[Ord. No. 11-0248 §1, 8-9-2011]
This code establishes construction standards for on-site sewage
treatment systems. In accordance with the authority granted in Section
701.040, RSMo., this code establishes the standards and criteria for
the design, location, installation and repair of individual on-site
sewage treatment systems to promote the public health and general
welfare and to protect the surface and ground waters of the State.
[Ord. No. 11-0248 §1, 8-9-2011; Ord.
No. 18-0499, 12-10-2018]
All on-site wastewater treatment and treatment systems shall
be located in accordance with the distances shown in Table 602.1.
Distances shall be measured from the point in the treatment system
closet to the property line, stream, lake, impoundment or well.
|
Table 602.1
Minimum Setback Distances
| |||
|---|---|---|---|
|
Minimum Distance From3
|
Tank1
(feet)
|
Treatment
Area2 (feet)
|
Lagoons6
(feet)
|
|
Private water supply well
|
50
|
100
|
100
|
|
Public water supply well
|
300
|
300
|
300
|
|
Cistern
|
25
|
25
|
25
|
|
Spring
|
50
|
100
|
100
|
|
Classified stream, lake or impoundment*
|
50
|
50
|
50
|
|
Stream or open ditch4
|
25
|
25
|
25
|
|
Property lines5
|
10
|
10**
|
100
|
|
Building foundation
|
15
|
15
|
100
|
|
Basement
|
15
|
25
|
100
|
|
Swimming pool
|
15
|
15
|
50
|
|
Water line under pressure
|
10
|
10
|
10
|
|
Suction water line
|
50
|
100
|
100
|
|
Upslope interceptor drains
|
-
|
10
|
10
|
|
Down slope interceptor drains
|
-
|
25
|
25
|
|
Top of slope of embankments or cuts of two (2) feet or more
vertical height
|
-
|
20
|
20
|
|
Edge of surficial sink holes
|
50
|
100
|
500
|
|
Other soil absorption system except repair area
|
-
|
20
|
20
|
|
*
|
A classified stream is any stream that maintains permanent flow
or permanent pools during drought periods and supports aquatic life.
|
|
**
|
Fifty (50) feet of downslope property line initially, but repair
may be allowed to twenty-five (25) feet of downslope property line.
|
|
1
|
Includes sewage tanks, intermittent sand filters and dosing
chambers.
|
|
2
|
Includes all systems (sand filter, wetland and the like) except
wastewater stabilization ponds.
|
|
3
|
Unplugged abandoned wells or wells with less than eighty (80)
feet casing depth shall have one hundred fifty (150) feet minimum
distance from all above.
|
|
4
|
Sewage tanks and soil absorption systems shall never be located
in the drainage area of a sinkhole.
|
|
5
|
The Code Official may grant minor variances to the property
line setbacks when the project involves installation of drip absorption
or trickle irrigation systems that are being installed to repair an
existing system on an existing lot that is otherwise too small to
maintain the regular setbacks. The Code Official must first determine
from data supplied by the licensed designer that under normal operating
conditions the effluent from the system will remain within the boundaries
of the property.
|
|
6
|
The lagoon shall be located a minimum of two hundred (200) feet
from the nearest existing adjoining residence.
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[Ord. No. 11-0248 §1, 8-9-2011; Ord. No. 13-0459 §2, 12-10-2013]
A.
Table
603.1(a) or 603.1(b) shall be used to determine the minimum design
daily flow of sewage required in calculating the design volume of
on-site sewage systems to serve selected types of establishments.
The minimum design volume of sewage from any establishment shall be
two hundred forty (240) gallons per day. Design of sewage treatment
and treatment systems for establishments not identified in this code
shall be determined using available flow data, water-using fixtures,
occupancy or operation patterns and other measured data.
1.
Volume determination. In determining the volume
of sewage from single-family dwellings, the minimum flow rate shall
be one hundred twenty (120) gallons per day per bedroom. The minimum
volume of sewage from each single-family dwelling shall be two hundred
forty (240) gallons per day. When the occupancy of a single-family
dwelling exceeds two (2) persons per bedroom, the volume of sewage
shall be determined by the maximum occupancy at a rate of sixty (60)
gallons per person per day.
[Ord. No. 18-0499, 12-10-2018]
2.
Other establishments. For establishments or housing
developments other than a single-family residence, either Table 603.1(a)
or Table 603.1(b) shall be used to estimate the sewage flow rate or
actual measured flow rate for existing systems may be used. Values
for estimated sewage flow for establishments having food service operations
shall be increased by a factor of one and one-half (1½) to
compensate for the high organic strength. Grease traps shall be required
at food service facilities, meat markets and other places of business
where the accumulation of grease or oils can cause premature failure
of a soil absorption system. The following design criteria shall be
met:
a.
The grease trap shall conform to Plumbing and Drainage Institute
Standard PDI-G101 or equivalent;
b.
The grease trap shall be plumbed to receive all wastes associated
with food handling and no toilet wastes;
c.
The grease trap liquid capacity shall be sufficient to provide for
at least five (5) gallons of storage per meal served per day, at least
two-thirds (⅔) of the required septic tank liquid capacity,
or a capacity as determined in accordance with the following formula:
|
LC = D x GL x ST x HR / 2 x LF
| ||||
|
Where:
|
LC
|
=
|
grease trap liquid capacity (gallons)
| |
|
|
D
|
=
|
number of seats in dining area
| |
|
|
GL
|
=
|
gallons of wastewater per meal
(1.5 single-service; 2.5 full-service)
| |
|
|
ST
|
=
|
storage capacity factor = 2.5
| |
|
|
HR
|
=
|
number of hours open
| |
|
|
LF
|
=
|
loading factor = (1.25 interstate highway
| |
|
|
=
|
1.0 other highways and recreational areas
| ||
|
|
=
|
0.8 secondary roads);
| ||
d.
Two (2) or more chambers must be provided, with total length-to-width
ratio at least two (2) to one (1). Chamber opening and outlet sanitary
tee must extend down at least fifty percent (50%) of the liquid depth;
e.
Access manholes, with a minimum diameter of twenty-four (24) inches,
shall be provided over each chamber and sanitary tee. The access manholes
shall extend at least to finished grade and be designed and maintained
to prevent surface water infiltration. The manholes shall also have
readily removable covers to facilitate inspection and grease removal;
and
f.
Where it has been demonstrated that specially designed grease interceptors
will provide improved performance, the grease trap liquid capacity
may be reduced by up to fifty percent (50%).
3.
Population to be served. Unless satisfactory justification
can be given for using lower per-unit occupancies, the figures in
Table 603.1(b) shall be used in determining the population for which
to design the sewage works.
4.
Reduction in sewage flow. Reductions in design sewage
flow rates may be allowed by the Code Official on a case-by-case basis
depending upon water conservation plans. Sewage flow rates may be
reduced up to forty percent (40%) for gray water systems where the
toilet wastes are discharged to a holding tank and disposed of off
site or where waterless toilets are utilized.
|
Table 603.1(a)
Quantities of Domestic Sewage Flows
[Ord. No. 13-0459 §2, 12-10-2013]
| ||
|---|---|---|
|
Type of Establishment1
|
Flow (gallons per day per unit unless otherwise
indicated)
| |
|
Residential Units
| ||
|
Single-Family Dwelling
|
120/bedroom
| |
|
Multiple-Family Dwelling (with laundry capabilities)
|
120/bedroom
| |
|
Multiple-Family Dwelling (without laundry)
|
95/bedroom
| |
|
Capabilities cottages
|
50/person (in excess of 2 persons/bedroom)
| |
|
Manufactured Home Parks
|
300/home 2
| |
|
Commercial Facilities
| ||
|
Transportation terminals (airports, bus stops, railroad stations,
etc.)
|
5/passenger
| |
|
Laundromats
|
580/machine
| |
|
Beauty Shops (Style Shops)
|
125/chair
| |
|
Bowling Lanes
|
50/lane
| |
|
Business (other than those listed elsewhere in this table)
|
25/employee
| |
|
Factories (exclusive of industrial waste)
|
25/person/shift
| |
|
With showers
|
10/person/shift
| |
|
Marinas
|
10/boat slip
| |
|
With bathhouse
|
30/boat slip
| |
|
Motels/Hotels
|
120/room
| |
|
With cooking facilities
|
175/person
| |
|
Offices (per shift)
|
25/person
| |
|
Service Stations
|
250/water closet or urinal
| |
|
24-hour Service Stations
|
325/water closet
| |
|
Theaters: Movies
|
5/seat
| |
|
Drive-in
|
15/vehicle space
| |
|
Warehouses
|
30/employee
| |
|
Public parks (toilets only)
|
5/user
| |
|
Public parks with bathhouse
|
15 — 25/user
| |
|
Camps
| ||
|
Construction or Work Camps
|
60/person
| |
|
With chemical toilets
|
40/person
| |
|
Summer Camps
|
60/person
| |
|
Campgrounds/Recreational Vehicle Park (without water and sewer
hookups)
|
100/campsites
| |
|
Campgrounds/Recreational Vehicle Park (with water and sewer
hookups)
|
120/space
| |
|
Assembly & Mercantile
| ||
|
Retail
|
120/1,000 sq. ft. of retail sales area
| |
|
Stadium, Auditorium, Theater, Drive-in
|
5/seat or space
| |
|
Swimming Pools, Spas, and Bathhouses
|
10/person
| |
|
Churches (not including a Kitchen, Food Service Facility, Day
Care or Camp)
|
3/seat
| |
|
Churches (with a Kitchen but not including Food Service Facility,
Day Care or Camp)
|
5/seat
| |
|
Food or Drink Establishment3
| ||
|
Food Service Facility, Day Care, Camp, or Country Club
|
20/member
| |
|
Bar (not serving food)
|
20/seat
| |
|
Restaurants
|
40/seat, or 40/15 sq. ft. of dining area whichever is greater
| |
|
24-hour Restaurant
|
75/seat
| |
|
Convenience Store
| ||
|
<2,000 sq. ft. floor space
|
500 gal/day
| |
|
With food preparation
|
750 gal/day
| |
|
2,000 — 3,000 sq. ft. floor space
|
750 gal/day
| |
|
With food preparation
|
1,125 gal/day
| |
|
3,000 — 5,000 sq. ft. floor space
|
1,000 gal/day
| |
|
With food preparation
|
1,500 gal/day
| |
|
5,000 — 7,000 sq. ft. floor space
|
2,000 gal/day
| |
|
With food preparation
|
3,000 gal/day
| |
|
>7,500 sq. ft. floor space
|
3,000 gal/day
| |
|
With food preparation
|
Under DNR regulation
| |
|
Food Stands
| ||
|
1) Per 100 square feet of food stand floor space
|
50 gal.
