HomeMy WebLinkAboutNo 822 Amending the Code About Individual Sewage Treatment Systems
ORDINANCE NO. 822
AN ORDINANCE OF MAPLEWOOD, RAMSEY COUNTY, MINNESOTA, AMENDING THE CITY
CODE ABOUT INDIVIDUAL SEWAGE TREATMENT SYSTEMS (ISTS)
The Maplewood City Council approves the following changes to the Maplewood Code of
Ordinances:
Section 1.This section deletes the following parts of the Maplewood City Code:
ARTICLE V.INDIVIDUAL SEWAGE DISPOSAL SYSTEMS
Sec. 28-76. Individual sewage treatment systems –Conformance to state standards.
The owner or developer must use the city sewer systemwhere available. Where the city engineer
decides that a municipal sewer is not available, any use producing sewage shall have an
individual sewage treatment system. A sewage treatment system means a septic tank and soil
absorption system or other individual or cluster type sewage treatment system. The city requires
a permit to install or alter a sewage treatment system. All individual sewage treatment systems
must meet or exceed the Minnesota Pollution Control Agency’s standards. These standards are
in thedocument titled “Individual Sewage Treatment Systems Standards, Chapter 7080”. The
owner or builder shall provide sufficient soil borings and percolation tests so the city can decide a
site’s suitability for an individual sewage treatment system.
Sec. 28-77. Same –Disposal of effluent.
(a)It shall be unlawful to dispose of the effluent from any onsite sewage system or
holding tank anywhere on the ground surface or in any body of water.
(b)It shall be unlawful to dispose of the effluent from a holding tank, such as in a
recreational vehicle, in any unapproved locations in the city sanitary sewer system.
Sec. 28-78. Nonconforming individual sewage treatment systems.
(a)After December 31, 1995, the city shall not issue a building permit for a new principal
structure or for the addition of a bedroom or bathroom, unless any nonconforming
sewage treatment system on the property meets current standards. The city shall not
consider a sewage treatment system nonconforming if the only deficiency is the
setback of the sewage treatment system from the ordinary high water level of a lake or
creek.
(b)The owner of any nonconforming sewage treatment system the city determines to be
a public nuisance shall bring the system into conformance or stop using the system
within thirty (30) days of receiving written notice from the city.
Section 2.This section adds the following to the Maplewood City Code:
AN ORDINANCE REGULATING THE LOCATION, DESIGN, INSTALLATION, USE
AND MAINTENANCE OF INDIVIDUAL SEWAGE TREATMENT SYSTEMS (ISTS)
WITHIN MAPLEWOOD.
THE CITY OF MAPLEWOOD
INDIVIDUAL SEWAGE TREATMENT SYSTEM ORDINANCE
TABLE OF CONTENTS
SECTION 9-950 TITLE..............................................................................................1
SECTION 9-951 INTENT AND PURPOSE................................................................1
SECTION 9-952 DEFINITIONS
9-952(a) Conflicting Provisions...........................................................................2
9-952(b) Measurement of Distances..................................................................2
9-952(c) Certain Terms......................................................................................2
9-952(d) Definitions............................................................................................2
SECTION 9-953 GENERAL PROVISIONS..............................................................12
9-953 Applicability.............................................................................................12
9-953(a)…………………………………………………………………………………12
9-953(b) Administration by Federal Agencies....................................................12
9-953(c) Administration By State Agencies.......................................................12
9-953(d) Administration of This Ordinance........................................................12
9-953(e) General Requirements........................................................................13
SECTION 9-954 ALTERNATIVE SYSTEMS............................................................46
9-954General ..................................................................................................46
9-955Floodplain Systems.................................................................................46
9-956Greywater System.................................................................................47
9-957Other Toilet Waste Treatment Devices...................................................48
9-958Collector Systems...................................................................................48
9-959Sewage Holding Tanks...........................................................................51
9-960Experimental Systems............................................................................52
SECTION 9-961 OPERATION AND MAINTENANCE..............................................53
9-961General Requirements........................................................................53
9-961(a) Maintenance of Septic Tanks..............................................................53
9-961(b) Maintenance of System Components.................................................54
9-961(c) Activities on the Soil Treatment Area .................................................54
9-961(d) Disposal of Septage............................................................................54
SECTION 9-962 ADMINISTRATION........................................................................54
9-962(a) Applicability.........................................................................................54
9-962(b) Enforcement........................................................................................54
9-962(c) Board of Adjustment and Appeals.......................................................55
9-962(d) Permits Required................................................................................55
9-962(e) Inspections Required..........................................................................56
SECTION 9-963 LICENSING AND PERMITS..........................................................57
9-963(a) Licensing.............................................................................................57
9-963(b) Permits................................................................................................57
9-963(c) Permit Applications..............................................................................57
9-963(d) Term of Permit....................................................................................58
9-963(e) Permit Revocation...............................................................................58
SECTION 9-964 ENFORCEMENT............................................................................58
9-964(a) Violations and Penalties......................................................................58
9-964(b) Enforcement........................................................................................58
9-964(c) Public Health Act.................................................................................58
SECTION 9-965 EFFECTUATION.............................................................................59
9-965(a) Separability.........................................................................................59
CITY OF MAPLEWOOD, MINNESOTA
INDIVIDUAL SEWAGE TREATMENT SYSTEM ORDINANCE
SECTION 9-950. TITLE
9-950.Short Title.This Ordinance shall be known, cited and referred to as the
Individual Sewage Treatment System (ISTS) Ordinance, except as referred to herein,
where it shall be known as, "this Ordinance".
SECTION 9-951. INTENT AND PURPOSE
9-951.Purpose.This Ordinance is adopted to provide minimum standards and criteria to
individual sewage treatment systems for the purpose of:
(1)Protecting the health, safety, and welfare of the
residents of the city, present and future.
(2)Regulating the location, design, installation, use and
maintenance of individual sewage treatment
systems (ISTS) so as to prevent contamination of
the surface and ground waters within the
community.
(3)Protecting the individual water supply wells in the
city from contamination by inadequate, improperly
designed, located, installed or maintained individual
sewage treatment systems.
(4)Providing for the orderly development of areas of the
city that are not served by central public systems.
Also to help preclude the need to install central
public sewer systems in areas not currently planned
for central public sewer systems.
(5)These standards are not intended to cover systems
treating industrial or animal waste or other
wastewater that may contain hazardous materials.
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SECTION 9-952. DEFINITIONS.
9-952(a) Conflicting Provisions.In the event of conflicting provisions in the text of this
Ordinance, and/or other ordinances, the more restrictive provisions shall apply. The City
shall determine which is more "restrictive" and appeals from such determination shall be
made in the manner provided herein.
9-952(b) Measurement of Distances.Unless otherwise specified all distance shall be
measured horizontally.
9-952(c) Certain Terms.For the purposes of these standards, certain terms or words
used herein shall be interpreted as follows: the words "shall" and "must" are mandatory,
the words "should" and "may" are permissive.
9-952(d) Definitions.
(1)Absorption Area."Absorption area" means the area
below a mound that is designed to absorb sewage tank
effluent.
(2)Additive, Individual Sewage Treatment System.
"Additive, individual sewage treatment system" means a
product that is added to the wastewater or to the system to
improve the performance of an individual sewage treatment
system. These are not recommended and some are illegal
and harmful to the system.
(3)Aerobic Tank."Aerobic tank" means any sewage tank
that uses the principle of oxidation in thedecomposition of
sewage by the introduction of air into the sewage.
(4)Alternate Site."Alternate Site" means that portion of real
property that is designated by a licensed ISTS Professional
and approved by the City to be protected from all vehicular
traffic, construction and other disturbances. The site must
be maintained in its original, natural soil condition so a
future individual sewage treatment system or device may
be constructed which meets all Ordinance requirements
when the original ISTS malfunctions, becomes non-
repairable or when it fails to comply with the Ordinance.
(5)Alternative System."Alternative system" means an
individual sewage treatment system employing such
methods and devices as presented in Section 9-954.
(6)As-builts."As-builts" means drawings and documentation
specifying the final in-place location, size, and type of all
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system components. These records identify the results of
materials testing and describe conditions during
construction. As-builts also contain a certified statement.
(7)At-grade System."At-grade system" means a pressurized
soil treatment system where sewage tank effluent is dosed
to a drain field rock bed that is constructed on original soil
at the ground surface and covered by loamy soil materials.
(8)Baffle."Baffle" means a device installed in a septic tank
for proper operation of the tank and to provide maximum
retention of solids, and includes vented sanitary tees and
submerged pipes in addition to those devices that are
normally called baffles.
(9)Bedrock."Bedrock" means that layer of parent material
that is consolidated and unweathered.
(10)Bedroom."Bedroom" means any room within a dwelling
that might reasonably be used as a sleeping room.
(11)Building Drain."Building drain" means that part of the
lowest piping of the drainage system that receives the
sewage discharge inside the walls of the building and
conveys it to the building sewer beginning at least one foot
outside the building footings.
(12)Building Sewer."Building sewer" means that part of the
drainage system that extends from the end of the building
drain and conveys its discharge to an individual sewage
treatment system.
(13)Capacity."Capacity" means the liquid volume of a sewage
tank using inside dimensions below the outlet.
(14)Certified Statement."Certified statement" means a
statement signed by a licensed installer or qualified
employee certifying that work was completed in accordance
with applicable requirements.
(15)Cesspool."Cesspool" means an underground pit or
seepage pit into which raw household sewage or other
untreated liquid waste is discharged and from which the
liquid seeps into the surrounding soil. See Section 953(d)
(4).
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(16)Chambered System."Chambered system" means a soil
treatment system where sewage tank effluent is discharged
to a buried structure creating an enclosed open space with
the original soil surface to act as a surface for the infiltration
of sewage tank effluent.
(17)
Clean Sand."Clean sand" means a soil texture composed
by weight of at least 25 percent very coarse, coarse, and
medium sand varying in size from 2.00 millimeters (sieve
size 10) to -.25 millimeters (sieve size 60), less than 40
percent fine or very fine sand ranging in size between 0.25
millimeters and 0.05 millimeters (sieve size 270), and no
more than ten percent smaller than 0.05 millimeters and no
larger than 2.00 millimeters. Clean sand also means a soil
texture that meets American Society for Testing and
Materials (ASTM) specification C-33 (fine aggregate for
concrete) or Minnesota Department of Transportation
(MNDOT) specification 3126 (fine aggregate for Portland
cement concrete).
The ASTM specificationis found in the current addition of
ASTM Standards, which is incorporated by reference. This
document is provided by the American Society for Testing
and Materials located at 1916 Race Street, Philadelphia,
PA 19103-1187.
The MNDOT specification is found in the MNDOT Standard
Specifications for Construction, 1988 Edition, and the May
2, 1994, Supplemental Specifications, which are
incorporated by reference. These documents are provided
by MNDOT located at 395 John Ireland Boulevard, Saint
Paul, MN 55155. All references can be found at the
Minnesota State Law Library, Judicial Center, 25
Constitution Ave., Saint Paul, MN 55155, and are not
subject to frequent change.
(18)Department."Department" means the City of Maplewood
Community Development Department.
(19)DNR."DNR" means the Minnesota Department of Natural
Resources.
(20)Distribution Box."Distribution box" means a device
designed to concurrently and equally distribute sewage
tank effluent by gravity to a soil treatment system.
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(21)Distribution Device."Distribution device" means a device
used to receive and transfer effluent from a supply pipe to
distribution pipes or down slope supply pipes, or both.
These devices are commonly known as drop boxes, valve
boxes, distribution boxes, or manifolds.
