon minimum
(d) 5 and 6 bedrooms - 2000 gallon minimum
For 7 or more bedrooms, Subsurface Sewage Treatment System tank capacities shall be sized in accordance with “Other establishments” as defined by Minn. R. Ch. 7080.
E. Construction Requirements.
1. An existing or proposed and alternate Soil Treatment Area shall be clearly identified and protected prior to the issuance of a building permit.
2. Soil Treatment Areas, including alternate areas, located on commercial property shall be permanently protected from all vehicle traffic.
3. The maximum depth of maintenance holes shall be six (6) inches.
4. A marker pipe shall be installed for maintenance holes on tanks located below grade.
5. Inspection pipes shall measure a minimum of four (4) inches in diameter.
6. Inspection pipes shall be secured so as to prevent removal from the ground.
7. Design sheets shall be present during on-site inspections.
8. Wiring shall not be located across any septic or lift station tank.
F. Set Back Requirements.
1. Septic tanks shall be placed a minimum of 20 feet from any Building exit.
2. Property line setbacks may be reduced for an SSTS if written consent is obtained from adjacent property owners.
G. Public Buildings, Churches, and Commercial Buildings.
1. Owners of Public Buildings, Churches, and Commercial buildings with a design flow rate of 2000 gallons per day (gpd) shall be required to have a certified individual on staff, as defined by Minn. R. Ch. 7083, or shall have contracted with an MPCA licensed company to maintain and manager on-site Subsurface Sewage Treatment Systems. Such contract shall be on file with the City.
H. Floodplains.
1. An SSTS shall not be located in a floodway or floodplain. Location within the flood fringe is permitted provided that the design complies with this ordinance and all of the rules and statutes incorporated by reference.
I. Determination of Hydraulic Loading Rate and SSTS Sizing.
1. The following tables are hereby adopted by reference and shall be used to size SSTS infiltration areas using the larger sizing factor of the two:
(a) Table IX from Minn. R. part 7080.2150, subp. 3(E) entitled Loading Rates for Determining Bottom Absorption Area f and Absorption Ratios Using Detail Soil Descriptions; and
(b) Table IXa from Minn. R. part 7080.2150, subp 3(E) entitled Loading Rates for Determining Bottom Absorption Area and Absorption Ratios Using Percolation Tests
[§ 14-635, added by Ord. No. 98-5, effective July 30, 1998, amended by Ord. No. 03-02, effective April 10, 2003, amended by Ord. No. 07-02, effective March 1, 2007, amended by Ord. No. 09-02, effective March 5, 2009, amended by Ord. No. 12-02, effective April 5, 2012, amended by Ord. No. 12-04, effective June 14, 2012, amended by Ord. No. 15-01, effective May 7, 2015.]