| |
|
2) Add per food employee
|
25 gal.
| |
|
Other food service facilities
|
5/meal
| |
|
Meat Markets
| ||
|
1) Per 100 square feet of market floor space
|
50 gal.
| |
|
2) Add per market employee
|
25 gal.
| |
|
Institutional3
| ||
|
Hospitals
|
300/bed
| |
|
Day Care Facilities
|
15/person
| |
|
Residential Care Facilities
|
60/person
| |
|
Rest Homes and Nursing Homes
| ||
|
With laundry
|
120/bed
| |
|
Without laundry
|
60/bed
| |
|
Day Schools
| ||
|
With cafeteria, gym, and showers
|
15/student
| |
|
With cafeteria only
|
12/student
| |
|
With neither cafeteria nor showers
|
10/student
| |
|
Boarding Schools
|
60/person
| |
|
1
|
Establishments with flows greater than three thousand gallons
per day (3,000 gpd) shall be regulated under Chapter 644, RSMo., administered
by the Department of Natural Resources.
| |
|
2
|
Shall consider flow into the soil absorption system from manufactured
homes where taps are allowed to run to prevent freezing.
| |
|
3
|
Establishments processing food may be required to provide grease
interceptors in an accessible location prior to the sewage treatment
system.
| |
|
Table 603.1(b)
Sewage Works Population/Design
| ||
|---|---|---|
|
Unit
|
Persons/Unit
| |
|
Apartments or Condominiums
| ||
|
(1 bedroom)
(2 bedroom)
(3 bedroom)
|
2.0
3.0
3.7
| |
|
Camper trailers with sewer hookup
|
3.0
| |
|
Camper trailers without sewer hookup
|
2.5
| |
|
Manufactured Homes
|
3.0 — 3.7
| |
|
Motels
|
3.0
| |
|
Residences
|
3.7
| |
|
Note: Gallons per person per unit includes normal infiltration
for residential systems.
| ||
[Ord. No. 11-0248 §1, 8-9-2011]
A.
All proposed sites for on-site sewage treatment systems shall be evaluated as set forth in Article IV.
B.
Soil Permeability. Soil permeability is that quality that
enables soil to transmit water or air. It can be measured quantitatively
in terms of flow of water through a unit cross section of saturated
soil in unit time under specified temperature and hydraulic condition.
C.
Soil Morphology. This evaluation shall be conducted by a
licensed on-site soil evaluator unless an engineer or registered geologist
has had special training and field experience that meets the requirements
of this code.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
Building Sewers. Building sewers used to conduct wastewater
from a building to an on-site wastewater treatment and treatment system
shall be constructed of material meeting the minimum requirements
of American Society for Testing and Materials (ASTM) Standards and
listed by that agency for such use. Suitable materials meeting ASTM
standards include: Acrylonitrile, butadiene styrene (ABS), cast-iron
pipe, concrete pipe, copper or copper-alloy tubing, polyvinyl chloride
(PVC) or vitrified clay pipe. Although listed by ASTM, asbestos cement
pipe is prohibited. Building sewer specifications are as follows:
1.
Size. Building sewers shall not be less than four
(4) inches in diameter;
2.
Slope. Building sewers shall be laid on a minimum
slope of twelve (12) inches per one hundred (100) feet.
3.
Cleanouts. A cleanout shall be provided at least
every one hundred (100) feet and at every change in direction or slope
if the change exceeds forty-five degrees (45°). A cleanout shall
be provided between house and tank.
4.
Connection to sewage tank. The pipe going into and
out of the sewage tank shall be schedule 40 PVC or cast iron and shall
extend a minimum of five (5) feet beyond the hole of excavation for
the sewage tank.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
General. All liquid waste and gray water with the following
exceptions shall discharge into the sewage tank. Roof, garage, footing,
surface water, drainage, cooling water discharges and hazardous wastes
shall be excluded from the sewage tank. Backwash from water softeners
and swimming pool filtration systems shall be excluded from the sewage
tank. In such event of excluding swimming pool filter backwash, the
Department of Natural Resources shall be contacted for applicability
of a discharge permit. All sewage tank effluent shall be discharged
to a soil absorption system that is designed to retain the effluent
upon the property from which it originated. All tanks regardless of
material or method of construction shall:
B.
Septic Tanks. Regardless of material or method of construction,
septic tanks shall conform to the following criteria:
1.
The liquid depth of any septic tank or its compartment shall be not
less than thirty-six (36) inches. A liquid depth greater than six
and one-half (6½) feet shall not be considered in determining
tank capacity.
2.
No tank or compartment shall have an inside horizontal dimension
less than twenty-four (24) inches.
3.
Inlet and outlet connections of the tank shall be protected by baffles or sanitary tees as defined in Subsection (B)(6).
4.
The space in the tank between the liquid surface and the top of the
inlet and outlet baffles shall not be less than twenty percent (20%)
of the total required capacity, except that in horizontal cylindrical
tanks, this space shall be not less than fifteen percent (15%) of
the total required liquid capacity.
5.
Inlet and outlet baffles shall be constructed of acid-resistant concrete,
acid-resistant fiberglass or plastic.
6.
Sanitary tees shall be affixed to the inlet or outlet pipes with
a permanent water-proof adhesive. Baffles shall be integrally cast
with the tank, affixed with a permanent water-proof adhesive or with
stainless steel connectors top and bottom.
7.
The inlet baffle shall extend at least six (6) inches but no more
than twenty percent (20%) of the total liquid depth below the liquid
surface and at least one (1) 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 forty percent (40%) of
the liquid depth, except that the penetration of the indicated baffles
or sanitary tees for horizontal cylindrical tanks shall be thirty-five
percent (35%) of the total liquid depth. They also shall extend above
the liquid surface as required in this code. In no case shall they
extend less than six (6) inches above the liquid surface.
9.
Approved filters shall be provided for outlets for each tank. Approval
shall be based on acceptable test data that confirms the filter reduces
Total Suspended Solids (TSS) a minimum average of forty percent (40%)
over conventional tees or baffles.
10.
There shall be at least one (1) inch between the underside of the
top of the tank and the highest point of the inlet and outlet devices.
11.
The inlet shall be not less than three (3) inches above the outlet.
12.
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 (4)
feet.
13.
Sanitary tees shall be at least four (4) inches in diameter. Inlet
baffles shall be no less than six (6) inches or no more than twelve
(12) inches measured from the end of the inlet pipe to the nearest
point on the baffle. Outlet baffles shall be six (6) inches measured
from beginning of the outlet pipe to the nearest point on the baffle.
14.
Access to the septic tank shall be as follows:
a.
Manholes. Access shall be provided over both the
inlet and outlet devices and to each tank compartment by means of
either a removable cover or a manhole. Where the top of the tank is
located more than eighteen (18) inches below the finished grade, manholes
and inspection holes shall extend to approximately six (6) inches
above the finished grade. The extension can be made using a riser
of approved material and fitted with tight covers of heavy metal or
concrete. Proper attention shall be given to the accident hazard involved
when manholes are extended close to the ground surface. All manhole
openings shall be provided with a substantial, fitted, water-tight
cover of concrete, cast iron or other approved materials. The manhole
covers shall have either an effective locking device or otherwise
be adequately sealed in a manner to prevent accidental access.
b.
A six (6) inch inspection port shall be provided over the inlet and
outlet baffles of each tank and terminate at or above grade. An inspection
port shall not be used as a pump out access. A manhole cover may also
serve in place of inspection ports.
15.
Compartmentation of single tanks shall be in accordance with the
following:
a.
Septic tanks, fabricated as a single unit, shall be divided into
two (2) or more compartments.
b.
When a septic tank is divided into two (2) compartments, not less
than one-half (½) nor more than two-thirds (⅔) of the
total volume shall be in the first (1st) compartment.
c.
When a septic tank is divided into three (3) or more compartments,
one-half (½) of the total volume shall be in the first (1st)
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 in Section 705.350 (B)(7) and (8) of this code.
e.
Adequate venting shall be provided between compartments by baffles
or by an opening of at least fifty (50) square inches near the top
of the compartment wall; and
f.
Adequate access to each compartment shall be provided by one (1)
or more manholes, with a minimum opening twenty (20) inches square
or in diameter and located within six (6) inches of all walls of the
tank.
16.
The use of multiple tanks shall conform to all of the following:
a.
Where more than one (1) 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 this Section.
c.
No more than three (3) tanks in series can be used to obtain the
required liquid volume.
d.
The first (1st) tank shall be no smaller than any subsequent tanks
in series.
17.
Septic tanks serving non-residential flows shall be a minimum of
one thousand (1,000) gallons liquid capacity and shall be at least
as large as the capacities given in Table 607.2(a). No tank shall
be designed to retain less than two (2) days, forty-eight (48) hours
flow.
|
Table 607.2(a)
Non-Residential Septic Tank Capacity
| ||
|---|---|---|
|
FLOW
(gallons per day)
|
MINIMUM LIQUID CAPACITY
(gallons)
| |
|
1 — 249
|
1,000
| |
|
250 — 374
|
1,250
| |
|
375 — 499
|
1,500
| |
|
500 — 649
|
1,800
| |
|
650 — 749
|
2,000
| |
|
750 — 849
|
2,200
| |
|
850 — 999
|
2,500
| |
|
1,000 — 1,249
|
3,000
| |
|
1,250 — 1,499
|
3,500
| |
|
1,500 — 1,749
|
4,000
| |
|
1,750 — 1,999
|
4,500
| |
|
2,000 — 2,249
|
5,000
| |
|
2,250 — 2,499
|
5,500
| |
|
2,500 — 2,749
|
6,000
| |
|
2,750 — 3,000
|
6,500
| |
18.