(22)
Distribution Medium."Distribution medium" means the
material used to distribute the sewage tank effluent within a
soil treatment system. This medium includes drain field
rock, gravel-less drain field pipe in a geo textile wrap, or a
chambered system.
(23)
Distribution Pipes."Distribution pipes" means perforated
pipes that are used to distribute sewage tank effluent in a
soil treatment system.
(24)Dosing Chamber, or Pump Pit, or Wet Well."Dosing
chamber, or pump pit, or wet well" means a tank or
separate compartment following the sewage tank that
serves as a reservoir for the dosing device.
(25)Dosing Device."Dosing device" means a pump, siphon,
or other device that discharges sewage tank effluent from
the dosing chamber to the soil treatment system.
(26)Drain field Rock."Drain field rock" means crushed
igneous rock, or similar insoluble, durable, and decay-
resistant material with no more than five percent by weight
passing a ¾ inch sieve and no more than one percent by
weight passing a number 200 sieve. The size shall range
fromthree-fourths inch to 2½ inches.
(27)Drop Box."Drop box" means a distribution device used for
the serial gravity application of sewage tank effluent to a
soil treatment system.
(28)Dwelling."Dwelling" means any building or place used or
intended to be used by human occupants as a single family
or two family unit.
(29)Failing System."Failing system" means any system that
discharges sewage to a seepage pit, cesspool, drywell, or
leaching pit andany system with less than three feet of soil
or sand between the bottom of the distribution medium and
the saturated soil level or bedrock.
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(30)Gas Deflecting Baffle."Gas deflecting baffle" means an
obstructing device on the septic tank outlet thatlimits the
escape of solids that are carried by septic tank gases.
(31)Gravel-less Drain Field Pipe."Gravel-less drain field
pipe" means a distribution medium consisting of a
corrugated distribution pipe encased in a geo textile wrap
installed in atrench.
(32)Grey water."Grey water" means liquid waste from a
dwelling or other establishment produced by bathing,
laundry, culinary operation, and from floor drains
associated with these sources, and specifically excluding
toilet waste.
(33) Hazardous Materials."Hazardous materials" means any
substance which, when discarded, meets the definition of
hazardous waste in MN Rules Chapter 7045.
(34)Holding Tank."Holding tank" means a watertight tank for
storage of sewage until it can be transported to a point of
approved treatment and disposal.
(35)Imminent Threat to Public Health or Safety."Imminent
threat to public health or safety" means situations with the
potential to immediately and adversely impact or threaten
public health orsafety. At aminimum, ground surface or
surface water discharges, and any system causing sewage
backup into a dwelling or other establishment, shall
constitute an imminent threat.
(36)Impermeable."Impermeable" with regard to bedrock,
means a bedrock having no cracks or crevices and having
a vertical permeability slower than one inch in 24 hours.
With regard to soils, a soil horizon or layer having a vertical
permeability slower than 0.025 inch in 24 hours shall be
considered impermeable.
(37)Individual Sewage Treatment System (ISTS)."Individual
sewage treatment system" means a sewage treatment
system, or part thereof, serving a dwelling, or other
establishment, or group thereof, which uses subsurface soil
treatment and disposal.
Invert."Invert" means the lowest point of a channel inside
(38)
a pipe.
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(39)Maximum Monthly Average Daily Flow."Maximum
monthly average daily flow" means the 30-day average
daily flow for the highest consecutive 30-day period during
the year.
(40)Mottling."Mottling" means a zone of chemical oxidation
and reduction activity, appearing as splotchy patches of
red, brown, orange, and gray in the soil, which are less
than 2 chroma.
(41) Mound System."Mound system" means a system where
soil treatment area is built above the ground to overcome
limits imposed by proximity to water table or bedrock, or by
slow permeable soils.
(42)Ordinary High Water Level."Ordinary high water level"
means the boundary of public waters and wetlands, that is
an elevation delineating the highest water level maintained
for a sufficient period of time to leave evidence upon the
landscape, commonly that point where the natural
vegetation changes from predominantly aquatic to
predominantly terrestrial.
For watercourses, the ordinary high water level is the
elevation of the top of the bank of a channel. For reservoirs
and flowages the ordinary high water level must be the
operating elevation of the normal summer pool.
(43)Original Soil."Original soil" means naturally occurring
inorganic soil that has not been moved, smeared,
compacted, nor manipulated with construction equipment.
(44)Other Establishment."Other establishment" means any
public or private structure other than a dwelling that
generates sewage.
(45)Owner."Owner" means all persons having possession of,
control over, or title to an individual sewage treatment
system.
(46)Percolation Rate."Percolation rate" means the time rate
of drop of a water surface in a test hole as specified in
Section 953(d) (12).
(47)Permitting Authority."Permitting authority" means any
county, municipality or state agency that administers the
provisions of these standards.
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(48)Plastic Limit."Plastic limit" means a soil moisture content
below which the soil may be manipulated for purposes of
installing a soil treatment system, and above which
manipulation will cause compaction and puddling. The soil
moisture content at the plastic limit can be measured by
American Society for Testing and Materials (ASTM) test
number D4318-84.
(49)Previously Developed Site.Land already containing a
dwelling or other establishment.
(50)
Public Health Nuisance.Public health nuisance means
any activity or failure to act that adversely affects the public
health.
(51)Public Waters."Public waters" means any public waters
or wetlands as defined in Minnesota Statutes, identified as
public waters or wetlands by the inventory prepared
pursuant to Minnesota Statutes.
(52)Replacement."Replacement" means the replacement of
an existing individual sewage treatment system.
(53)Required Absorption Width."Required absorption width"
means that width, measured in the direction of the original
land slope and perpendicular to the original contours, which
is required for the sewage tank effluent to infiltrate into the
original soil according to the allowable loading rates in
Section 9-953(20) Table V.
(54)Restaurants."Restaurants" shall mean any place where
food is prepared and intended for individual portion service
regardless of whether consumption is on or off the
premises or whether there is a charge for the food although
this does not include private homes.
(55)Saturated Soil."Saturated soil" means the highest
elevation in the soil where periodically depleted oxygen
levels occur because of soil voids being filled with water.
The presence of soil mottling or other information
evidences saturated soil.
(56)Seepage Bed."Seepage bed" means an excavated area
larger than 36 inches in width that contains drain field rock
and has more than one distribution pipe.
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(57)Seepage Pit, or Leaching Pit, or Dry Well."Seepage pit,
or leaching pit, or dry well" means an underground pit into
which a sewage tank discharges effluent or other liquid
waste and from which the liquid seeps into the surrounding
soil through the bottom and openings in the side of the pit.
(58)
Septage."Septage" means those solids and liquids
removed during periodic maintenance of a septic or aerobic
tank, or those solids and liquids that are removed from a
toilet, waste treatment device, or a holding tank.
(59)Setback."Setback" means a separation distance
measured horizontally.
(60)Sewage."Sewage" means any water carried domestic
waste, exclusive of footing and roof drainage, from any
industrial, agricultural, or commercial establishment, or any
dwelling or any other structure. Domestic waste includes
liquid waste produced by toilets, bathing, laundry, culinary
operations, and the floor drains associated with these
sources, and specifically excludes animal waste and
commercial or industrial wastewater.
(61)Sewage Flow."Sewage flow" means flow as determined
by measurement of actual water use or, if actual
measurements are unavailable, as estimated by the best
available data.
(62)Sewage Tank."Sewage tank" means a watertight tank
used in the treatment of sewage and includes, but is not
limited to, septic tanks and aerobic tanks.
(63)Sewage Tank Effluent."Sewage tank effluent" means
that liquid which flows from a septic or aerobic tank under
normal operation.
(64)Septic Tank."Septic tank" means any watertight, covered
receptacle designed and constructed to receive the
discharge of sewage from a building sewer, separate solids
from liquid, digest organic matter, and store liquids through
a period of detention, and allow the clarified liquids to
discharge to a soil treatment system.
(65)Shoreland."Shoreland" means land located within the
following distances from public waters: 1,000 feet from the
ordinary high water mark of a lake, pond or flowage; and
300 feet from a river or stream or the landward extent of a
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floodplain designated by ordinance on such a river or
stream, whichever is greater.
(66)Site."Site" means the area bounded by the dimensions
required for the proper location of the soil treatment
system.
(67)Slope."Slope" means the ratio of vertical rise or fall to
horizontal distance.
(68)Soil Characteristics, Limiting."Soil characteristics,
limiting" means those soil characteristics that preclude the
installation of a standard system, including evidence of
water table or bedrock and percolation rates faster than
one-tenth or slower than 60 minutes per inch.
(69)Soil Textural Classification."Soil textural classification,"
where soil particle sizes or textures are specified in this
chapter, they refer to the soil textural classification in the
Soil Survey Manual, Handbook No. 18, United States
Department of Agriculture, 1993.
(70)Soil Treatment Area."Soil treatment area" means that
area of trench or bed bottom that is in direct contact with
the drain field rock of the soil treatment system, and for
mounds, that area to the edges of the required absorption
width and extending five feet beyond the ends of the rock
layer.
(71)Soil Treatment System."Soil treatment system" means a
system where sewage tank effluent is treated and disposed
of below the ground surface by filtration and percolation
through the soil, and includes those systems commonly
known as seepage bed, trench, drain field, disposal field,
and mounds.
(72)Standard System."Standard system" means an individual
sewage treatment system employing a building sewer,
sewage tank, and the soil treatment system consisting of
trenches, seepage beds, or mounds that are constructed
on original soil that has a percolation rate equal to or faster
than 60 minutes per inch.
(73)Surface Water Flooding."Surface water flooding" means
the 100-year floodplain along rivers and streams as defined
by the Department of Natural Resources, or in the absence
of such data, as defined by the largest flood of record; on
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lakes, high water levels as determined or recorded by the
Department of Natural Resources or, in the case of no
Department of Natural Resources record, by local records
or experience. Other surface water flooding or high water
areas should be determined by local information.
(74)
Ten-year Flood."Ten-year flood" means that flood which
can be expected to occur, on an average, of once in ten
years; or the level to which flood water’s have a ten percent
chance of rising in any given year.
(75)Toilet Waste."Toilet waste" means fecal matter, urine,
toilet paper, and any water used for flushing.
(76)Toilet Waste Treatment Devices."Toilet waste treatment
devices" means privies and other devices including
incinerating, composting, biological, chemical, recirculating,
or holding tanks.
(77)Water Table."Water table" means the highest elevation in
the soil where all voids are filled with water, as evidenced
by presence of water or soil mottling or other information.
(78)Watertight."Watertight" means a sewage tank constructed
so that no water can get into or out of the sewage tank
except through the inlet and outlet pipes.
(79)Wild and Scenic River Land Use District."Wild and
scenic river land use district" means those lands
designated by the commissioner of the Department of
Natural Resources as the protected land corridor along
those rivers or river segments designated as wild, scenic,
or recreational rivers.
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SECTION 9-953. GENERAL PROVISIONS
9-953Applicability.
9-953 (a)The owner, builder or developer of a property must connect to the city sewer
within one (1) year system when building or remodeling a structure where the building or
use produces sewage. If municipal sanitary sewer is not available to a site or property, then
any use, buildingor structure producing sewage shall have an individual sewage treatment
system (ISTS). The city engineer shall determine if municipal sewer is available to a site or
a property.
9-953(b) Administration by Federal Agencies.Industrial wastewater systems and
individual sewage treatment systems serving more than 20 persons (1200 gallons per
day) are regulated by the United States Environmental Protection Agency as Class V
injection wells under Code of Federal Regulations Title 40 Part 144.
9-953(c) Administration By State Agencies.For an individual sewage treatment
system, or group of individual sewage treatment systems, that are located on adjacent
properties and under single ownership, the owner or owners shall make application for
and obtain a state disposal system permit if the individual sewage treatment system or
systems are designed to treat an average daily flow greater than 10,000 gallons per day.
