Michigan Administrative Code › Department - Environmental Quality › Drinking Water And Municipal Assistance Division › Mobile Home Parks and Seasonal Motor Home Parks › Part 3 - SEWAGE COLLECTION AND DISPOSAL SYSTEM › Section R. 325.3331 - Sewer design and installation

Current through Vol. 24-12, July 15, 2024
Rule 31.
(1) A
				  sanitary sewer system shall be designed on the basis of an average daily flow
				  of sewage of not less than 200 gallons per mobile home site per day.
(2) A sanitary sewer shall have sufficient
				  capacity to accommodate the maximum hourly sewage flow from the portion of the
				  mobile home park or seasonal mobile home park being served and shall not be
				  less than 4 inches in diameter.
(3)
				  A sanitary sewer shall be installed at a sufficient depth to prevent freezing
				  and at a sufficient slope to maintain a velocity of 2 feet per second at design
				  flow. The following minimum slopes shall be provided, although greater slopes
				  are preferred where possible:
Sewer Size
Minimum Slope in Feet/100 Feet
4 inch.........................................
1.20
6 inch.........................................
0.60
8 inch.........................................
0.40
10 inch.......................................
0.28
12 inch.......................................
0.22
14 inch.......................................
0.17
(4) A sanitary sewer shall be installed with
				  straight alignment between manholes.
(5) A manhole shall be installed at the end
				  of each sewer line, at all changes in grade, size, or alignment, at all
				  intersections, and at distances of not more than 400 feet along sewers. A drop
				  pipe shall be provided for a sanitary sewer entering a manhole at an elevation
				  24 inches or more above the manhole invert. A cleanout may be substituted for a
				  manhole at the end of a lateral not more than 150 feet in length. The flow
				  channel through a manhole shall conform in slope and shape to that of the
				  sanitary sewers.
(6) A sanitary
				  sewer shall be designed to prevent damage from superimposed loads. Proper
				  allowance for loads on the sanitary sewer shall consider the width and depth of
				  trench. When standard strength sewer pipe is not sufficient, extra strength
				  pipe or special construction technique shall be used.
(7) Leakage tests shall be specified by the
				  engineer for sewer construction. Leakage outward or inward shall not exceed 200
				  gallons per inch of pipe diameter per mile per day.
(8) There shall be no connection between a
				  mobile home park or seasonal mobile home park water system and a sanitary
				  sewer. A sanitary sewer or individual sewer service line shall not be laid
				  within 10 feet horizontally of a waterline.
(9) Where a sanitary sewer line crosses a
				  waterline, there shall be a minimum of 12 inches of clear vertical isolation
				  distance between the two. Where conditions require less vertical isolation, the
				  sanitary sewer line shall be encased in concrete for 5 feet each side of the
				  crossing. One full length of waterline shall be centered over the sanitary
				  sewer crossing.
(10) A mobile home
				  sanitary sewer service connection shall incorporate a p-trap installed at a
				  sufficient depth to prevent freezing. The p-trap and riser pipe shall be
				  constructed of cast iron or schedule 40 plastic pipe. The riser shall terminate
				  not less than 4 inches above final grade and shall be located not closer than 5
				  feet from a water service riser. A riser shall be securely capped when not in
				  use.
(11) A mobile home park or
				  seasonal mobile home park shall be served by a common sanitary sewer
				  system.
(12) A site in a mobile
				  home park or seasonal mobile home park shall be provided with an individual
				  sewer connection.