The liquid capacity of a septic tank serving a dwelling shall be
based upon the number of bedrooms contemplated in the dwelling served
and shall be at least as large as the capacities given in Table 607.2(b).
|
Table 607.2(b)
Residential Septic Tank Capacity*
[Ord. 12-10-2013 §2, 12-10-2013]
| ||
|---|---|---|
|
Number of Bedrooms
|
Minimum Liquid Capacity
(gallons)
| |
|
1 — 3
|
1,000
| |
|
4
|
1,250
| |
|
5
|
1,500
| |
|
6
|
1,750
| |
|
7
|
2,000
| |
|
8
|
2,250
| |
|
* These figures provide for use of garbage grinders, automatic
clothes washers and other household appliances (water usage not to
exceed 120 gallons per day per bedroom).
| ||
C.
Location. Location of the sewage tank shall be as follows:
1.
The sewage tank shall be placed so that it is accessible for the
removal of liquids and accumulated solids;
2.
The sewage tank shall be placed on firm and settled soil capable
of bearing the weight of the tank and its contents; and
3.
The sewage tank shall be set back as specified in Table 602.1.
D.
Solids Removal. The owner of any septic tank or his/her
agent shall regularly inspect and arrange for the removal and sanitary
treatment of seepage from the tank whenever the top of the sludge
layer is less than twelve (12) inches below the bottom of the outlet
baffle, or whenever the bottom of the scum layer is less than three
(3) inches above the bottom of the outlet baffle. Tanks shall be pumped
whenever the bottom of the scum layer is within three (3) inches of
the bottom of the outlet device or the sludge level is within twelve
(12) inches of the bottom of the outlet device.
E.
Tank Replacement. Septic tanks shall no longer be permitted
for tank replacement on existing systems unless a soil morphology
test is performed detailing the soil application rate is five tenths
(0.5) or better, or a NSF Class 1 aerator must be installed. A septic
tank can be used preceding a lagoon and as a trash tank preceding
a NSF Class 1 aerator. Existing septic tanks must be inspected by
a licensed design engineer or licensed installer to verify the tank
is sealed and has sufficient structural integrity. Tank replacement
will require a permit, drawings or plans that detail the proposed
tank location.
[Ord. No. 18-0499, 12-10-2018]
[Ord. No. 11-0248 §1, 8-9-2011]
A.
An aeration treatment unit (ATU) utilizes the principle of oxidation in the decomposition of sewage by the introduction of air into the sewage. An ATU may be used as the primary treatment unit instead of a septic tank except where special local conditions may limit their use. All ATU systems shall comply with the general requirements for sewage tanks set forth in Section 705.350(B) of this code and with the following:
1.
Limitations. Special conditions where Aeration Treatment
Units (ATUs) cannot be used may include, but not be limited to, intermittent
use (interruptions allowing more than five (5) days without continuous
flow) will adversely affect the functioning of the plant.
2.
General. The ATU shall be located where it is readily
accessible for inspection and maintenance. Setback distances for ATUs
shall be in accordance with Table 602.1.
3.
Design. All ATUs shall comply with National Standard Foundation NSF International Standard Number 40 or 245. In addition, all ATUs shall comply with the requirements stipulated in Section 705.260, Tanks. The ATU shall have a minimum treatment capacity of one hundred twenty (120) gallons per bedroom per day or five hundred (500) gallons, whichever is greater.
[Ord. No. 13-0459 §2, 12-10-2013]
4.
Effluent treatment. Effluent from an ATU shall be discharged into a soil absorption system or other final treatment system in accordance with Section 705.420. No reductions in the area of soil absorption systems or other final treatment systems shall be permitted.
5.
Operation and maintenance. Where ATUs are used,
operation and maintenance are required. ATUs shall be inspected at
least two (2) times each year, and pumped in accordance with manufacturer's
instructions. Operating permit from Jefferson County is required.
a.
Maintenance. The Code Commission shall be and is
hereby authorized to grant certification to the manufacturers of NSF
Class 1 aeration treatment units found to be listed with NSF International.
(1)
Criteria for approval. Constructions-installation
permits may be issued for on-site systems incorporating ATUs for single-family
dwellings and commercial facilities if the following criteria are
met:
(a)
The Code Commission has listed the ATU, including brand and
model or type where applicable, for use in on-site systems.
(b)
The ATU meets the performance and model selection criteria specified
for the proposed use.
(c)
The owner of the property served by the on-site system incorporating
the ATU has a written service contract as required in Section 705.360(5)(a)(14).
(2)
Listing and delisting.
(a)
Any person may submit an application for listing an ATU. The
application shall include:
(i)
Documentation that the ATU meets the performance requirements
in Section 705.360(5)(a)(3).
(ii)
Documentation that the ATU has been certified
by NSF International as a Class 1 and is still in good standing.
(iii)
A guide for inspecting the ATU installation.
(iv)
A plan for training agents on inspection of the
ATU and training and certifying system installers on installation
of the ATU.
(v)
A plan for training and certifying CMP on system maintenance
for the ATU.
(vi)
Documentation that the ATU complies with Section
705.360(5)(a)(5 — 7), (9).
(b)
The Code Official will approve applications to list ATU that the Code Official determines meet the performance requirements in Subsection (5)(a)(3) under normal operating conditions. ATU will be listed by brand and model or type for the treatment standards they achieve.
(3)
Performance testing and standards for listing ATUs.
(a)
Product testing. ATUs shall be tested according
to the product standards and testing protocol established by the NSF
International Standard Number 40 and 245 Residential Wastewater Treatment
System, July 2009 or another NSF International protocol approved by
the Code Official. Testing for the fecal coliform and total nitrogen
parameter shall include the collection and analysis of influent and
effluent grab samples at a minimum frequency of three (3) days per
week and the same duration (twenty-six (26) consecutive weeks) and
hydraulic loadings (design and stress loading) as the NSF International
sample collection requirements for the BOD5, CBOD5, and TSS parameters. The testing shall
be performed by NSF International or a testing facility acceptable
to NSF International.
(b)
Product performance. An ATU shall produce effluent
quality equal to or better than Treatment Standard I or II specified
in this Section:
(i)
Treatment Stand I means (NSF Standard 40):
i)
CBOD5 — The thirty
(30) day average of CBOD5 concentrations of
effluent samples shall not exceed twenty-five (25) mg/l. The seven
(7) day average of CBOD5 concentrations of
effluent samples shall not exceed forty (40) mg/l.
ii)
TSS — The thirty (30) day average of TSS
concentrations of effluent shall not exceed thirty (30) mg/l. The
seven (7) day average of TSS concentrations of effluent shall not
exceed forty-five (45) mg/l.
iii)
pH — The pH of individual effluent samples
shall be between six (6.0) and nine (9.0).
(ii)
Treatment Standard II means (NSF Standard 245):
i)
CBOD5 — The average
CBOD5 of all effluent samples shall not exceed
twenty-five (25) mg/l.
ii)
TSS — The average TSS of all effluent samples
shall not exceed thirty (30) mg/l.
iii)
Total Nitrogen — The average total nitrogen
concentration of all effluent samples shall be less than fifty percent
(50%) of the average total nitrogen concentrations of all influent
samples.
iv)
pH — The pH individual effluent samples shall
be between six (6.0) and nine (9.0).
(4)
ATU model type and size selection. The model,
type, and size of the ATU proposed for a system shall be consistent
with manufacturer recommendations and match the daily design wastewater
flow anticipated from the dwelling or facility.
(5)
Access ports. At a minimum, the ATU shall have
ground-level access ports sized and located to facilitate installation,
removal, sampling, examination, maintenance, and servicing of components
or compartments that require routine maintenance, or inspection. Access
ports shall facilitate:
(a)
Visually inspecting and removing mechanical or electrical components;
(b)
Removing components that require periodic cleaning or replacement;
(c)
Visual inspecting and collecting samples; and
(d)
Removing (manual/or pumping) accumulated residuals.
(e)
Access ports shall be protected against unauthorized
intrusion. Acceptable protective measures include, but are not limited
to, padlocks or covers that can be easily removed only with tools,
or a cover having a minimum net weight of 65 pounds.
[Ord. No. 13-0459 §2, 12-10-2013]
(6)
Malfunction, failure sensing, and signaling equipment.
(a)
The system shall be designed to prevent the passage of untreated
waste into the absorption field if the ATU malfunctions.
(c)
The ATU shall possess a mechanism or process capable of notifying
the system owner of failures. The mechanism shall have circuits separated
from pump circuits and deliver a visible and audible signal.
(i)
The visual alarm signal shall be conspicuous at a distance of
fifty (50) feet from the system and its appurtenances.
(ii)
The audible alarm signal strength shall be between
seventy (70) and ninety (90) dbA at five (5) feet and sixty (60) dbA
at a distance of eighteen (18) feet from the system and its appurtenances.
(iii)
The visual and auditory signals shall continue
to function in the event of electrical, mechanical equipment, or hydraulic
malfunction of the system. The audible signal may be disabled for
service while cause for the alarm is identified and alleviated.
(d)
A clearly visible label or plate with instructions for obtaining
service shall be permanently located near the failure signal.
(7)
Data plate. The ATU shall have permanent and
legible data plates as follows:
(a)
Located on the front of the electrical control, if the ATU has
an electrical control box or panel; and the tank, aeration equipment
assembly, or riser at a location accessed during maintenance cycles
and inspections.
(8)
Siting and absorption area construction criteria.
[Ord. No. 13-0459 §2, 12-10-2013]
(a)
ATU approved for Treatment Standard 40 may be sited and sized
as follows:
(i)
In areas with temporary water table, in accordance with specification
for sand filters in areas with temporary ground water.
(ii)
In areas with permanent ground water, where four
(4) feet of separation can be maintained between the bottom of the
trench and ground water and the other criteria in this code can be
met.
(iii)
On sites meeting criteria for standard on-site
systems or for pressurized systems in this code.
(b)
ATU used in conjunction with approved disinfection and approved
nitrogen reduction processes and approved for Treatment Standard 245
may be sited and sized as follows:
(9)
Limited warranty. The ATU manufacturer shall:
(10)
Installation. ATUs shall be installed in accordance
with the manufacturer's instructions and this code. The installer
shall be certified by the ATU manufacturer to install the system and
provide written certification to the Code Official that the ATU components
were installed in accordance with the manufacturer's instructions
and this code.