The systems must, at a minimum, conform to the requirements of these standards.
For dwellings such as rental apartments, town houses, resort units, rental cabins,
and condominiums, the sum of the flows from all existing and proposed sources under
single management or ownership will be used to determine the need for a state disposal
system permit.
Individual sewage treatment systems serving establishments or facilities licensed
or otherwise regulated by the State of Minnesota shall conform to the requirements of
these standards.
Any individual sewage treatment system requiring approval by the State of
Minnesota shall also comply with this ordinance and all local codes and ordinances.
9-953(d) Administration of This Ordinance.All individual sewage treatment systems
installed after the adoption of this ordinance and all alterations, extensions, modifications
or repairs to existing systems, irrespective of the date of original installation, shall be
regulated in accordance with all requirements of this ordinance.
Existing systems that show evidence of sewage tank effluent discharge to the ground
surface, ground or surface waters or otherwise represent an imminent threat to public
health or safety shall be replaced within thirty (30) days of notice and order to comply by
the department. Any further surface discharge of effluent must be stopped immediately
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(by such methods as reducing or stopping all water use, or pumping the tank as
necessary) until such time as the system is replaced. All tanks taken out of service must
be properly abandoned. (See Section 9-953(e)(16).
9-953(e) General Requirements.
(1)Surface Discharge.Unless specifically permitted by the Minnesota
Pollution Control Agency (MPCA), sewage, sewage tank effluent, or
seepage from a soil treatment system shall not be discharged to the
ground surface, abandoned wells, orbodies of surface water, or into any
rock or soil formation the structure of which is not conducive to
purification of water by filtration, or into any well or other excavation in
the ground.
All new or existing systems which discharge to surface watersor the
ground surface must obtain either a National Pollutant Discharge
Elimination System (NPDES) or StateDisposal System Permit from the
MPCA and shall comply with all requirements pertaining thereto.
(2) Treatment Required.The system, or systems,shall be designed to
receive all sewage from the dwelling, building, or other establishment
served. Chemically treated hot tub or pool water, footing, roof drainage,
or garage floor drains shall not enter any part of the system. Products
containing hazardous materials must not be discharged to the system
other than a normal amount of household products and cleaners
designed for household use. Substances not used for household
cleaning, including motor oil, solvents, pesticides, flammables, photo
finishing chemicals, or dry cleaning chemicals, must not be discharged to
the system.
(3) System Components.The system shall consist of a building sewer,
sewage tank, and soil treatment system. All sewage shall be treated in a
sewage tank or toilet waste treatment device, and the sewage tank
effluent shall be discharged to the soil treatment system.
(4) Prohibited Installations.Cesspools, seepage pits, dry wells, and
leaching pits shall not be installed and shall not remain in operation.
(5)Location.Sewage treatment systems and each component thereof shall
be located and installed to insure that, with proper maintenance, it will
function in a sanitary manner, will not create a nuisance nor contaminate
any domestic water supply well.
The location of a system shall consider lot size and configuration,
proposed structures and other improvements, topography, surface
drainage, soil conditions, depth to ground water, geology, existing and
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proposed water supply wells, accessibility for maintenance, and
expansion or replacement of the system.
Installation of systems in low swampy areas, drainage swales or area
subject to recurrent flooding is prohibited. Systems shall not be located
within utility or drainage easements nor within dedicated public orprivate
rights-of-way.
(6) Clear Water Waste.Uncontaminated clear water waste from
geothermal heat pump installations shall not be introduced into individual
sewage treatment systems. Such waste may be discharged to the
ground surface or to a body of water, however in no case shall surface
discharge be permitted where such discharge encroaches on an
adjoining property or public way. Where subsurface disposal is provided,
such installation shall be separated from the required sewage treatment
site and shall be designed and sized as prescribed for a standard soil
treatment system.
(7) System Sizing.Where the construction of additional bedrooms, the
installation of mechanical equipment, or other factors likely to affect the
operation of the system can be reasonably anticipated, the installation or
expansion of a system for such anticipated need shall be required.
(8)Site Evaluation.Before the city issues a building permit for new
construction or to add bedrooms to existing homes, or a permit to install
an individual sewage treatment system, or approval in the case of
subdivision of land, a field investigation shall be conducted by the
department or other agent of all proposed sites for sewage treatment
systems. Such investigation shall includean evaluation as to:
(a)depth to the highest known or calculated ground water table or
bedrock;
(b)soil conditions, properties, and permeability;
(c)slope;
(d)the existence of lowlands, local surface depressions, and rock
outcrops;
(e)all setback requirements from: existing and proposed buildings;
property lines; sewage tanks; soil treatment systems; water supply
wells; buried water pipes and utility lines; the ordinary high water
level of public waters; and the location of all soil treatment
systems and water supply wells on adjoining lots within 100 feet of
the proposed soil treatment system, sewage tank, and water
supply well; and
14
(f)surface water flooding probability.
(9) Soil Testing.Applicants for sewage treatment system permits,
site or subdivision approvals will be required to submit soil test
data derived from soil borings and percolation tests for each
proposed site or installation. The minimum testing shall be that
necessary to verify suitable conditions for two complete soil
treatment systems including detailed site plan and design. No
permit will be issued until a detailed system design is submitted
for the current proposed construction, including site plan and at
least one current boring if there is any reason to believe soil
conditions have been altered since the original soil testing. Large
systems designed for 1,200 gallon per day or more shall require a
hydro geologic investigation in accordance with Section 9-959(c).
(10)Conduct of Tests.All testing shall be conducted in accordance
with the requirements of this ordinance and shall be done by
qualified personnel, certified under the MPCA training and
certification program and licensed by the MPCA. All proposed
sites for sewage treatment systems shall be protected by fence or
other methods as necessary to avoid excavations, construction
equipment or other traffic that could affect the soil conditions.
(11)Soil Borings.
(a)Subdivision Testing.Enough borings must be done to
assure that suitable soils exist for each lot for long-term
sewage treatment. Percolation tests are not required
unless the permeability cannot be estimated, or there is any
reason to believe the soil is not original or has been
compacted.
(b)Permit Requirements.Complete testing on each individual
lot will be required prior to permit issuance independent of
any subdivision testing. A minimum of four (4) satisfactory
soil borings outlining an area of 5,000 square feet are
required. Larger areas may be required where conditions
of use, soils, topography, or vegetation require. Where soil
tests require a mound, testing and design must clearly
show suitable area for installation of two (2) complete
mounds.
(Where site conditions are such that the only backup
mound will likely be disturbed, the Department, at its
15
discretion, may require both mounds to be constructed at
once.)
(c)Soil borings shall be made as follows:
(1) Borings shall be by auger or excavation and shall be
staked and protected until notification that field
evaluation has been completed. Flite augers, which
are non-continuous or disturb extracted soil
samples, are not allowed. Borings shall be made to
a depth at least four (4) feet deeper than the bottom
of the proposed system or until bedrock or a water
table is encountered, whichever is less.
(2)Any evidence of disturbed or compacted soil must
be disclosed and may result in the prohibition of
utilizing that test area.
(3)Particular effort shall be made to determine the
highest known water table by recording the first
occurrence of mottling observed in the hole, or if
mottling is not encountered, the open holes in clay
or loam soils shall be observed after standing
undisturbed a minimum of 16 hours, and depth to
standing water, if present, shall be measured.
(d)A soil description shall be written for each soil observation at the
proposed site. Soils should only be evaluated under adequate
light conditions with the soil in a moist state and including the
following:
(1)The depth of each soil horizon measured from
the ground surface. Soil horizons are
differentiated by changes in soil structure, soil
texture, soil color, mottling, bedrock, or any
other characteristic that may affect water
percolation or treatment of effluent.
(2)The soil matrix and mottled color described
per horizon by the Munsell Soil Color Charts,
1992 Revised Edition, which is incorporated
by reference. This document is available from
Macbeth Division, Kollmorgen Instruments
Corporation, Munsell Color, P.O. Box 230,
Newburgh, New York 12551-0230.
16
It can be found at the Minnesota State Law
Library, Judicial Center, 25 Constitution
Avenue, Saint Paul, Minnesota 55155, and is
not subjectto frequent change;
(3)The soil texture described using the United
States Department of Agriculture (USDA) soil
classification system as modified below:
Minnesota USDA
Clay = Clay, sand clay, silty clay
Clay Loam = Clay loam, sandy clay loam, silty clay loam
Loam = Loam
Sandy loam = Sandy Loam
Silt loam = Silt loam, silt
Loamy sand = Loamy sand
Coarse sand = Coarse sand
(Medium) sand = (Medium) sand
Fine sand = Fine and very fine sand
(12)Percolation Tests.After soil borings have outlined the minimum area of
suitable soils, percolation tests shall be made as follows:
EXCEPTION:For sandy soils clearly in the 5 mpi range percolation
tests will not be required, however, the design rate for sizing shall be
1.27 square feet per gallon.
(a)Test hole dimensions and locations:
(1)Each test hole shall be six to eight inches in diameter, have
vertical sides, and be bored or dug to the depth of the
bottom of the proposed individual sewage treatment
system.
(2)Soil texture descriptions shall be recorded noting depths
where texture changes occur.
(b)Preparation of the test hole:
(1)The bottom and sides of the hole shall be carefully
scratched to remove any smearing and to provide a natural
soil surface into which water may penetrate.
17
(2)All loose material shall be removed from the bottom of the
test hole and two inches of one-fourth to three-fourths inch
gravel shall be added to protect the bottom from scouring.
(c)Soil saturation and swelling:
(1)The hole shall be carefully filled with clear water to a
minimum depth of 12 inches over the soil at the bottom of
the test hole andmaintained for no less than four hours.
Failure to adequately saturate the test hole may result in
rejection of the test.
(2)The soil shall then be allowed to swell for at least 16, but no
more than 30 hours. In sandy soils,the saturation and
swelling procedure shall not be required and the test may
proceed if one filling of the hole has seeped away in less
than ten minutes.
(d)Percolation rate measurement: In sandy soils adjust the water
depth to eight inches over the soil at the bottom of the test hole.
From a fixed reference point, the drop in water level shall be
measured in inches to the nearest one-eighth inch at
approximately ten-minute intervals. A measurement can also be
made by determining the time it takes for the water level to drop
one inch from an eight inch reference point. If eight inches of
water seeps away in less than ten minutes, a shorter interval
between measurements shall be used, but in no case shall the
water depth exceed eight inches. The testshall continue until
three consecutive percolation rate measurements vary by a range
of no more than ten percent.
In other soils, adjust the water depth to eight inches over the soil
at the bottom of the test hole. From a fixed reference point, the
drop in water level shall be measured in inches to the nearest
one-eighth inch at approximately 30-minute intervals, refilling
between measurements to maintain an eight-inch starting head.
The test shall continue until three consecutive percolation rate
measurements vary by a range of no more than ten percent.
The percolation rate can also be made by observing the time it
takes the water level to drop one inch from an eight inch reference
point if a constant water depth of at least eight inches has been
maintained for at least four hours prior to the measurement.
(e)Calculating the percolation rate. Divide the time interval by the
drop in water level to obtain the percolation rate in minutes per
18
inch. The slowest final percolation rate for all holes within the soil
treatment area shall be used for design.
(f)Frost. A percolation test shall not be run where frost exists below
the depth of the proposed soil treatment system.
(13) Construction and Materials.
(1)Building Sewers.
(A)Plumbing and Well Codes. The design, construction, and
location of, and the materials for use in building sewers are
governed bythe Minnesota State Building Code, chapter 1300,
which incorporates by reference portions of the Minnesota
Plumbing Code, chapter 4715, and by specific provisions of the
Minnesota Water Well Construction Code, Minn. Rules Chapter
4725.
(B)Water meter. All new individual sewage treatment systems
defined as mounds, alternative systems, or systems intended to
serve other establishments as defined in Section 9-952(d) (44)
must not be installed unless a water meter is provided to measure
the flow to the treatment system. For metered systems that have
septic tank effluent pumped to a soil treatment area, an electrical
event counter must also be installed.
(2)Sewage Tanks.
(A)In general. All tanks, regardless of material or method of
construction, must:
1)Be watertight;
2)Be designed and constructed to withstand all lateral
earth pressures under saturated soil conditions with
the tank empty, including proper ballasting (to avoid
possible flotation) where the severity of conditions
require it;
3)Be designed and constructed with adequate tensile
and compressive strength to withstand a minimum
of seven feet of saturated earth cover above the
tank top and manhole cover;
4)Not be subject to corrosion or decay; and
19
5)Have the manufacturer's name, model number, and
tank capacity in gallons permanently displayed on
the tank above the outlet pipe.
6)Have a written and graphic label affixed to the
maintenance hole cover warning of the hazardous
conditions inside the tank.
Any tank not having an integrally cast bottom shall not be
installed when the water table is closer than three inches to
the bottom of the excavation at the time of construction.
(B) Design of septic tanks. All tanks, regardless of material or
method of construction, shall conform to the following
criteria:
1)The liquid depth of any septic tank or compartment
thereof shall be not less than 30 inches. A liquid
depth greater than six and one-half feet shall not be
considered in determining tank capacity.
2)No tank or compartment thereof shall have an inside
horizontal dimension less than 24 inches.
3)Inlet and outlet connections of the tank shall be
submerged by means of baffles.
4)The space in the tank between the liquid surface
and the top of the inlet and outlet baffles shall be not
less than 20 percent of the total required liquid
capacity, except that in horizontal cylindrical tanks
this space shall be not less than 15 percent of the
total required liquid capacity.
5)Inlet and outlet baffles shall be constructed of acid
resistant concrete, acid resistant fiberglass, or
plastic.
6)Baffles must be integrally cast with the tank, affixed
with a permanent waterproof adhesive, or affixed
with stainless steel connectors,top and bottom.
Sanitary tees, which are used as baffles, shall be
affixed to the inlet or outlet pipes with a permanent
waterproof adhesive.
7)The inlet baffle shall extend at least six inches but
not more than 20 percent of the total liquid depth
20
below the liquid surface and at least one inch above
the crown of the inlet sewer.
8)The outlet baffle and the baffles between
compartments shall extend below the liquid surface
a distance equal to 40 percent of the liquid depth
except that the penetration of the indicated baffle or
sanitary tees for horizontal cylindrical tanks shall be
35 percent of the total liquid depth. They also shall
extend above the liquid surface as required herein.
In no case shall they extend less than six inches
above the liquid surface. Gas deflecting baffles
shall be installed on the outlet of the final septic tank
servicing other establishments.
9)There shall be at least one inch between the
underside of the top of the tank and the highest
point of the inlet and outlet devices.
10)The inlet invert shall be not less than two inches
above the outlet invert.
11)The inlet and outlet shall be located opposite each
other along the axis of maximum dimension. The
horizontal distance between the nearest points of the
inlet and outlet devices shall be at least four feet.
12)Sanitary tees, used as baffles, shall be at least four
(4) inches in diameter. Inlet baffles shall be no less
than six (6) inches or no more than 12 inches
measured from the end of the inlet pipe to the
nearest point on the baffle. Outlet baffles shall be
six inches measured from beginning of the outlet
pipe to the nearest point on the baffle.
13)Access to the septic tank shall be as follows:
a)There shall be one or more manholes, at a
minimum of 20 inches least dimension, and located
within six feet of all walls of the tank. Access to
tanks will be by manhole covers with no more than 6
inches of cover. If the cover is exposed it must be
secured to prevent unauthorized entry if it is
exposed.
b)There shall be an inspection pipe of at least
four inches diameter over both the inlet and outlet
21
devices. The inspection pipe shall extend through
the tank cover or the manhole cover and be capped
flush or above finished grade. A downward
projection of the centerline of the inspection pipe
shall be directly in line with the centerline of the inlet
or outlet device.
c)An inspection pipe at least four inches in
diameter must be located between the inlet and
outlet baffles for the purpose of evaluating scum and
sludge accumulations.
The inspection pipe must extend through either the
tank cover or manhole cover and must be capped
flush with or above finished grade.
14)Compartmentation of single tanks.
a)Septic tanks larger than 3,000 gallons and
fabricated as a single unit shall be divided into
two or more compartments.
b)When a septic tank is divided into two
compartments, not less than one-half or more
than two-thirds of the total volume shall be in
the first compartment.
c)When a septic tank is divided into three or
more compartments, one-half of the total
volume shall be in the first compartment and
the other half equally divided in the other
compartments.
d)Connections between compartments shall be
baffled so as to obtain effective retention of
scum and sludge. The submergence of the
inlet and outlet baffles of each compartment
shall be as specified herein.
e)Adequate venting shall be provided between
compartments by baffles or by an opening of
at least 50 square inches near the top of the
compartment wall.
f)Adequate access to each compartment shall
be provided by one or more manholes; at
least 20 inches least dimension, and located
22
within six feet of all walls of the tank. The
manhole shall extend through the tank cover
to a point within six (6) inches of finished
grade. If the manhole is covered with less
than sixinches of earth, the cover must be
secured to prevent unauthorized access.
15)Multiple tanks.
a)Where more than one tank is used to obtain
the required liquid volume, the tanks shall be
connected in series.
b)Each tank shall comply with all other
provisions of Section 9-953(d)(13)(1)(A).
c)No more than four tanks in series can be used
to obtain the required liquid volume.
d)The first tank shall be no smaller than any
subsequent tanks in series.
16)Outlet pipe from septic tank.
a)The outlet pipe from the septic tank must not
be cast iron.
b)The outlet pipe extending from the septic tank
must be of sound and durable construction,
not subject to corrosion or decay.
c)The outlet pipe extending from the septic tank
to the undisturbed soil beyond the tank must
meet the strength requirements of American
Society for Testing and Materials (ASTM),
schedule 40 plastic pipe and must be
supported in a manner that there is no
deflection during the backfilling and
subsequent settling of the soil between the
edge of the septic tank and the edge of the
excavation.
d)The soil around the pipe extending from the
septic tank must be compacted to original
density for a length of three feet beyond the
edge of thetank excavation.
23
9-953(e)(14)Capacity of Septic Tanks.Capacity of septic tanks:
(A)Dwellings. There shall be two septic tanks in series with
the liquid capacity based on the number of bedrooms contemplated in
the dwelling served and shall be at least as large as the capacities given
below.
EXCEPTION:Upgrade of existing conforming systems need not consist
of two (2) tanks in series assuming the primary tank capacity is met, and
there isno garbage disposal or sewage pump. System replacement
shall require two tanks in series.
Number of Tank Liquid
BedroomsCapacities (Gallons)
2 or less1,000 and 500
3 or 41,000 and 1,000
5 or 61,500 and 1,000
7, 8 or 92,000 and 1,000
For ten or more bedrooms, the septic tank shall be sized as another
establishment with the second tank in series being at least 50 percent
capacity of the first tank. For multiple family dwellings containing two (2) or
more dwelling units, the size shallbe the sum of the individual dwelling unit
requirements.
(B)Other establishments. The liquid capacity of a septic tank serving
an establishment other than a dwelling shall be sufficient to provide a
sewage detention period of not less than 36 hours in the tank for sewage
flows less than 1,500 gallons per day, but in no instance shall the liquid
capacity be less than 750 gallons. For sewage flows greater than 1,500
gallons per day the minimum liquid capacity shall equal 1,125 gallons plus
75 percent of the daily sewage flow. For restaurants and laundromats,
twice the liquid capacity shown above must be provided. For laundromats
the outlet baffle of the septic tank must be submerged to a depth of 50
percent.
(C)Pumping of raw sewage. A sewage pump must not deliver
sewage to a one-tank system if the pump cycledelivers more than one
percent of the liquid capacity of the tank. For systems with multiple tanks,
at least two tanks in series must be used, each having at least the liquid
capacity specified in this subpart. The volume of sewage delivered in each
24
pump cycle must not exceed five percent of the liquid capacity of the first
tank.
9-953(e)(15) Location of Septic Tanks.The sewage tank shall be placed so that it is
accessible for the removal of liquids and accumulated solids. The soil
cover over a tankshall not exceed five (5) feet.
The sewage tank shall be placed on firm and settled soil capable of
bearing the weight of the tank and its contents.
Sewage tanks shall be set back as specified in Section 9-953(2),
Table IV.
Sewage tanks shall not be placed in areas subject to flooding or in
floodplains, or in areas for which regional flood information is available
from the DNR.
9-953(e)(16)Abandoned Tanks.At any time tanks are taken out of service they shall
be removed from the ground or abandoned in place by properly removing
all contents, disconnecting all lines, and filling the tank completely with
soil. Access for future discharge to the system shall be permanently
denied.
9-953(e)(17)Aerobic Tanks.Aerobic tank treatment systems shall comply with the
general requirements for sewage tanks set forth in this ordinance, and
with the following:
(1)The treatment system including each individual unit or
compartment shall be easily accessible for inspection and
maintenance and shall be provided with secured covers.
(2)Aerobic tanks shall comply with National Sanitation Foundation
Standard (NSF) No. 40 (November 1990). Effluent quality shall
meet or exceed NSF Class II Standards.
(3)An effective maintenance service contract shallbe maintained for
the life of the unit and shall include inspections and effluent quality
checks at least semi-annually.
(4)No additional reduction in soil treatment area shall be allowed with
the use of an aerobic treatment tank.
9-953(e)(18)Distribution of Effluent.
(1)All supply pipes must be protected from freezing when they pass
under driveways, sidewalks, roadways or other areas where deep
frost penetration is expected.
25
(2)Gravity distribution.
(A)Serial distribution must be used to distribute effluent to
individual trenches in a soil treatment system unless the
necessary elevation differences between trenches for drop boxes
cannot be achieved by natural topography or by varying the
excavation depths, in which case parallel distribution shall be
used. If drop boxes are used, they must meet the following
standards.
1)The drop box shall be watertight and constructed of
durable materials not subject to corrosion or decay.
2)The invert of the inlet pipe shall be at least oneinch
higher than the invert of the outlet pipe to the next
trench.
3)The invert of the outlet pipe to the next trench shall
be no greater than two inches higher than the invert
of the outlet pipe of the trench in which the box is
located.
4)When sewage tank effluent is delivered to the drop
box by a pump, the pump discharge shall be
directed against a wall or side of the box on which
there is no outlet.
5)The drop box shall have a removable cover either
flush or above finished grade or covered by no more
than six inches of soil and must have a vertical
inspection pipe, capped flush with or above finished
grade.
(B)The distribution boxes must meet the following standards:
1)The box must be watertight with either a removable
coveror a clean out pipe extending to finished grade
and must be constructed of durable materials not
subject to corrosion or decay.
2)The inverts of all outlets must be at the same
elevation.
3)The inlet invert must be either at least one inch
above the outlet inverts or be sloped such that an
26
equivalent elevation above the outlet invert is
obtained within the last eight feet of the inlet pipe.
4)Each drain field trench line must be connected
separately to the distribution box and must notbe
subdivided.
5)When sewage tank effluent is delivered to the
distribution box by pump, either a baffle wall must
be installed in the distribution box or the pump
discharge must be directed against a wall or side of
the box on which there is no outlet. The baffle must
be secured to the box and must extend at least one
inch above the crown of the inlet flow line.