(11)
(Reserved)
(12)
Operation and maintenance standards. The owner of an ATU system must ensure the ATU and all components of the on-site system are properly operated and timely maintained or decommissioned and the effluent standards in Subsection (5)(a)(3) of this Section are met.
(13)
Owner's manual. The designer of each on-site
system using an ATU must provide a comprehensive owner's manual prepared
by the manufacturer or designer to the system owner, manufacturer's
representative, installer, and if requested, the Code Official before
or at the time of installation. The manual may be a collection of
individual system component manuals and shall include information
on system specifications, system installation, operating and maintenance,
and troubleshooting and repair.
(14)
Service contracts.
(a)
The owner of an ATU system must maintain a contract with a maintenance
provider certified by the manufacturer to serve and maintain the on-site
system. A service contract must be entered before the system is installed
and must be maintained until the system is decommissioned. A single
service contract and maintenance provider for both the ATU and other
components is preferable to multiple contracts for maintenance providers.
(b)
The service contract must provide the following:
(i)
Provide for a minimum of four (4) inspections and
service visits by a maintenance provider scheduled every one hundred
eighty (180) days over the two (2) year period to inspect, adjust,
and service the ATU;
(ii)
Provide for an ATU effluent quality inspection
by a maintenance provider consisting of, but not limited to, a visual
assessment for color, turbidity, and scum overflow; and olfactory
assessment for odors; and any other performance assessment or operational
diagnosis, which may include sampling of treated effluent (post-disinfection
if disinfection is used) necessary to determine or ensure proper operation
of the system;
(iii)
Include a clause stating that the dealer, authorized
representative, or maintenance provider must notify the system owner
in writing about any improper system function that cannot be remedied
during the time of inspection and include an estimated date of correction;
(v)
Details of service to be provided, including the
service required in this Section;
(vi)
Schedule of maintenance provider duties;
(vii)
Cost and length of service contract and time
period covered;
(viii)
Details of any warranty; and
(ix)
Owner's responsibilities under the contract for
routine operation of the on-site system.
(15)
Maintenance providers. Dealers or authorized
representative under a contract required in this Section must comply
with the following requirements.
(a)
A maintenance provider must observe and record conditions found
and report those observations to the system owner. System owner must
report evidence of any system failures to the Code Official and take
appropriate action approved by the Code Official to correct the problem.
Any repair or alteration must comply with this code.
(b)
Maintenance providers must maintain accurate records of their
service contracts, customers, performance data, and time line for
renewing the contracts. These records must be available for inspection
upon request by the Code Official.
(c)
Within thirty (30) days of their termination or expiration,
providers must notify the Code Official of service contract that are
terminated or not renewed.
(d)
All maintenance providers must make emergency service available
within forty-eight (48) hours of a service request.
(e)
The maintenance provider must submit six (6) month service reports
to the Code Official for each system under contract to be serviced
by the maintenance provider.
(f)
Anyone doing service on ATU must be certified by the manufacturer
and listed with NSF International.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
When
required as a design feature of an on-site sewage treatment system,
effluent pumps, associated equipment and connections shall comply
with the following:
1.
The pump must be rated for effluent service by the manufacturer and
meet electrical safety standards of Underwriters Laboratories or equivalent.
2.
The pump must be submersible and kept submersed at all times when
in use and the pump intake be kept a minimum of two (2) inches off
the tank bottom.
3.
The pump manufacturer shall provide a two (2) year limited warranty.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
Each
septic tank system shall have an effluent filter approved by the Code
Official.
1.
The person who installs the septic tank system shall install the
effluent filter as a part of the septic tank system in accordance
with the specifications provided by the manufacturer of the effluent
filter. An effluent filter shall:
2.
The access device shall provide access to each compartment of a septic
tank for inspection and maintenance either by means of an opening
in the top of the septic tank or by a riser assembly and shall include
an appropriate cover. The access device shall:
[Ord. No. 11-0248 §1, 8-9-2011; Ord. No. 13-0459 §2, 12-10-2013]
Electrical circuits to the ATU and PHT shall be provided with
manual circuit disconnects within a water-tight, corrosion-resistant,
outside enclosure (NEMA 4 X or equivalent) adjacent to the ATU and
PHT securely mounted at least twelve (12) inches above the finished
grade or inside of access port. Control panels provided by the manufacturer
shall be installed in a water-tight, corrosion-resistant enclosure
(NEMA 4 X or equivalent) adjacent to the unit or on the side of the
system readily visible from the unit and accessible by maintenance
personnel. Conductors shall be conveyed to the disconnect enclosure
and control panel through water-proof, gas-proof and corrosion-resistant
conduits. Splices and wire junctions, if needed, shall be made outside
the ATU and PHT in a water-tight, corrosion-resistant enclosure (NEMA
4 X or equivalent) securely mounted adjacent to the unit at least
twelve (12) inches above the finished grade. Wire grips, duct seal,
or other suitable material shall be used to seal around wire and wire
conduit openings inside the ATU and PHT and disconnect enclosure.
The ATU and PHT shall have an alarm device or devices to warn the
user or operator of a unit malfunction or a high water condition.
The alarm shall be audible and visible by system users and securely
mounted adjacent to the ATU and PHT, on the side of the system in
clear view of the unit, or inside the finished occupied space of the
system. If mounted outside, the alarm shall meet NEMA 4 X standards
or equivalent. The alarm circuit or circuits shall be supplied ahead
of any ATU and PHT electrical control circuit overload and short circuit
protective devices.
[Ord. No. 11-0248 §1, 8-9-2011]
The common design of absorption systems is the use of absorption
trenches, each separate from the other and each containing a distribution
pipe. This type system shall be used whenever practical. Other types
of absorption systems may be used as alternatives where the site conditions
meet the specific design requirements of the alternative systems.
Installation shall not be made while the soil is wet or moist. This
is to prevent smearing and destroying the structure of the soil. All
absorption systems shall have curtain drains, terraces or use of other
flow diversion methods to minimize surface or ground water from loading
the absorption field.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
The
absorption trench gives additional treatment to the sewage from the
treatment tank. Regardless of its appearance of clarity or transparency,
the outflow or effluent from a sewage tank is a dangerous source of
contamination. The satisfactory operation of the sewage treatment
system is largely dependent upon the proper site selection, design
and construction of the absorption trench.
1.
Gravity conventional absorption trenches shall not be constructed
in soils having a loading rate slower than three-tenths (0.3) gpd/square
foot and in no case shall gravity absorption trenches be constructed
in soil with loading rate faster than one and two-tenths (1.2) gpd/square
foot that may result in contamination of water bearing formations
of surface water.
2.
The absorption trench shall be located on the property to maximize
the vertical separation distance from the bottom of the absorption
trench to the seasonal high ground water level, as determined by the
presence of mottling, bedrock or other limiting layer. The vertical
separation between the bottom of the absorption trench and limiting
layer or seasonal high water table shall be no less than two (2) feet
for standard systems. Greater vertical separation may be required
where water-bearing formations are in danger of contamination.
3.
Absorption trenches shall not be constructed in unstabilized fill
or ground, which has become severely compacted due to construction
equipment.
4.
The loading rates in any absorption trench system shall be in accordance
with Table 613.15(a). Absorption trenches in highly permeable soils
shall have a minimum vertical separation of four (4) feet between
the absorption trench bottom and seasonal high ground water table
or bedrock. Cherty clays may have a loading rate of three-tenths (0.3)
gpd per square foot to eight-tenths (0.8) gpd per square foot. Cherty
clay soils located in areas of severe geological limitations shall
have less than fifty percent (50%) rock fragments and a vertical separation
distance of four (4) feet or more between the absorption trench bottom
and bedrock. Unlined absorption trenches shall not be installed in
cherty clays when the field evaluation indicated the presence of large
voids. Regardless of the loading rate, absorption trenches installed
in areas of severe geological limitations with cherty clays shall
be designed for a maximum loading rate of four-tenths (0.40) gallons
per square foot or a minimum three hundred seventy-five (375) square
feet per bedroom. The design loading rate shall be based on the most
hydraulically limiting naturally occurring soil horizon to a depth
of two (2) feet below trench bottom.
[Ord. No. 13-0459 §2, 12-10-2013]
|
Table 613.15(a)
Application Rate by Soil Groups for Conventional Systems
[Ord. No. 13-0459 §2, 12-10-2013]
| ||||
|---|---|---|---|---|
|
Soil Group
|
Soil Texture Classes
(USDA Classification)
|
Application Rate*
(gpd./sq. ft.)
| ||
|
Type
|
Texture
|
Structure/Color
| ||
|
I
|
Sands (with S or PS structure and clay mineralogy)
|
Sand, Loamy sand
|
Any striation/Brown (no gray)
|
1.2 — 0.8
|
|
II
|
Coarse Loams
(with S or PS structure and clay mineralogy)
|
Sandy loam, Loam
|
Granular, fine and medium subangular blocky
|
0.9 — 0.7
|
|
Sandy loam, Loam
|
Prismatic; coarse, subangular, and angular blocky
|
0.7 — 0.5
| ||
|
III
|
Fine Loams
(with S or PS structure and clay mineralogy)
|
Silt loam, Clay Loam, Sandy clay loam, Silty clay loam
|
Granular, fine, and medium subangular blocky
|
0.6 — 0.4
|
|
Silt loam, Clay loam, Sandy clay loam, Silty clay loam
|
Prismatic, coarse subangular and angular blocky
|
0.4 — 0.3
| ||
|
IV(a)
|
Clays
(with S or PS structure and clay mineralogy)
|
Sandy clay, Silty clay, Clay (low to moderate shrink/swell)
|
Granular, fine, and medium subangular blocky
|
0.4 — 0.2
|
|
Sandy clay, Clay, Silty clay, (low to moderate shrink/swell)
|
Prismatic; coarse subangular or angular blocky
|
0.3 — 0.1
| ||
|
*
|
Gallons of sewage tank effluent per day per square foot of trench
bottom (gpd/sq.ft.).
|
|---|---|
|
Note:
| |
|
I.
|
When loading rate is less than 0.4 gpd per square foot, backfill
above infiltration barrier shall be sand, loamy sand or sandy loam,
when available. Two (2) to four (4) inches of loamy soil shall be
used to cap the sandy backfill. This is to keep rainwater from entering
the system.
|
|
II.
|
The design loading rate shall be based on the most hydraulically
limiting naturally occurring soil horizon to a depth of two (2) feet
below trench bottom.
|
|
III.
|
Soil Groups I and II with loading rate 1.2 to 0.8 gpd per square
foot shall be required to have an aeration treatment unit (ATU) NSF
STD 40 or STD 245 for effluent discharge into an absorption system.
|
5.