(C)Distribution pipes.
1)Distribution pipes used in trenches or beds for
gravity distribution must be at least four inches in
diameter and must be constructed of sound and
durable material not subject to corrosion or decay or
to loss of strength under continuously wet
conditions.
2)Perforated pipe used for sewage distribution pipes
must have one or more rows of holes of no less than
one-half inch in diameter spaced no more than 40
inches apart. Holes must be spaced to prevent
failure due to loads. Distribution pipes must have a
load bearing capacity of not less than 1,000 pounds
per lineal foot.
3)The distribution pipes for gravity distribution must be
laid level or on a uniform slope away from the
distribution device of no more than four inches per
100 feet.
4)Other devices such as corrugated tubing wrapped
with a permeable synthetic material or a chambered
trench or bed may be used to distribute sewage tank
effluent over the soil treatment area upon approval
of the department.
(3)Pressure distribution.
(A)Pressure distribution must be used for the following soil treatment
systems:
27
1)All mound systems;
2)All at-grade systems; and
3)Systems where the soil percolation rate is 0.1 to
five minutes per inch if the effluent is pumped to a
seepage bed or to trenches that are all at the same
elevation.
(B)Distribution pipes used for pressure distribution must be
constructed of sound and durable material not subject to corrosion
or decay or to loss of strength under continuously wet conditions.
(C)All pipes and associated fittings used for pressure distribution
must be properly joined together. The pipe and connections must
be able to withstand a pressure of at least 40 pounds per square
inch.
(D)Perforations must be no smaller than 3/16-inch diameter and no
larger than one-quarter inch diameter. The number of
perforations, perforation spacing, and pipe size for pressure
distribution laterals must be as shown in Table I. The friction loss
in any individual perforated lateral must not exceed 20 percent of
the average pressure head on the perforations.
28
Maximum Allowable Number of One-Fourth-Inch Diameter, or Smaller,
Perforations Per Lateral.
TABLE I
Pipe Diameter, Normal and Inside
Perforation1"1¼"1½"2"
Spacing in feet1.0491.3801.6102.067
2.58141828
38131726
3.37121625
47111523
56101422
(A)Perforation holes must be drilled straight into the pipe and not at
an angle. The perforated pipe laterals must be installed level with the
perforations downward. Perforation holes must be free of burrs.
(B)Laterals must be spaced no further than 60 inches apart and must
be spaced no further than a horizontal distance of 30 inches from the
bottom edge of a drain field rock layer.
(C)Laterals must be connected to a header or manifold pipe that is of
a diameter such that the friction loss in the header or manifold will be no
greater than five percent of the average head at the perforations. The
header or manifold pipe must beconnected to the supply pipe from the
pump.
(D)Perforated laterals must be designed and installed in such a way
that no perforations are located closer than 12 inches from the edge of the
drain field rock.
9-953(e)(19)Lift Station.
(1)Lift Station. A lift station, where used, shall meet the following
requirements:
(A)The lift station shall be watertight and constructed of sound and
durable materials not subject to excessive corrosion or decay, vented, and
29
must be designed and constructed to withstand lateral pressures when the
tank is empty.
(B)There shall be one or more maintenance holes, at least 20 inches
least dimension and located directly above the pump. The maintenance
hole shall extend through the lift station cover to final grade and shall be so
constructed as to prevent
unauthorized entry.
(C)The lift station shall either include an alternating two-pump system
or have a minimum total capacity of 500 gallons or 100 percent of the
average design flow, whichever is greater.
(D)A lift station must have an alarm device to warn of failure.
(E)Pumps shall be elevated from the bottom of the lift station to
protect the pump from settled solids. The pump, pump controls, and pump
discharge line shall be installed so as to be accessible for servicing without
entering the lift station.
(F)Electrical installations shall comply with applicable laws and
ordinances including the latest codes, rules, and regulations.
(2) Lift stations for gravity distribution:
(A)Where a lift station is employed, a pump or siphon shall deliver
the dose to the soil treatment unit for gravity distribution over the soil
treatment area.
(B)For dwellings, the dosing device shall discharge at least 600
gallons per hour but no more than 2,700 gallons per hour.
(C)For other establishments, the dosing device should discharge at a
rate at least ten percent greater than the water supply flow rate but no
faster than the rate at which effluent will flow out of the distribution device.
(D)If the dosing device is a siphon, a maintenance inspection shall be
made every six months by the owner or the owner's agent. The siphon
shall be maintained in proper operating condition.
(E)If the dosing device is a pump, it shall be cast iron or bronze fitted
and with stainless steel screws or constructed of other sound, durable, and
corrosion-resistant materials.
(F)Where the soil treatment area is at a higher elevation than the
pump, sufficient dynamic head shall be provided for both the elevation
difference and friction loss.
30
(G)Where the dosing device is a pump, an alarm device shall be
installed to warn of pump failure.
(3) Dosing devices for pressure distribution;
(A)The dosing device shall be a pump which is cast iron or bronze
fitted and with stainless steel screws or constructed of sound, durable, and
corrosion-resistant materials.
(B)The pump discharge capacity shall be based upon the perforation
discharges for an average head of 1.0 foot for residential systems and 2.0
feet for other establishments. Perforation discharge will be determined by
the following formula:
2
q = 19.65 cdh
where:
q = discharge in gallons per minute
c = 0.60 coefficient of discharge
d = perforation diameter in inches
h = head in feet
(C)The pump discharge head shall be at least five feet greater than
the head required to overcome pipe friction losses and the elevation
difference between the pump and the distribution device.
(D)The quantity of effluent delivered for each pump cycle shall be no
greater than 25 percent of one day's sewage flow.
(E)An alarm device shall be installed to warn of pump failure.
(F)A siphon will not be allowed as a lift station to deliver effluent to a
pressure distribution system.
9-953(e)(20)Final Treatment and Disposal.
(1)Final treatment and disposal of all sewage tank effluent shall be
by discharge into a soil treatment system.
(2)Standard system.
(A)Sizing:
1)The required soil treatment area shall be determined
by the daily sewage flow, and the measured percolation rate of
the soil.
31
2)Acceptable methods for estimating sewage flow for
dwellings are given in Table II. The minimum daily sewage flow
estimated for any dwelling shall provide for at least two bedrooms.
For multiple residential units, the estimated daily sewage flow
shall consist of the sum of the flows of each individual unit.
TABLE II
Number of Gallons per day
Bedrooms
2300
3450
4600
5750
6900
If a grey water system is employed, estimated sewage flow
equals 60 percent of the amount provided in Table II.
(1)For other establishments, average design flow shall be
used to size soil treatment systems. Maximum design flow
shall be used to size sewage tanks. Design flows shall be
calculated using estimated or measured values for other
establishments according to items a. and b.
a)Estimated average and maximum design flows: the
best available data as provided by the agency shall
be used if estimating the average and maximum
design flows.
b)Measured average and maximum design flows:
1. the average design flow shall be determined
by averaging the measured daily flows for a
consecutive seven-day period in which the
establishment is at maximum capacity or use;
and;
2.the maximum design flow shall
be the anticipated peak daily flow.
2)Table III (next page) gives the required trench bottom
area assuming 12 inches of drain field rock below the
distribution pipe. The required bottom area may be
32
reduced, for trenches only, by the following percentages:
20 percent for 18 inches of drain field rock below the
distribution pipe; and 34 percent for 24 inches. Unless
pressure distribution is used, all seepage bed bottom area
must be 1.7 times the soil treatment areas required in
Table III. With pressure distribution, the bottom area
must be 1.2 times the soil treatment area required in
Table III.
33
TABLE III
Percolation Rate0.1-6-1516-3031-4546-60
(minutes per inch)5
NUMBERTANK SIZEGALLONSSQUARE FEET
OF BEDROOMSPER DAY
21000 + 500 300250380500600660
31000 + 1000450380570750900990
41000 + 1000600500760100012001320
51500 + 1000750630950125015001650
61500 + 1000900750114150018001980
0
72000 + 10001050870133175021002310
0
82000 + 10001200990152200024002640
0
SQUARE FEET .831.271.6722.20
PER GALLON
34
TABLE III (continued)
Percolation Rate in
Soil TextureSquare Feet PerGallons Per Day
Minutes Per
Gallon Per DayPer Square Foot
Inch(MPI)
Faster than 0.1*Coarse Sand----------
0.1 to 5**Sand0.831.20
0.1 to 5Fine Sand***1.670.60
6 to 15Sandy Loam1.270.79
16 to 30Loam1.670.60
31 to 45Silt Loam2.000.50
46 to 60Clay Loam2.200.45
Slower than 60****Clay----------
See below for explanation of asterisks (*).
*Soil too coarse for sewage treatment.
**Distribution of sewage effluent shall be by pressure flow over the treatment area or
by dividing treatment area into a minimum of four (4) equal parts connected
serially, bymeans of drop boxes.
***For soils having more than 50 percent of very fine sand by weight, plus fine sand
having a particle size range of 0.05 millimeters (sieve size 270) to 0.25 millimeters
(sieve size 60), the required soil treatment area is 1.67 square feet per gallon of
sewage flow per day.
****Soil with too high a percentage of clay for installation of an in ground standard
system.
(A)Location:
1)On slopes in excess of 12 percent, the soil profile shall be carefully
evaluated in the locationof the proposed soil treatment system and down
slope to identify the presence of layers with different permeability’s that
may cause side hill seepage. In no case shall a trench be located within
15 feet of where such a layer surfaces on the down slope.
2)Bed construction shall be limited to areas having natural slopes of less
than six percent.
3)Soil treatment systems shall be located as specified on Table IV.
35
TABLE IV.
MINIMUM SETBACK DISTANCES (FEET)
SEWAGESOIL
FEATURETANKTREATMENT
AREA
Water Supply well less than 50 feet deep and not
encountering at least ten feet of impervious50100
material
Any other water supply well or buried water
suction pipe5050
Buried pipe distributing water under pressure1010
Occupied buildings & buildings with basements or crawl
spaces1020
Non-occupied structures55
Property lines10*10*
Above ground swimming pools1010
In ground swimming pools1020
THE ORDINARY HIGH WATER MARK OF:
LS-1 Natural Environment Lakes & Streams150**150**
LS-2 Recreation Development Lakes & Streams75**75**
LS-3 General Development Lakes & Streams75**75**
All unclassified waters75**75**
BLUFF LINES:
Shoreland Bluff lines (18% Slope)20**20**
*May be altered only through normal variance process.
**May be varied through Shoreland Management Ordinance.
4)Soil treatment areas shall not be placed in areas subject to flooding or in
floodplains or in areas for which regional flood information is available
from the DNR.
(B)Design and construction:
1)The bottom of trenches and beds shall be at least three feet above the
water table or bedrock.
2)The trenches shall be not less than 18 inches or more than 36 inches
shall be considered a bed.
wide. Any excavation wider than 36 inches
36
No bed may be wider than 25 feet and parallel beds must not be located
closer than ten feet apart.
3)The bottom of the trench or bed excavation shall be level.
4)The bottom and sides of the soil treatment system to the top of the drain
field rock shall be excavated in such a manner as to leave the soil in a
natural, un-smeared, and un-compacted condition. Excavation shall be
made only when the soil moisture content is at or less than the plastic
limit.
5)When the percolation rate is slower than 15 minutes per inch, excavation
shall be by backhoe or other means that allow the equipment wheels or
tracks to remain on the surface soil. Excavation equipment or other
vehicles shall not be driven on the soil treatment area.
6)There shall be a layer of at least 12 but no more than 24 inches of drain
field rock in the bottomof the trenches.