Each absorption trench system shall have a minimum of three (3) trenches
with no one (1) trench longer than one hundred (100) feet unless approved
by the Code Official on a case-by-case basis. The absorption trenches
shall be located not less than three (3) times the trench width on
centers with a minimum spacing of five (5) feet on centers.
6.
Absorption trenches shall be at least eighteen (18) inches wide and
no more than thirty-six (36) inches wide. Thirty-six (36) inch wide
trenches shall not be utilized in soils with loading rates less than
four-tenths (0.40) gallons per square foot. The bottom of standard
absorption trenches shall be at least eighteen (18) inches and no
more than thirty (30) inches below the finished grade except as approved
by the Code Official.
7.
The pipe used between the sewage tank and the absorption system shall be a minimum of four (4) inch inside diameter equivalent to the pipe used for the building sewer as set forth in Section 705.340 of this code. The pipe shall have a minimum fall of not less than one-eighth (⅛) inch per foot. All joints shall be of water-tight construction.
8.
Gravity-fed absorption field distribution lines shall be at least
four (4) inches in diameter. Perforated distribution line shall have
holes at least one-half (½) inch and no more than three-fourths
(¾) inch in diameter.
a.
Pipe used for distribution lines shall meet the appropriate ASTM
standard or those of an equivalent testing laboratory. Fittings used
in the absorption field shall be compatible with the materials used
in the distribution lines.
b.
When four (4) inch or six (6) inch diameter corrugated plastic tubing
is used for distribution lines, it shall be certified as complying
with applicable ASTM standards. The corrugated tubing shall have either
two (2) or three (3) rows of holes, each hole between one-half (½)
inch and three-fourths (¾) inch in diameter and spaced longitudinally
approximately four (4) inches on centers. Coiled tubing shall not
be used.
9.
The absorption trenches shall be constructed as level as possible,
but in no case shall the fall in a single trench bottom exceed one-fourth
(1/4) inch in ten (10) feet. The ends of distribution lines shall
be capped or plugged, or when they are at equal elevations, they shall
be connected.
10.
Rock used in soil absorption systems shall be clean gravel, and graded
or sized between one and one-half (1½) and three (3) inches
with no more than ten percent (10%) material to pass through a one-half
(½) inch screen. The rock shall be placed a minimum of eighteen
(18) inches deep with at least twelve (12) inches below the pipe and
two (2) inches over the pipe and distributed uniformly across the
trench bottom and over the pipe. Limestone and dolomite shall be prohibited.
Before placing soil backfill over the trenches, the gravel shall be
covered with one (1) of the following:
11.
Complex slope patterns and slopes dissected by gullies shall not
be considered for installation of absorption trenches. Uniform slopes
under fifteen percent (15%) shall be considered suitable slope for
installation of absorption trenches. When slopes are less than two
percent (2%), provisions shall be made to insure adequate surface
drainage. When slopes are greater than four percent (4%), the absorption
trenches shall follow the contour of the ground. Uniform slopes between
fifteen percent (15%) and thirty percent (30%) shall not be used for
installation of absorption trenches unless the soils are three (3)
feet or more below the trench bottom. Slopes within this range may
require installation of interceptor drains upslope from the soil absorption
system to remove all excess water that might be moving laterally through
the soil during wet periods. Usable areas larger than minimum are
ordinarily required in this slope range. Slopes greater than thirty
percent (30%) shall not be utilized for installation of absorption
trenches unless the following requirements can be met and approval
is obtained from the Code Official:
a.
The slope can be terraced or otherwise graded or the absorption trenches
can be located in naturally occurring soil, so as to maintain a minimum
ten (10) foot horizontal distance from the absorption trench and the
top edge of the fill embankment; and
b.
The soil is permeable and no restrictive layers or water tables occur
at a depth within two (2) feet of the trench bottom; and
c.
Surface water runoff is diverted around the absorption trench field
so that there will be no scouring or erosion of the soil over the
field or to allow surface runoff onto the field; and
d.
If necessary, ground water flow from heavy rainfall is intercepted
and diverted to prevent that water from running into or saturating
the soil absorption system; and
e.
There is sufficient ground area available to install the absorption
trench system with these modifications.
f.
Grading design to be required on sewer site plan.
12.
Effluent distribution devices, including distribution boxes, flow
dividers and flow diversion devices, shall be of sound construction,
accessible without excavation, water-tight, not subject to excessive
corrosion and of adequate design as approved by the Code Official.
Effluent distribution devices shall be separated from the sewage tank
by a minimum of two (2) feet of undisturbed or compacted soil and
shall be placed level on a solid foundation of soil, gravel or concrete
to prevent differential settlement of the device. Distribution boxes
provided with flow equalizers are required.
a.
Each distribution line shall connect individually to the distribution
box and shall be water-tight.
b.
The pipe connecting the distribution box to the distribution line
shall be of a water-tight construction laid on undisturbed earth.
c.
No more than four (4) distribution lines shall be connected to a
distribution box receiving gravity flow unless the ground surface
elevation of the lowest trench is above the flow line elevation of
the distribution box.
13.
Step-downs or drop boxes may be used where topography prohibits the
placement of absorption trenches on level grade. Serial distribution
systems shall be limited to a separation of at least three (3) feet
between the bottom of the absorption trenches and the limiting condition
such as slow permeability or zone of seasonal saturation as evidenced
by mottling. Whenever the design sewage flow rate requires more than
seven hundred fifty (750) lineal feet of distribution line in a step-down
or drop-box type system, the absorption field shall be divided into
two (2) or more equal portions. Step-downs shall be constructed of
two (2) feet of undisturbed soil, constructed to a height level with
the top of the upper distribution line. The inlet to a trench shall
be placed either in the center or as far as practical from the outlet
(overflow) from the same trench. Drop boxes shall be constructed so
that the inlet supply pipe is one (1) inch above the invert of the
outlet supply pipe which is connected to the next lower drop box.
The top of the trench outlet laterals, which allow effluent to move
to the distribution lines, shall be two (2) inches below the invert
of the outlet supply line. It is required that drop boxes be designed
to close off the trench outlets to provide for periods of resting
when the absorption trench becomes saturated.
14.
Dosing or even distribution shall be provided on all systems when
the design sewage flow requires more than five hundred (500) lineal
feet of distribution line. When the design sewage flow requires more
than one thousand (1,000) lineal feet of distribution line, the absorption
field shall be divided into two (2) equal portions and each half dosed
alternatively, not more than four (4) times per day. Each side of
the system shall be dosed not more than four (4) times per day. The
volume of each dose shall be the greater of the daily sewage volume
divided by the daily dosing frequency, or an amount equal to approximately
three-fourths (¾) of the internal volume of the distribution
lines being dosed (approximately one-half (½) gallon per lineal
foot of four (4) inch pipe). Whenever dosed distribution box systems
are utilized, the separation distance between the absorption trench
bottom and limiting condition shall be at least two (2) feet.
15.
Gravelless subsurface absorption systems may be used as an alternative
to conventional four (4) inch pipe placed in gravel filled trenches;
however, they cannot be used in areas where conventional systems would
not be allowed due to poor permeability, high ground water or insufficient
depth to bedrock. Design approval for these systems is required from
the Code Official prior to installation and all manufacturing specifications
and installation procedures shall be closely adhered to. Gravelless
trench systems using fabric wrapped tubing shall not be used, where
wastes contain high amounts of grease and oil, such as in restaurants.
a.
Large diameter pipe. Pipe shall consist of eight
(8) inches, ten (10) inches corrugated polyethylene tubing encased
in a nylon, polyester, or nylon/polyester blend filter wrap installed
in a trench twenty-four (24) inches wide and backfilled with soil
classified as Soil Group I or II. The loading rate shall not exceed
eight-tenths (0.8) gallons per day per square foot.
(1)
The eight (8) inch to ten (10) inch corrugated polyethylene
tubing used in gravelless systems shall meet the requirements of ASTM
F667, Standard Specification for Large Diameter Corrugated Polyethylene
Tubing. For purpose of calculation, the eight (8) inch pipe may be
considered equal to eighteen (18) inches in width of a standard absorption
trench. The ten (10) inch pipe may be considered equal to twenty-five
(25) inches in width of a standard absorption trench.
(2)
Two (2) rows of perforations shall be provided located one hundred
twenty degrees (120°) apart along the bottom half of the tubing,
each sixty degrees (60°) away from each row of holes. Perforations
shall be cleanly cut and uniformly spaced along the length of the
tubing and shall be staggered so that there is only one (1) hole in
each corrugation. The tubing shall be marked with a visible top location
indicator. All gravelless drainfield pipe shall be encased at the
point of manufacture with a filter wrap of spun bonded nylon, spun
laced nylon, polyester, or nylon/polyester blend nylon filter wrap
or other substantially equivalent material approved by the Code Official.
Corrugated tubing shall be covered with black polyethylene sleeve,
which shall encase the large diameter pipe and wrap until just prior
to installation in the trench.
(3)
Rigid corrugated tubing shall be covered with filter wrap at
the factory and each joint shall be immediately encased in a protective
wrap that will prevent ultraviolet light penetration which shall continue
to encase the large diameter pipe and wrap until just prior to installation
in the trench. Filter wrap encasing the tubing shall not be exposed
to sunlight (ultraviolet radiation) for extended periods. Rocks and
large soil clumps shall be removed from backfill material prior to
being used. Clayey soils (Soil Group IV) shall not be used for backfill.
The near end of the large diameter pipe shall have an offset adapter
(small end opening at top) suitable for receiving the pipe from the
treatment unit or distribution device and making a mechanical joint
in the trench.
(4)
The trench for the gravelless system shall be dug with a level
bottom. On sloping ground, the trench shall follow the contour of
the ground to maintain a level trench bottom and to ensure a minimum
backfill of six (6) inches. It is recommended that the minimum trench
width for the gravelless system be eighteen (18) inches in friable
soils to ensure proper backfill around the bottom half of the pipe.