7)The drain field rock shall completely encase the top and sides of the
distribution pipes to a depth of at least two inches. The top of the drain
field rock in trenches, beds, and mounds must be level in all directions.
8)Drain field rock must be covered with a durable non-woven geotextile
cover specific to this purpose. The cover must be of sufficient strength to
undergo installation without rupture. In addition, the cover must permit
passage of water without allowing the passage of overlying soil material
into drain field rock.
9)The trenches or beds shall be backfilled and crowned above finished
grade to allow for settling. The top six inches of soil shall have the same
texture and density as the adjacent soil.
10)The minimum depth of cover over the distribution pipes shall be at least
six inches. The maximum depth of cover over the distribution pipes shall
be no more than 24 inches.
11)A vegetative cover shall be established over the soil treatment system.
The soil treatment system shall be protected until a vegetative cover is
established. The vegetative cover established shall not interfere with the
hydraulic performance of the system and shall provide adequate frost
and erosion protection.
12)A vertical inspection pipe at least 1-1/2 inches in diameter must be
installed in each drain field rock layer of every trench or seepage bed.
The inspection pipe must be located at an end opposite from where the
sewage tank effluent enters the rock layer. The inspection pipe must
37
have 3/8 inch or larger perforations spaced vertically no more than six
inches apart in the rock layer, and must be solid pipe above. The
inspection pipe must extend to the bottom of the rock layer and must be
capped flush with or above finished grade.
13)All joints for gravel-less drain field pipes or chambered systems must be
secured as recommended by the manufacturer.
14)Backfilling for gravel-less drain field pipe and chambered systems shall
not crush or damage the medium.
(C)Gravel-less drain field pipe. Gravel-less drain field pipe, including appurtenances,
shall be:
1)of commercially fabricated corrugated pipe completely encased by the
manufacturer in a geotextile wrap specific to this purpose;
2)an eight-inch or a ten-inchnominal ID pipe that meets the requirements
of American Society of Testing Materials (ASTM) F667, which is
incorporated by reference. The annual book of ASTM standards F667
"Standard Specification for Large Diameter Corrugated Polyethylene
Tubing and Fittings" was issued in 1985 and is available at ASTM, 1916
Race Street, Philadelphia, PA 19103. The standards can be found at the
Minnesota Law Library, Judicial Center, 25 Constitution Avenue, Saint
Paul, MN 55155, and are not subject to frequent change.
a)The pipes must be marked with an alignment stripe visible through
the geotextile wrap and installed with this stripe at top center.
b)The pipes shall contain a row or rows of cleanly cut three-eighths
inch to one-half inch diameter holes located in such a manner to
provide storage of solids. Each row shall contain a hole in every
other corrugation valley, staggered such that every corrugation
valley contains one hole.
3)Geotextile wraps specifically designed and tested for use with gravel-less
pipe and for installation and use in individual sewage treatment systems.
4)The sizing shall be 1.2 times the soil treatment area required in Table III.
5)Protected from heat and ultraviolet rays prior to installation.
(D)Chambered systems. Chamber media including all piping and appurtenances
shall be constructed:
38
1)of commercially fabricated materials specific to this purpose;
2)of materials resistant to sewage tank effluent;
3)with an open bottom;
4)to support the load of overburden and sidewall soil;
5)with slotted or perforated sides to allow sewage to move laterally into the
soil and prevent soil penetration into the chamber;
6)no greater than three (3) feet in width; and
7)with vertical outside dimensions less than 30 inches.
E)Dual field systems:
1)Dual field systems shall be used only where the percolation rate is slower
than five minutes per inch.
2)Dual field systems shall be sized, designed, and constructed as set forth
above for standard systems except as follows:
a)The soil treatment area shall be divided into two or more parts.
b)Alternating soil treatment areas shall each be connected to a
valve box outlet.
3)A part of the soil treatment area shall be used no more than one year
unless inspection of the effluent level indicates that a longer duration can
be used.
(2)Mounds.
(A)Mound Requirements
1)Mounds must be constructed on original soils so that there is at
least 36 inches of separation between the bottom of the drain field
rock layer and limiting soil characteristics as defined in Section 9-
952.
2)There must be at least 18 inches of original soil with a percolation
rate faster than 60 minutes per inch above the limiting soil
characteristics as defined in Section 9-952.
EXCEPTIONS For Previously Developed Sites:
39
a)A depth of 12 to 18 inches of original suitable soil may be
used.
b)A 61 to 120 minutes per inch rate may be used.
3)If original soil conditions do not exist on a site proposed for a
mound, as defined in Section 9-952, the site is unsuitable for a
mound.
4)Absorption areas shall not be placed in areas subject to flooding
as described in Section 9-955(d).
5)On slopes of one percent or greater, and where the percolation
rate in the top foot of original soil is in the 61 to 120 minutes per
inch range, mounds must not be located where the ground-
surface contour lines directly below the long axis of the rock bed
represent a swale or draw, unless the contour lines have a radius
of curvature greater than 100 feet. Mounds must never be located
in swales or draws where the radius of curvature of the contour
lines is less than 50 feet. In no case shall mounds be placed on
slopes greater than 12 percent.
(B)Design of mounds. Drain field rock must be used as the distribution medium in
mounds.
1)The bottom area of the rock bed shall be calculated by multiplying the
average design flow by 1.0 square feet per gallon per day.
2)The width of a single rock bed must not exceed ten feet.
3)A minimum of 12 inches of clean sand must be placed where the rock
bed is to be located.
4)The required absorption width is calculated by multiplying the rock bed
width by the absorption ratio. The absorption ratio shall be determined
according to Table V, using percolation rate of the upper 12 inches of soil
in the proposed absorption area.
5)A maximum of two (2) mounds may be placed with side-by-side rock
beds. The required absorption width shall be increased by four (4) feet.
40
TABLE V
Percolation Rate ofOriginal Soil
Under Sand Layer, Minutes Per Absorption Ratio
Inch
Faster than 51.00
6 to 151.50
16 to 302.00
31 to 452.40
46 to 602.67
61 to 1205.00
6)The required absorption width for mounds constructed on slopes from
zero to one percent shall be centered under the rock bed width. The
required absorption width for mounds constructed on slopes greater than
one percent shall be measured down slope from the down slope edge of
the rock bed width and measured in the direction of the original land
slope and perpendicular to the original contours.
7)The side slopes on the mound must not be steeper than three (3)
horizontal units to one (1) vertical unit and shall extend beyond the
required absorption area, if necessary.
8)On slopes of one (1) percent or greater, the upslope edge of the level
drain field rock bed must be placed on the contour.
9)Whenever mounds are located on slopes greater than one (1) percent, a
diversion must be constructed immediately upslope from the mound to
intercept and direct runoff.
10)Distribution of effluent over the rock bed must be by level perforated pipe
under pressure as specified in Section 9-953(18).
11)The rock bed shall completely encase the top and sides of the
distribution pipes to a depth of at least two (2) inches above the pipe.
The rock shall extend nine (9) inches below the pipe.
12)A vertical inspection pipe at least 1½-inches in diameter shall be installed
and secured at each rock bed/sand interface of every mound.
41
The inspection pipe must have 3/8 inch or larger perforations spaced
vertically no more than six (6) inches apart. At least two (2) perforations
must be located in the rock bed. No perforations shall be located above
the permeable synthetic fabric. The inspection pipe must extend to the
bottom of the rock bed and must be capped flush with or above finished
grade.
13)The rock bed must be covered with durable non-woven geotextile cover
specific to this purpose. The cover must be of sufficient strength to
undergo installation without rupture. In addition, the cover must permit
passage of water without passage ofoverlying soil material into the drain
field rock.
14)Sandy to loamy soil material must be placed on the rock bed to a depth
of one (1) foot in the center of the mound and to a depth of six (6) inches
at the sides. When two (2) rock beds are installedside by side, the soil
material must be 18 inches deep at the center of the mound and six (6)
inches deep at the sides.
15)Six (6) inches of topsoil must be placed over the entire mound. Topsoil
does not include peat soil textures.
(B)Surface preparation for mounds.
1)The supply pipe from the pump to the mound area must be installed
before mound soil surface preparation. The trench excavated for the
supply pipe must be carefully backfilled and compacted to prevent
seepage of effluent.
2)All vegetation in excess of two (2) inches in length and dead organic
debris must be removed from the absorption area. Trees must be cut
nearly flush with the ground and stumps should not be removed.
3)All surface preparation must take place when the upper 12 inches of soil
has a moisture content of less than the plastic limit and soil conditions
allow field testing of soil properties and these properties are maintained
throughout installation.
4)The absorption area must be roughened by backhoe teethor moldboard,
or chisel plowed to a depth of eight (8) inches. Discing is allowed if the
upper eight (8) inches of soil has a texture of sandy loam or coarser. If
plowed, furrows must be thrown uphill and there must not be a dead
furrow in the absorption area.
42
A rubber-tired tractor may be used for plowing or discing. Rototilling or
pulverizing the soil is not allowed. The original soil must not be
excavated or moved more than one foot from its original location during
soil surface preparation.
5)Before the placement of six (6) inches of clean sand, no vehicle shall be
driven on to the absorption area after the surface preparation is
completed.
If rainfall occurs on the prepared surface, the site must be allowed to dry
below the plastic limit androughened as specified above.
(C)Mound construction.
1)The clean sand must be placed by using a construction technique that
minimizes compaction. If the clean sand is driven on for construction, a
crawler or track-type tractor must be used for moundconstruction. At
least six (6) inches of sand must be kept beneath equipment to minimize
compaction of the prepared surface.
2)The sand layer upon which the rock bed is placed must be level in all
directions.
3)The top of the rock bed must be levelin all directions.
4)Construction vehicles must not be allowed on the rock bed until backfill is
placed.
5)A vegetative cover must be established over the entire area of the
mound. The soil treatment system mound shall be protected until a
vegetative cover is established. The vegetative cover established shall
not interfere with the hydraulic performance of the system and shall
provide adequate frost and erosion protection.
6)Shrubs must not be planted on the top of the mound. Shrubs may be
placed at the foot and side slopes of the mound.
(2)At-grade systems.
(A)Location of at-grade systems.
(1)At-grade systems must be constructed on original soils so that
there
is at least 36 inches of separation between the bottom of the rock
bed and saturated soil or bedrock.
(2)Percolation tests shall be conducted in the upper 12 inches of
43
original soil. At-grade systems are only allowed if constructed on
soils with percolation rates faster than 61 minutes per inch.
(3)At-grade systems shall not be installed in areas with slopes
greater
than 12 percent.
(B)Design of at-grade systems.
(1)Rock bed absorption width shall be calculated by multiplying the
linear loading rate by the soil sizing factor as identified in
9-953(d)(20) Table III, using the percolation rate of theupper 12
inches of soil in the proposed absorption area.
The linear loading rate shall be between two (2) and eight (8)
gpd/ft as determined by the relationship between vertical and
horizontal water movement in the soil. Total rock bed width for
sloping ground shall consist of the rock bed absorption width plus
enough rock on the upslope side to provide stability.
(2)Rock bed length shall be calculated by multiplying the soil-sizing
factor by the average design flow and dividing by the rock bed
width.
At-grade systems shall be pressurized in accordance with Section
9-
953(d)(18). Distribution pipe shall be installed in the center of the
rock bed on slopes less than one (1) percent and on the upslope
edge of the rock bed absorption width on slopes one (1) percent
or
greater.
(C)Construction of at-grade systems.
1)Surface preparation for at-grade systems shall be the same as mound
construction.
2)Drain field rock must be used as the distribution medium in at-grade
systems.
3)The upslope edge of an at-grade system shall be installed along the
natural contour.
4)The rock bed shall completely encase the top and sides of the
distribution pipe to a depth of at least two (2) inches above the pipe.
There shall be at least nine (9) inches of rock below the distribution pipe.
44
5)The entire rock bed shall be covered with a durable non-woven geotextile
cover specific to this purpose. The cover must be of sufficient strength to
undergo installation without rupture. In addition, the cover must permit
passage of water without allowing the passage of overlying soil material
into the drain field rock.
6)One foot of loamy or sandy cover material shall be installed over the rock
bed. Cover shall extend at least five (5) feet from the ends of the rock
bed and be sloped to divert surface water. Side slopes shall not be
steeper than four (4) horizontal units to one (1) vertical unit. The upper
six (6) inches of the loamy soil cover must be topsoil. Topsoil must be of
a quality that provides a good vegetative cover on the at-grade system
and must exclude peaty material.
7)Three (3) verticalinspection pipes of at least 1.5 inches in diameter shall
be installed and secured along the down slope portion of the rock bed.
These pipes shall be located within three (3) feet of the down slope edge
of the rock bed at the middle and one-sixth of the total rock bed length
and placed as measured from the ends of the rock bed. The inspection
pipes shall have 3/8 inch or larger perforations spaced vertically no more
than six (6) inches apart. No perforations shall exist above the
permeable synthetic fabric. The inspection pipes must extend to the rock
bed/soil interface and must be stabilized and capped flush with or above
finished grade.
8)A vegetative cover must be established over the entire area of the at-
grade system. The soil treatment at-grade system shall be protected
until a vegetative cover is established. The vegetative cover shall not
interfere with the hydraulic performance of the system and shall provide
adequate frost and erosion protection.
45
ALTERNATIVE AND EXPERIMENTAL SYSTEMS
9-954General.The intent of this part is to provide standards for the location, design,
installation, use, and maintenance of alternative and experimental sewage treatment
systems. Alternative systems must meet the requirements listed below and can only be
used when a standard system cannot be installed or is not the most suitable treatment.
They may be employed provided:
(a) reasonable assurance of performance of the system is presented to the
permitting authority;
(b) the engineering design of the system is first approved by the permitting
authority;
(c) there is no discharge to the ground surface or to surface waters. Systems
designed with a ground surface or surface water discharge are not covered under
this chapter and mustobtain a National Pollutant Discharge Elimination System
permit or state disposal system permit from the Minnesota Pollution Control
Agency;
(d) a three-foot minimum separation is provided between the bottom of the
distribution medium and the saturated soil or bedrock;
(e) treatment and disposal of wastes is completed in a manner that protects the
public health and general welfare;
(f) the system meets all local codes and ordinances and is subject to periodic
inspections by the permitting authority toassure adherence to specifications;
(g) provide a mitigative plan to the permitting authority, indicating what will be done
if the system fails to provide treatment and disposal; and
(h) provide a water meter (located down flow of any outside sill cocks) to verify
water use.
9-955 Floodplain Areas.
9-955(a)There shall be no pipe or other installed opening between the distribution
medium and the soil surface.
9-955(b)Trench systems shall be located on the highest feasible area of the lot and shall
have location preference over all other improvements except the water supply well. The
bottom of the distribution medium shall be at least as high as the elevation of the ten-year
flood. The sewage tank may be located so as to provide gravity flow to the trenches.
46
9-955(c)If a lift station is used to move effluent from the sewage tank to the trenches,
provisions shall be made to prevent the pump from operating when inundated with
floodwaters.
9-955(d)When it is necessary to raise the elevation of the soil treatment area, a mound
system as specified in Section 9-953(d)(20), may be used with the following additional
requirement: In no case shall the sand base fill for the mound exceed 48 inches below
the rock bed. The elevation of the mound shall be such that the elevation of the bottom
of the rock bed shall be at least one-half foot above the ten-year flood elevation.
Inspection pipes shall not be installed unless the top of the mound is above the elevation
of the regional flood.
9-955(e)When the topof a sewage tank is inundated, the dwelling must cease
discharging sewage into it. This may be accomplished by either temporarily evacuating
the structure until the system again becomes functional, or by diverting the sewage into a
holding tank as follows:
If a holding tank is used for a dwelling, its liquid capacity shall equal 100 gallons times the
number of bedrooms times the number of days between the ten-year stage on the rising
limb of the regional flood hydrograph and the ten-year stage on the falling limb of the
hydrograph, or 1,000 gallons, whichever is greater. For other establishments, storage
equal to at least five times the average design flow must be provided. The holding tank
must be accessible for removal of tank contents under flooded conditions.
9-955(f)The building sewer shall be designed to prevent backflow of liquid into the
building when the system is inundated. If a holding tank is used, the building sewer shall
be designed to permit rapid diversion of sewage into the holdingtank when the system is
inundated.
9-955(g)Whenever the water level has reached a stage above the top of a sewage tank,
the tank shall be pumped to remove all solids and liquids after the flood has receded
before use of the system is resumed.
9-956Greywater system.A toilet waste treatment device shall be used in conjunction
with a greywater system. In all cases, only toilet wastes shall be discharged to toilet
waste treatment devices. Greywateror garbage shall not be discharged to the device
except as specifically recommended by a manufacturer.
9-956(a) Plumbing.The drainage system in new dwellings or other establishments shall
be based on a pipe diameter of two inches to prevent installation of a water flush toilet.
There shall be no openings or connections to the drainage system, including floor drains,
larger than two inches in diameter. For repair or replacement of an existing system, the
existing drainage system may be used.
9-956(b) Building sewer.The building sewer shall meet all requirements of Section 9-
953(13)(1) except that the building sewer for a greywater system shall be no greater than
two inches in diameter.
47
9-956(d) Sewage tank.Greywater septic tanks shall meet all requirements of Section 9-
953(d)(13). The soil treatment area shall be 60 percent of the amount calculated in Table
III in Section 9-953(d)(20). The septic tank for a greywater system shall be a single tank
in accordance with the first tank shown in Section9-953(d)(14)(A).
9-956(d)Final treatment of greywater shall meet all requirements of Section
9-953(d)(20).
9-957 Other toilet waste treatment devices.
Other toilet waste treatment devices may be used where reasonable assurance of
performance is provided.
All devices shall be vented.
All electric, gas, and water connections shall conform to all local ordinances and codes.
Operation and maintenance shall follow the manufacturer's recommendations.
9-958Collector Systems.
9-958(a)Where site and soil conditions do not provide suitable conditions for final
treatment and disposal on an individual lot, a soil treatment system located on another lot
or lots may be employed where approved by the city council.
9-958(b)Collector systemsshall be designed by a registered Professional Engineer,
licensed in the State of Minnesota, and certified by the MPCA as competent in the field of
on-site system design.
9-958(c) Hydro-geologic Study -due to the effect large flows have on groundwater quality
and groundwater mounding, a hydrologist shall determine site suitability based on the
following issues:
(1)Identify the depth to the static groundwater level and any perched water or areas
likely to be seasonally saturated.
(2)Identify depth tobedrock.
(3)Identify the proposed depth of the distribution medium.
(4)Determine the direction of groundwater flow (both horizontally and vertically).
(5)Determine background groundwater quality at the location.
48
(6) Estimate the height of groundwater mounding from the proposed system to
confirm adequate vertical separation.
(7)Determine whether drinking water standards can be met at the property boundary.
(8)Estimate the impact of water quality on existing or future downstream wells.
Depending on this estimate, piezometer and or monitor wells may be required.
EXCEPTION:
Systems designed for 1,200 gallons per day or less do not require a hydro
geologic study, or a design by a registered professional engineer.
9-958(d)Application to the department shall be accompanied by the hydro-geologic study
and engineering drawings and specifications and shall demonstrate compliance with the
Zoning Ordinance, Plumbing Code and issues relating to joint ownership of land, joint
system maintenance responsibilities, homeowners associations, easements, covenants
and such other items as may apply to the specific proposal.
9-958(e)Design.
(1)The sum of a common soil treatment system shall be based on the sum of the
areas required for each dwelling unit or establishment being served.
(2)The system shall be designed with each residence having a sewage tank or with a
common sewage tank. The tank shall be sized according to Section 9-953(d)(13).
(3)Sewer systems shall be designed on an estimated average daily flow for dwellings
based on Table II, set forth in part 9-953(d)(20), plus estimated flows from other
establishments.
(4)The sewer for systems with common sewage tanks shall be so constructed to give
mean velocities, when flowing full, of not less than two feet per second. The
sewer for systems with individual sewage tanks shall be so constructed and
designed to hydraulically conduct the flow for which they were designed. In no
case shall a gravity sewer be less than four inches in diameter. The diameter and
grade line should be based on a flow equal to 50 percent of the average design
flow occurring in a one-hour period.
(5)Flows shall be increased to allow for 200 gallons of infiltration per inch of pipe
diameter per mile per day.
(6)Cleanouts, brought flush with or above finished grade, shall be provided wherever
a common sewer joins an individual building sewer or piping from an individual
sewer tank, or every 100 feet, whichever is less, unless manhole access is
provided.
49
(7)There shall be no physical connection between sewers and water supply systems.
Sewers shall be set back from water supply systems and piping as required for
building sewers. Where it is not possible to obtain proper separation distances,
the sewer connections shall be watertight and pressure tested.
(8)Pipes, pipe points and pump stations shall be watertight.
(9)Pump stations shall have manholes flush with or above finished grade for cleaning
and maintenance.
(10)Manhole covers shall be so constructed as to prevent unauthorized entry.
(11)Pumps and lift stations shall be sized to handle 50 percent of the average design
flow in a one-hour period. Common pump tanks shall have a pump out capacity of
ten percent of average design flow and two alternating pumps.
(12) An alarm system shall be provided for all pumping stations to warn of pump failure,
overflow, or other malfunction.
(13) For systems with individual septic tanks, a stilling tank of at least 1,500 gallons
liquid capacity or ten percent of the average design flow, whichever is greater,
should be provided before the soil treatment system.
(14)Maintenance. All persons using a common drain field system shall assure, by
contract with maintenance personnel or other equivalent means, that the system
will be adequately maintained throughout its useful life. The system so maintained
includes, but is not limited to, common drain fields, common sewage tanks,
common pumps, common pump stations, common sewers, and all individual tanks
connected to the common system.
50
9-959Sewage Holding Tanks.Sewage holding tanks may be considered for
installation on previously developed sites, as a temporary method for periods of up to one
(1) year, during which time measures are being taken to provide municipal sewer service
or the installation of an approved system as provided in this ordinance.
Holding tanks may be considered on a permanent basis for nonresidential, low water use
establishments generating less than one hundred fifty (150) gallons per day of waste,
subject to approval by the department and the issuance of a certificate of compliance.
Holding tanks may also be considered for floor drains for vehicle parking areas, and
existing facilities potentially generating a hazardous waste.
(a)Design and installation.
(1)A sewage-holding tank shall be constructed and installed as specified in
this Ordinance for sewage tanks.
(2)Holding tanks shall be located as required for sewage tanks, as in
Section 9-953(d) Table IV, and at locations readily accessible by normal
pumping equipment under all weather conditions.
(3)Holding tanks shall be provided with a clean-out pipe of six (6) inch
minimum diameter extending to or above the ground surface, capped or
sealed to prevent odors and inflow of surface water.
(4)Holding tanks shall be provided with a manhole of twenty (20) inch
minimum least dimension to within a minimum of six (6) inches below
finished grade. Covers shall be secured to prevent unauthorized entry.
(5)When installed in areas of high ground water, within six (6) feet of the
ground surface, holding tanks shall be installed entirely above the ground
water level or shall be installed according to an engineer's design to
prevent flotation.