In cohesive soils, the minimum width of excavation shall be twenty-four
(24) inches. In clay soils, it is recommended that the trench be backfilled
with sandy material, sandy loam, loam, clay loam, silt loam or silty
clay loam. The gravelless system may be installed at a trench bottom
depth of eighteen (18) inches minimum to thirty (30) inches maximum,
but a more shallow trench bottom depth of eighteen (18) to twenty-four
(24) inches is recommended. To promote equal effluent and suspended
solids distribution, the slope of the drain-pipe shall be from zero
(0) to one-half (½) inches per one hundred (100) feet.
b.
A gravelless chamber. May be installed based on
bottom absorption area utilizing a reduction of up to forty percent
(40%) for a fifteen (15) inch chamber and twenty-five percent (25%)
for a twenty-two (22) inch and thirty-four (34) inch chamber based
upon a soil morphology evaluation. However, as described in Table
613(a), the maximum loading rate provided for any particular soil
group must not be exceeded. For this purpose, the fifteen (15) inch
chamber may be considered equal to twenty-one (21) inches in width
of a standard absorption trench. The twenty-two (22) inch chamber
may be considered equal to twenty-eight (28) inches in width of a
standard absorption trench. The thirty-four (34) inch chamber may
be considered equal to forty-two (42) inches in width of a standard
absorption trench. Installation of the chamber system shall be in
accordance with this code except:
(1)
The installation shall be made in accordance with the manufacturer's
specifications;
(2)
The side walls of trenches placed in Group IV(a) soils shall
be raked to open pores which were damaged or sealed during excavation;
and
(3)
Chambers utilizing maximum sidewall absorption features shall
be installed per the manufacturer's recommendations to maximize the
use of upper soil horizons.
|
Table 613.15(b)
Loading Rate for Chamber Systems
| ||
|---|---|---|
|
Soil Group
|
Range for Chambers
(gpd/sq.ft.)
| |
|
I
|
1.0 — 1.2
| |
|
II
|
0.7 — 0.8
| |
|
III
|
0.5 — 0.6
| |
|
IV (a)
|
0.3 — 0.4
| |
|
IV (b)
|
Unsuitable
| |
|
V
|
0.4 — 0.6
| |
|
Note:
|
1.
|
Application rate is the effective area per lineal feet of the
chamber based on the actual dimensional width of the chamber at the
trench or bed bottom.
| |
|---|---|---|---|
|
2.
|
The loading rate shall be based on the most hydraulically limiting
naturally occurring soil horizon within three (3) feet of the ground
surface or to a depth of two (2) foot below trench bottom, whichever
is greater.
|
c.
A gravelless expanded polystyrene (EPS) aggregate system may be installed
in lieu of gravel systems at the sizing as shown below. For purpose
of calculation, the twelve (12) inch minimum diameter EPS aggregate
cylinder, with four (4) inch perforated distribution pipe, may be
considered equal to twenty-four (24) inches in width of a standard
absorption trench or at two (2) square feet. The twelve (12) inch
EPS aggregate shall be installed in an eighteen (18) to twenty-four
(24) inch wide trench. Installation of the gravelless EPS aggregate
system shall be in accordance with this code except:
16.
Dosing/alternating systems are encouraged, especially in slowly permeable
soil conditions.
17.
The Code Official may permit the use of a bed system on sites where
the minimum soil permeability is a loading rate of forty-five hundredths
(0.45) or faster and essentially meeting the other requirements of
this Section, and only on lots which are limited by topography, space
or other site planning considerations. In such cases the number of
square feet of bottom area needed shall be increased by fifty percent
(50%) over what would be required for a trench system. Distribution
lines shall be at least eighteen (18) inches from the side of the
bed and shall have lines on three (3) foot centers and care must be
taken to divert surface water away from the bed. When the design volume
of sewage exceeds six hundred (600) gallons per day, adequate space
shall be provided to accommodate a trench system for the absorption
field. There shall be no less than a two (2) foot separation between
the bed bottom and the limiting layer or seasonal high water table.
a.
Possible modifications to standard absorption systems, which may
be utilized to overcome selected soil and site limitations and must
be approved by the Code Official, and include the following:
(1)
Shallow placement of absorption trenches shall be utilized where
insufficient depth to seasonally high or perched water table or where
insufficient soil thickness prevents the placement of conventional
distribution lines in accordance with this Section. Shallow trenches
shall be designed and constructed to provide a minimum of two (2)
feet of natural soil separation between the trench bottom and the
uppermost elevation of the seasonally high or perched water table
and rock. Shallow trenches may be constructed by placing the top of
the gravel at original ground level and covering the absorption field
with loamy soil (sandy loam, loam, clay loam, silt loam or silty clay
loam) to a depth of eight (8) to twelve (12) inches at the center.
The cover over the absorption field shall extend at least five (5)
feet beyond the edge of any trench and have a turf grass cover established
immediately after construction. If an area is to be filled and the
trenches constructed in the fill with the bottom of the trenches in
at least six (6) inches of natural soil, the following procedures
must be followed:
(a)
The fill material shall be of a sandy texture with maximum clay
content of twenty percent (20%). The fill material shall not be hauled
or worked wet. The area to be filled must be protected from traffic
and small brush and trees removed prior to placement;
(b)
The soil surface must be loosened with a cultivator or garden
plow. This work must be done when the soil is dry;
(c)
The fill is moved onto the site without driving on the loosened
soil. The fill material is then tilled into the natural soil to create
a gradual transition between the two. The remaining fill is then added
in layers until the desired height is obtained with each layer being
tilled into the preceding layer; and
(d)
The site is then shaped to shed water and fill all low spots
before the absorption system is installed. After installation of the
absorption system, the site must have a turf grass cover established
as soon as possible;
(2)
Alternating dual field absorption systems may be utilized where
soils are limited by high clogging potentials, with loading rates
of two-tenths (0.2) gpd/square feet or in high shrink/swell potential
soils. Alternating dual field absorption systems shall be designed
with two (2) complete absorption fields, each sized a minimum of seventy-five
percent (75%) of the total area required for a single field and separated
by an effluent flow diversion valve. The diversion valve shall be
constructed to resist five hundred (500) pounds crushing strength,
structurally sound and shall be resistant to corrosion. A valve placed
below ground level shall be constructed so that it may be operated
from the ground surface; and
(3)
Sand-lined trenches may be used in areas where the soil has
greater than fifty percent (50%) rock fragments and there are severe
geological limitations. For a maximum loading rate of four-tenths
(0.4) gallons per day per square foot or a minimum of three hundred
(300) square feet per bedroom, the sand is not required to meet the
requirements for intermittent sand filters. The material shall be
natural or manufactured sand and have no more than fifteen percent
(15%) clay content. Manufactured sand shall be chat, fines manufactured
from igneous rocks or chert gravel or manufactured from crushed glass.
Crushed limestone is not acceptable. For higher loading rates, the
sand must meet the requirements for an intermittent sand filter.
(a)
In standard four (4) inch pipe and gravel trenches, the depth
of liner material must be twelve (12) inches below the gravel and
at least six (6) inches on the sides of the gravel up to the top of
the gravel. To place sand on the sides of the trenches, the trench
walls must be excavated on a slope instead of vertically. The side
slopes shall be two (2) horizontal to one (1) vertical and in no case
steeper than one (1) horizontal to one (1) vertical.
(b)
In gravelless pipe systems, the minimum thickness of liner material
is six (6) inches around the pipe.
(c)
The effluent to sand-lined systems in areas of potential ground
water contamination shall be equally distributed as much as practically
possible. Serial and drop box systems shall not be used. As a minimum,
a distribution box shall be used to evenly distribute the effluent
to the trenches.
(d)
The sand-lined trenches may be used, with the approval of the
Code Official, where the percentage of rock fragments is less than
seventy percent (70%) for at least four (4) feet below the trench
bottom. For sand-lined trenches to function properly, the permeability
of the natural material shall be similar to the permeability of the
liner material and lined trenches must not be used over fragipans
or other restrictive layers which have potential to perch water tables
and could cause saturation of the liner material.
[Ord. No. 11-0248 §1, 8-9-2011]
A.
General. The intent of this Section is to provide minimum
standards for the design, location, installation, use and maintenance
of alternative sewage treatment systems in areas of limiting soil
characteristics, where a standard system cannot be installed or a
standard system is not the most suitable treatment. These systems
shall be designed and stamped by a registered licensed designer. All
absorption systems shall have curtain drains, terraces or use of other
flow diversion methods to minimize surface or ground water from loading
the absorption field. Alternate systems shall have a Class 1 NSF International
aeration treatment unit.
B.
Low Pressure Pipe (LPP) System. A low pressure, two (2)
to four (4) foot pressure head, pipe system may be utilized where
soil and site conditions prohibit the installation of a conventional
or modified septic tank system due to the presence of shallow soil
conditions, seasonally high water table conditions and slow soil permeability.
The Code Official may permit the use of a LPP system where there are
cherty clay soils, severe geological limitations or both. The separation
distance in cherty clay soils, severe geological limitations or both
for ground water between the trench bottoms and bedrock shall be at
least two (2) feet. The amount of rock fragments shall be less than
fifty percent (50%) and in no case more than seventy percent (70%),
unless the trenches are lined with sand. If the soils have severely
diminished, soil qualities shall be sand lined.
1.
The LPP shall consist of the following basic components:
a.
A network of one (1) to two (2) inch diameter perforated PVC, one
hundred sixty (160) pounds per square inch pipe or equivalent placed
in natural soil no more than eighteen (18) inches in depth, and not
less than twenty-four (24) inches in width and spaced not less than
five (5) feet on center. Trenches shall include at least five (5)
inches of pea gravel below the pipe and two (2) inches above the pipe;
and four (4) inches of soil cover. The holes in the perforated pipe
shall be spaced from two (2) feet to no more than eight (8) feet.
The minimum hole size is five thirty-two seconds (5/32) inch;
b.
An approved Class 1 aeration unit or other approved pretreatment
system and a pumping or dosing tank. The pumping or dosing tank shall
be sized at a minimum of one thousand (1,000) gallons or one (1) day’s
storage above the pump, whichever is greater;
[Ord. No. 18-0499, 12-10-2018]
c.
A submersible sewage effluent pump (not a sump pump) with appropriate
on/off controls for controlled dosing and a high water alarm or other
approved pressure dosing and distribution system; and
d.
A water-tight supply manifold pipe for conveying effluent from the
pump to the low pressure network.
2.
The soil and site criteria for low-pressure pipe systems shall meet
the following minimum requirements:
a.
LPP absorption fields may be installed on slopes greater than ten
percent (10%), with special design procedures to assure proper distribution
of effluent over the absorption field.
b.
There shall be at least twenty-four (24) inches of separation between
the naturally occurring soil surface and bedrock, water-impeding formation,
seasonally high water table or evidence of chroma 2 mottles. This
twenty-four (24) inch depth shall consist of permeable soils with
loading rate in accordance with Table 614(a). The loading rate shall
be based on the most hydraulically limiting natural occurring soil
horizon within three (3) feet of the ground surface or to a depth
of one (1) foot below trench bottom, whichever is deeper. The bottom
of the proposed trenches must be located a minimum of two (2) feet
above rock, water-impeding formation, seasonally high water table
or where there is evidence of chroma 2 mottles. In areas where there
are severe geological limitations and the soils have a high chert
content, the bottom of the proposed trenches shall be at least four
(4) feet above bedrock unless an evaluation by a registered geologist
determines that the separation distance may be reduced.
3.
The following application rates shall be used in determining the
maximum application rate for low pipe systems:
a.
In calculating the number of square feet for the absorption field
(not square footage of trench bottom), the design sewage flow shall
be divided by the application rate from Table 614(a). The lateral
lines shall have a minimum spacing of five (5) feet on centers within
the areas calculated for the absorption field area; and of total area.
b.
The systems shall be designed so that the discharge from any one
(1) lateral line does not vary more than ten percent (10%) from the
other laterals. All laterals shall have an envelope of trench rock
surrounding the pipe. The trench rock shall be placed to a minimum
depth of four (4) inches below the pipe and two (2) inches above the
pipe.
4.
Design of the LPP shall comply with accepted practices and be specifically
approved by the Code Official. The system shall be designed and bear
the seal of a registered licensed designer.
|
Table 614(a)
Application Rates by Soil Group for Low Pressure Pipe
(LPP) Systems
| ||||
|---|---|---|---|---|
|
Soil Group
|
Soil Texture Classes
(USDA Classification)
|
Application Rate
*(gpd./sq. ft.)
| ||
|
Type
|
Texture
|
Classes
| ||
|
I**
|
Sands (with S or PS structure and clay mineralogy)
|
Sand, Loamy sand
|
No structure (Brown colors)
|
0.4
|
|
II
|
Coarse Loams (with S or PS structure and clay mineralogy)
|
Sandy loam, Loam
|
Granular; fine and medium subangular blocky
|
0.35
|
|
Sandy loam, Loam
|
Prismatic; coarse subangular and angular blocky
|
0.2
| ||
|
III
|
Fine Loams (with S or PS structure and clay mineralogy)
|
Silt loam, Clay loam, Sandy clay loam, Silty clay loam
|
Granular; fine and medium subangular blocky
|
0.2
|
|
Silt loam, Clay loam, Sandy clay loam, Silty clay loam
|
Prismatic; coarse subangular and angular blocky
|
0.15
| ||
|
IV(a)
|
Clays (with S or PS structure and clay mineralogy)
|
Sandy clay, Silty clay, Clay (low to moderate shrink/swell)
|
Granular; fine and medium subangular blocky
|
0.1
|
|
Sandy clay, Clay, Silty clay
|
Prismatic; coarse subangular or angular blocky
|
0.05
| ||
|
IV(b)
|
Sandy clay, Clay, Silty clay loam, Clay loam, Silty clay (high
shrink/swell potential)
|
Subangular, Angular blocky, or Prismatic
|
Not suitable
| |
|
V
|
Skeletal (less than 50% coarse fragments), Silt loam, Silty
clay loam, Clay, Silty clay
|
Anything but platy or massive
|
0.15
| |
|
*
|
Gallons of sewage tank effluent per day per square foot of total
area.
|
|---|---|
|
**
|
In areas where there are severe geological limitations and the
soils consist of greater than thirty-five percent (35%) gravel by
volume, the loading rate of two-tenths (0.2) gallons per day per square
foot (0.2 gpd/sq.ft.) shall be used.
|
|
The design loading rate of the LPP Systems shall be based on
the most hydraulically limiting naturally occurring soil horizon within
three (3) feet of the ground surface or to a depth of two (2) foot
below trench bottom, whichever is greater.
[Ord. No. 13-0459 §2, 12-10-2013] |
|
Table 614(b)
Application Rates by Soil Group for Drip Systems
[Ord. No. 13-0459 §2, 12-10-2013]
| ||||
|---|---|---|---|---|
|
Soil Group
|
Soil Texture Classes
(USDA Classification)
|
Application Rate
*(gpd./sq. ft.)
| ||
|
Type
|
Texture
|
Classes
| ||
|
I**
|
Sands (with S or PS structure and clay mineralogy)
|
Sand, Loamy sand
|
No structure (Brown colors)
|
0.5 — 0.4
|
|
II
|
Coarse Loams (with S or PS structure and clay mineralogy)
|
Sandy loam, Loam
|
Granular; fine and medium subangular blocky
|
0.4 — 0.35
|
|
Sandy loam, Loam
|
Prismatic; coarse subangular and angular blocky
|
0.3 — 0.2
| ||
|
III
|
Fine Loams (with S or PS structure and clay mineralogy)
|
Silt loam, Clay loam, Sandy clay loam, Silty clay loam
|
Granular; fine and medium subangular blocky
|
0.3 — 0.2
|
|
Silt loam, Clay loam, Sandy clay loam, Silty clay loam
|
Prismatic; coarse subangular and angular blocky
|
0.20 — 0.15
| ||
|
IV(a)
|
Clays (with S or PS structure and clay mineralogy)
|
Sandy clay, Silty clay, Clay (low to moderate shrink/swell)
|
Granular; fine and medium subangular blocky
|
0.2 — 0.1
|
|
Sandy clay, Clay, Silty clay
|
Prismatic; coarse subangular or angular blocky
|
0.1 — 0.05
| ||
|
IV(b) 1
|
Silty clay loam, Sandy clay: 35% to 40% clay (high shrink/swell
potential)
|
Fine, medium, and coarse subangular or angular blocky. Weak,
medium or strong grade. Prismatic structure: 0.05
|
0.1-0.075
| |
|
IV(b) 2
|
Sandy clay, Silty clay, Clay: 40% to 60% clay (high shrink/swell
potential)
|
Fine, medium, and coarse angular or subangular blocky. Weak,
medium or strong grade. Prismatic structure: 0.05
|
0.075-0.05
| |
|
IV(b) 3
|
Clay: greater than 60% (high shrink/swell potential)
|
Any size, grade or type of structure.
|
0.05
| |
|
V
|
Skeletal (less than 50% coarse fragments), loam, silty clay
loam, clay, silty clay
|
Anything but platy or massive
|
0.3 — 0.15
| |
|
*
|
Gallons of sewage tank effluent per day per square foot of total
area.
|
|
**
|
In areas where there are severe geological limitations and the
soils consist of greater than thirty-five percent (35%) gravel by
volume, the loading rate of two-tenths (0.2) gallons per day per square
foot (0.2 gpd/sq. ft.) shall be used.
|
|
***
|
Drip soil absorption system loading rate for soil classified
as being in Group IV(b), the maximum application rate shall be 0.10
gpd/sq. ft.
|
|
The design loading rate for drip systems shall be based on the
most hydraulically limiting naturally occurring soil horizon within
twenty (20) inches of the ground surface or to a depth of one (1)
foot below trench bottom, whichever is greater. Class IV(b) soils
shall not be considered a hydraulically limiting naturally occurring
soil horizon.
|
C.
Wastewater Stabilization Pond (Lagoon). A lagoon can provide
satisfactory sewage treatment in rural areas where soils are not suited
for absorption systems. No more than one (1) single-family residence
will be allowed on one (1) lagoon.
1.
The following minimum separation distances are outlined in Table
602.1.
2.
Lagoons may be utilized when there are no significant limitations
related to ground water from their use and the soils have been demonstrated
to be very slowly permeable such as percolation rates slower than
one hundred twenty (120) minutes per inch. There shall be either a
minimum separation distance between the lagoon bottom and creviced
bedrock of three (3) feet or installation of a clay liner with a minimum
thickness of one (1) foot or a synthetic liner, either of which must
be acceptable to the Code Official. Percolation losses from the lagoon
shall not exceed one-eighth (⅛) inch per day to prevent ground
water contamination or nuisance conditions. Site modifications may
be accomplished to provide these soil requirements. In areas of severe
geological limitations, restrictive layers such as fragipans shall
be a minimum of twelve (12) inches thick and shall not be breached
during construction.
3.
Slopes greater than fifteen percent (15%) shall be avoided.
4.
Timber shall be removed for a distance of fifty (50) feet from the
water's edge to enhance wind action and prevent shading.
5.
The Code Official shall require that a minimum one thousand (1,000)
gallon septic tank or ATU precede the lagoon. If irrigation of the
effluent is required to maintain the wastewater on the property from
which it originated, a septic tank or ATU shall precede the lagoon.
The use of a septic tank or ATU shall not be used as a basis for reduction
of the setback distances as set forth in Table 602.1.
6.
The lagoon shall be designed on the basis of five hundred (500) square
feet of water surface area per bedroom at the three (3) foot operating
level. The minimum water surface area at the three (3) foot level
shall be nine hundred (900) square feet.
7.
A single cell is generally acceptable for single residence lagoon
systems. If multiple cells are used for further polishing or storing
of the effluent, the secondary cell shall be at least one-half (½)
the size of the primary cell.
8.
The minimum embankment top width shall be least four (4) foot. The
embankment slopes shall not be steeper than three to one (3:1) on
the inner and outer slopes. Inner embankment slopes shall not be flatter
than four to one (4:1). Outer embankment slopes shall be sufficient
to prevent the entrance of surface water into the lagoon. Freeboard
shall be at least twenty-four (24) inches.
9.
To minimize erosion and facilitate weed control, embankment shall
be seeded with a locally hardy grass from the outside toe to one (1)
foot above the water line. Alfalfa or similar long-rooted crops, which
might interfere with the structure of the embankment, shall not be
used.