(b) Capacity.
(1)Sewage holding tanks shall have a minimum capacity of one thousand
two hundred (1,200) gallons or four hundred (400) gallons times the
number of bedrooms for a dwelling unit, whichever is greater.
(2)For other establishments, capacity shall be based on measured or
estimated flow rates. Minimum capacity shall be equal to at least eight
(8) times the daily flow rate.
(3)Water use metering shall be required for each dwelling unit or other
establishment served by a holding tank.
(c) Service and maintenance.
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(1)Where holding tanks are installed, the owner shall provide and maintain
a contract with a licensed pumper, providing for regular pumping of the
tank.
(2)Records of pumping data, to include dates, quantities and septage
disposal location, shall be maintained by the pumping contractor and
reported quarterly to the permitting authority.
(3)Holding tanks shall be provided with alarm or warning devices that will
activate a signal when the tank reaches seventy-five (75) percent of its
capacity.
(4)The permitting authority shall be provided right of access to perform
periodic maintenance and operational inspections of the system.
9-960 Experimental Systems.Systems utilizing innovative techniques or methods may
be considered for new or existing development under the following conditions:
(a)Reasonable assurance of performance of the system is presented to the
permitting authority.
(b)System being proposed is substantiated by engineering data and approved by
the permitting authority.
(c)System is in compliance with Minnesota Pollution Control Agency rules.
(d) Adequate area for long-term sewage treatment by suitable soils as required for
standard systems is identified and reserved on the site.
(e) Performance monitoring of the system, including but not limited to water use
metering, effluent quality and system maintenance are provided.
(f) Failure of experimental system to function or to properly treat sewage to a
standard-equivalent to a standard drain field system will require discontinuation
of use until reasonable modifications can be made or the system is replaced
with a standard system.
(g) A mitigative plan must be provided to deal with possible system failure. It must
include the planned corrections and/or replacement, as well as a clear
agreement signed by all parties clarifying who will pay for the mitigation.
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SECTION 9-961. OPERATION AND MAINTENANCE
9-961 General Requirements.Each individual on-site sewage treatment system
currently existing as well as those installed under this ordinance shall be operated and
maintained according to the provisions of this section.
9-961(a)Maintenance of Septic Tanks.
(1)The owner of any septic tank or the owner's agent shall regularly, but in no
case less frequently than every three years, have the tank or tanks pumped.
As an alternative, the owner may have the tank or tanks professionally
inspected to measure the accumulations of sludge, which includes the settled
materials at the bottom of the tank, and the accumulations of scum, which
includes grease and other floating materials at the top of the tank. The owner
of any septic tank or the owner's agent must arrange forthe removal and
sanitary disposal of septage from the tank whenever the top of the sludge layer
is less than 12 inches below the bottom of the outlet baffle or whenever the
bottom of the scum layer is less than three inches above the bottom of the
outlet baffle. Removal of septage shall include complete removal of scum and
sludge. If the inspector determines that pumping the tank or tanks is not
necessary, then the inspector shall prepare documentation as to the condition
of the tank(s) and submit the report to the city.
(2) The owner or the owner's agent shall install access to the septic tanks in
accordance with Section 9-953(d)(13) to allow for proper maintenance.
(3) Individual sewage treatment system additives, which contain hazardous
materials, must not be used in individual sewage treatment systems in
Minnesota.
(4) Individual sewage treatment system additives must not be used as a means to
reduce the frequency of proper maintenance and removal of septage from the
septic tank as specified in item (1).
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9-961(b)Maintenance of System Components.Whenever inspection of pump
stations, distribution devices, valve or drop boxes indicates the accumulation of solids,
such device shall be promptly cleaned.
9-961(c) Activities on the Soil Treatment Area.Activities on the soil treatment area or
the alternate soil treatment area that may impair the treatment abilities or hydraulic
performance of the soil treatment system are prohibited.
(1) Any maintenance activity used to increase the acceptance of effluent to a soil
treatment system must:
(A)not be used on failing systems;
(B)not decrease the separation to the saturated soil or
bedrock;
(C)not cause preferential flow from the system bottom to
the saturated soil or bedrock; and
(D)be conducted by a qualified employee or under an
installer license.
9-961(d) Disposal of Septage.Septage shall be disposed of only by approved means
as follows:
(1) Septage shall be disposed in accordance with all state and federal
requirements.
(2) Septagemust be disposed into a municipal treatment system.
SECTION 9-962. ADMINISTRATION
9-962(a)Applicability.The ordinance shall apply and be in effect for the stated
purposes for the City of Maplewood.
9-962(b)Enforcement.
(1)The City of Maplewood shall be responsible for administration and
enforcement of this ordinance.
(2)The department or its agent shall be qualified and certified by the MPCA
as competent in the design, evaluation and inspection of individual on-
site sewage treatment systems.
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(3)If the Department finds that by reason of exceptional circumstances the
strict enforcement of any provisions of this ordinance would cause undue
hardship or that strict conformity with the standards would be
unreasonable, impractical, or not feasible under the circumstances, the
Department in its discretion may permit modifications in individual cases
upon conditions as it may prescribe for prevention, control, or abatement
of pollution in harmony with the general purpose of these standards and
the intent of applicable state and federal laws. In no case will the 36-inch
separation requirement be compromised.
9-962(c)Board of Adjustment and Appeals.
(1)The Maplewood City Council shall hear and decide appeals and review
any order, decision ordetermination made by the department about the
enforcement of this ordinance.
(2)An appeal of an administrative decision or determination may be filed by
any person, department, bureau, city, county, or state.
9-962(d)Permits Required.Permits shall be required for sewage treatment
system as follows:
(1)All new installations of sewage tanks, treatment systems and
components thereof.
(2)All repair, extension, replacement or modification of existing systems and
components.
(3)Any change in use of a facility served by an existing sewage treatment
system.
(4)Permits shall not be required for normal routine inspection and
maintenance of systems.
(5)No building permit shall be issued for any new construction until the
permit required for the treatment system has first been issued.
(6)No building permit shall be issued for remodeling involving 50 percent or
more of the structure, or alterations that would affect the water use, such
as bedrooms, bathrooms, or additions to living space (excluding such
things as screen porches, entryways, decks, attics, patios, uninhabitable
storage space, etc.) until the treatment system has been determined to
be both adequate and conforming, or the city has first issued a permit for
a new treatment system.
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(7)Where work requiring a permit under this ordinance has been
commenced without first having obtained a permit, work shall be ordered
to stop until the permit requirement has been satisfied.
9-962(e)Inspections Required.Inspection as required determining compliance
with this ordinance shall be performed by the department or its
authorized agent under the following circumstances:
(1)Site inspections to verify and evaluate soil and site conditions and to
determine suitability of soils and system design.
(2)Necessary investigation to determine compliance of existing systems at
the time of remodeling, alteration, or additions.
(3)Installation inspections shall be made at each installation, prior to any
work having been covered by backfill.
(A)The licensed installer shall be responsible to notify the department
a minimum of twenty-four (24) hours before the time the work is
ready for inspection or reinspection.
(B)Work that is backfilled prior to required inspection may be ordered
to be uncovered whenever necessary to determine compliance.
(C)When, upon inspection, any part of the system is determined not
to be in compliance with this ordinance, written notice shall be
provided by the department indicating the deficiency and the
required corrections.
(D)Noted deficiencies shall be properly corrected and reinspected
before any other work on the project is continued.
(E)No system shall be placed or replaced in service until final
inspection and approval of the installation.
(F)Contractor, upon completion of installation, shall file with the
department, as-built drawings indicating the location of system
components dimensioned from a permanent reference point.
(4)Mounds -A minimum of three construction inspections are required:
(A)When the original soil under the mound has been roughened, but
prior to placement of the sand fill. Enough of the proposed sand
fill must be present to be viewed.
(B)After placement of rock and piping but prior to cover.
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(C)Final inspection, when job is completed.
(5)The owner or occupant of a property shall be responsible to provide
access at reasonable times, to the department or its agent, for the purpose of
performing inspections required under this ordinance.
(6)To enforce this ordinance the department may enter a building, property,
or a place where there is reason to suspect a system is failing to properly
treat or dispose of sewage.
(7)Fees for inspections, reinspections, or other services rendered under this
ordinance shall be as set by resolution of the Maplewood City Council
from time to time.
SECTION 9-963. LICENSING AND PERMITS
9-963(a)Licensing.All persons, firms, or corporations proposing to engage in
the business of installation, constructing, pumping, soil testing, designing, or providing
private inspection or maintenance services for on-site sewage treatment systems shall be
registered and licensed by the Minnesota Pollution Control Agency.
9-963(b)Permits.No person, firm, or corporation shall install, alter, repair or
extend any individual sewage treatment system in the City of Maplewoodwithout first
having obtained a permit, from the department for the specific work, and having paid the
fee prescribed for such permit as determined from time to time by the Maplewood City
Council.
9-963(c)Permit Application.Permit application shall be made in writing upon
forms provided by the department and shall contain data including, but not limited to the
following:
(1)The correct address and legal description of the property where the
proposed work is to take place.
(2)Site plan, drawn to scale, showing the location of all proposed and
existing structures, property lines, water supply wells within 100 feet,
terrain features such as bluff lines, water bodies or water ways, buried
utilities, easements and other unique features of the site.
(3)Soil test data, including soil boring logs, percolation test data with field
notes, and the location and identification of test area.
(4)Plans and details of the proposed installation of work, including
engineering data and final design.
(5)In certain cases, a survey may be required showing all the above
information including such things as elevations, contour lines, normal
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high water marks, and ten (10) year and one hundred (100) year flood
elevations.
(6)Building plans showing existing and proposed roomarrangement and
uses.
(7)For other than dwellings, calculated or measured water use rates
occupancy and occupant load.
(8)Evidence of compliance with state or other jurisdiction regulations where
applicable.
9-963(d)Term of Permit.Permits shall be valid upon issuance, for a period of
one (1) year and may be renewed, when no changes are proposed, upon application for
renewal and payment of the fee prescribed.
9-963(e)Permit Revocation.Permits issued under this ordinance may be
revoked upon written notice of the department when such permit has been issued based
upon erroneous or inaccurate application data.
SECTION 9-964. ENFORCEMENT
9-964(a)Violations and Penalties.It is hereby declared unlawful for any person,
firm or corporation to violate any term or provision of this ordinance. Violation thereof
shall be a misdemeanor. Each day that a violation is allowed to continue shall constitute
a separate offense.
9-964(b)Enforcement.In the event of a violation or a threatened violation of this
ordinance, the department, in addition to other remedies, may request appropriate
actions or proceedings to prevent, restrain, correct, or abate such violations or threatened
violations. In addition, written notice in the form of a license complaint may be made to
the Commissioner of the Minnesota Pollution Control Agency (MPCA). If there is known
contamination of ground water, the city also may notify the Minnesota Department of
Health for a possible well advisory.
9-964(c)Public Health Act.In cases where a public health nuisance has been
determined to exist the Department may institute enforcement action under the Public
Health Act Section 145A.
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SECTION 9-965. EFFECTUATION
9-966(a)Separability.It is hereby declared to be the intent that the several
provisions of this ordinance are separable in accordance with the following:
(1)If any court of competent jurisdiction shall adjudgeany provision of this
ordinance to be invalid, such judgment shall not affect any other
provisions of this ordinance not specifically included in said judgment.
(2)If any court of competent jurisdiction shall adjudge invalid the application
of any portion of this ordinance to a particular property, building or other
structure, such judgment shall not affect the application of said provision
to any other property, building, or structure not specifically included in
said judgment.
This ordinance was passed by the City Council of the City of Maplewood, Minnesota on
th
January 282002.
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