10.
The influent line shall be of a sound, durable material of water-tight
construction of SDR 35 or greater. The line shall have a minimum diameter
of four (4) inches and be laid on a firm foundation at a minimum grade
of one-eighth (⅛) inch per foot from the point of entry into
the lagoon. A cleanout or manhole shall be provided in the influent
line near the lagoon embankment. From this point the line shall either
be laid to the inner toe of the embankment and then on the bottom
of the lagoon to the terminus point or the line shall be supported
and secured every five (5) feet. A concrete splash pad three (3) feet
square shall be placed under the terminus of the pipe.
The elevation of the cleanout or manhole bottom shall be a minimum
of six (6) inches above the high water level in the lagoon.
11.
The lagoon shall be shaped so there are no narrow or elongated portions.
Rectangular cells shall have a length not exceeding three (3) times
the width. No islands, peninsulas or coves shall be permitted. Embankments
shall be rounded at corners to minimize accumulation of floating materials.
12.
The floor of the lagoon shall be stripped of vegetation and leveled
to the proper elevation. Organic material removed from the lagoon
area shall not be used in embankment construction. The lagoon shall
be sealed to prevent excessive exfiltration. Seals consisting of soils
must be adequately compacted by the construction equipment.
13.
Embankments shall be constructed of impervious materials and compacted
sufficiently to form a stable structure with very little settlement.
14.
The lagoon area shall be enclosed with a fence conforming to the
following conditions:
a.
The fence is at least five (5) feet in height;
b.
Fence post shall be galvanized and/or painted steel. The fence shall
be chain link or welded type material with no smaller than fourteen
(14) gauge wire. The holes in the wire shall not be larger than two
(2) horizontal by four (4) vertical. Metal post and metal top rail
shall be used;
c.
Fence posts shall be driven, tamped or set in concrete. Line posts
shall be at least eighteen (18) inches deep and shall be spaced no
more than ten (10) feet apart. Corner posts shall be at least twenty-four
(24) inches deep and shall be properly braced;
d.
The fence shall be of sound construction with no gaps or openings
along the bottom;
e.
The fence shall be no closer than the center of the berm to the waters
edge at the three (3) feet deep operating level. Fence setbacks shall
not exceed thirty (30) feet from the water's edge;
f.
A properly hinged four (4) foot high gate or comparable materials
to be installed and provided with an effective latching device. The
gate shall be minimum forty-eight (48) inches in width to accommodate
maintenance and mowing equipment; and
g.
The fence shall be completed prior to occupancy of the dwelling.
h.
The lagoon must be posted "KEEP OUT" on four (4) sides each opposite
of another.
15.
There shall be no permanent connection of any roof drain, footing
drain or any source of rainwater to the lagoon.
16.
Odor problems caused by spring turnover of water, temporary overloading,
ice cover, atmospheric conditions or anaerobic conditions may be controlled
by broadcasting sodium or ammonium nitrate over the surface of the
pond. In general, the amount of sodium or ammonium nitrate shall not
exceed two (2) pounds per day until the odor dissipates.
17.
Lagoons shall be designed with a four-inch diameter outfall pipe
drawing effluent from eight (8) inches below the operating surface.
All outfall discharge shall be kept on the subject property.
[Ord. No. 18-0499, 12-10-2018]
D.
Elevated Sand Mounds. Elevated sand mounds may be considered
whenever site conditions preclude the use of absorption trenches.
The construction of a mound shall be initiated only after a site evaluation
has been made and landscaping, dwelling placement, effect on surface
drainage and general topography has been considered.
1.
Elevated sand mounds shall not be utilized on soils where the high
ground water level as evidenced by mottling, bedrock or other strata
having a percolation rate slower than one hundred twenty (120) minutes
per inch occurs within twenty-four (24) inches of natural grade. In
areas where there is a significant potential for ground water contamination,
a registered licensed designer shall determine the amount of soil
needed. Mounds shall be constructed only upon undisturbed naturally
occurring soils.
2.
Elevated sand mounds are subject to the setback distances required
in Table 602.1.
3.
The fill material from the natural soil plowed surface to the top
of the rock-filled bed shall be sand, loamy sand or sandy loam. Loading
rates on the sand fill shall not exceed the values in Table 614.5(a).
|
Table 614.5(a)
Loading Rates for Soil Textures
Suited to Use as Fill in a Mound System
| ||
|---|---|---|
|
Texture
|
Loading Rate
(gal./sq. ft./day)
| |
|
Medium to coarse sand
|
1.2
| |
|
Fine sand
|
1.0
| |
|
Loamy sand
|
0.8
| |
|
Sandy loam
|
0.6
| |
|
Note: Rock fragments larger than one-sixteenth
(1/16) inch shall not exceed fifteen percent (15%) by volume of the
material used for sandy fill.
| ||
4.
There shall be a minimum of two (2) feet of fill material and six (6) inches of naturally occurring soils between the bottom of the trench rock and the highest elevation of the limiting conditions as defined in Subsection (D)(1). If the area to be filled has less than six (6) inches of existing soil between bedrock and the fill material, a minimum of six (6) inches of Group I soil shall be filled above the bedrock before placing Group II soil. The area to be filled shall extend twenty (20) feet minimum beyond the edge of the drainfield trenches in all directions.
5.
Whenever possible, mounds shall be located on flat areas or crests
of slopes. Mounds shall not be located on natural slopes of more than
six percent (6%) if the percolation rate is slower than sixty (60)
minutes per inch to a depth of at least twenty-four (24) inches below
the sand layer. Mounds may be located on slopes up to a maximum of
twelve percent (12%) if the soil percolation rate is faster than sixty
(60) minutes per inch to a depth of twenty-four (24) inches below
the sand layer.
6.
The width of the trench rock in a single bed shall not exceed ten
(10) feet.
7.
The required bottom area of the trenches or bed and the effective
basal area of the mound shall be based on one hundred twenty (120)
gallons per bedroom per day. The basal area of the mound shall have
the minimum area as shown in Table 614.5(b).
[Ord. No. 13-0459 §2, 12-10-2013]
|
Table 614.5(b)
Loading Rate for Mound Systems
| ||
|---|---|---|
|
Percolation Rate
(min./in.)
|
of Basal Area
(gpd/sq. ft.)
| |
|
1 — 30
|
1.2
| |
|
31 — 45
|
0.75
| |
|
46 — 60
|
0.5
| |
|
61 — 120
|
0.25
| |
8.
The area of sand fill shall extend beyond the basal area and the
sides shaped to a three to one (3:1) or four to one (4:1) slope. The
sand fill shall be covered with six (6) inches of fine textured soil
and a final cap of six (6) inches of good topsoil applied. Also the
mound shall be seeded with a grass to establish a turf grass cover
as soon as possible. No shrubs shall be planted on the top of the
mound.
9.
The land area fifty (50) feet down slope of the elevated sand mound
is the effluent dispersal area and the soil in this area shall not
be removed or disturbed.
10.
Dosing shall be required for all elevated sand mounds. The mound
shall be dosed not more than two (2) times per day. The size of the
dosing pump shall be selected to maintain a minimum pressure of one
(1) pound per square inch (1 psi), two and three-tenths (2.3) feet
of head, at the end of each distribution line.
a.
Perforation holes and hole spacing shall be determined to insure
equal distribution of the effluent throughout the bed or trenches.
b.
The perforated pipe laterals shall be connected to a two (2) inch
diameter manifold pipe with the ends capped. The laterals shall be
spaced no farther than forty (40) inches on center and no farther
than twenty (20) inches from the edge of the trench rock. The perforated
pipe laterals shall be installed level, with the perforations facing
downward. There shall be a minimum of nine (9) inches of trench rock
below the laterals and two (2) inches above the laterals. The material
used to cover the trench rock shall be untreated building paper, six
(6) inches of compacted straw or three and one-half (3.5) inch unbacked
fiberglass insulation or a geotextile.
c.
The manifold pipe shall be connected to the supply pipe from the
pump. The manifold shall be sloped toward the supply pipe from the
pump. Backflow valves are prohibited in the pump discharge line. The
pump discharge line shall be graded to permit gravity flow to the
absorption area or back to the dosing tank. Proper air relief and
anti-siphon devices shall be installed in the piping to prevent siphoning
of effluent from the dosing tank or from the mound.
11.
Prior to preparing the area selected for the mound, above ground
vegetation must be closely cut and removed from the ground surface.
Prior to plowing, the dosing pump discharge line shall be installed
from the pump chamber to the point of connection with the distribution
manifold. The area shall then be plowed to a depth of seven (7) to
eight (8) inches parallel to the land contour with the plow throwing
the soil upslope to provide a proper interface between the fill and
natural soils. In no case shall a rubber-tired tractor be used after
the surface preparation is completed. Tree stumps shall be cut flush
with the surface and the roots shall not be pulled. The soil shall
be plowed only when the moisture content of a fragment eight (8) inches
below the surface is below the plastic limit.
12.
Mound construction shall proceed immediately after surface preparation
is completed.
a.
A minimum of twelve (12) inches of sand fill shall be placed where
the trench rock is to be located. A crawler tractor with a blade shall
be used to move the sand into place. At least six (6) inches of sand
shall be kept beneath equipment to minimize compaction of the plowed
layer. The sand layer upon which the trench rock is to be placed shall
be level.
b.
After hand leveling of the trench rock, the distribution system shall
be placed and the pipes covered with two (2) inches of rock. After
installation of the distribution system, the entire mound is to be
covered with topsoil native to the area. The entire mound shall be
crowned by providing twelve (12) inches of topsoil on the side slopes
with a minimum of eighteen (18) inches over the center of the mound.
The entire mound shall then have a turf grass cover established to
assure stability of the installation.
c.
The area surrounding the elevated sand mound shall be graded to provide
diversion of surface runoff waters.
E.
Holding Tank Sewage System.
1.
A holding tank is an alternative to an on-site sewage treatment system
with very special system and limited applications, such as:
a.
Controlled commercial usage with design flows of less than fifty
(50) gallons per day on situations, such as vehicle parks, dump stations,
campgrounds, marinas, etc.
b.
Repair of failing on-site sewage systems.
c.
Emergency situations where an approved repair or replacement system
installation is delayed due to weather induced soil or site conditions.
d.
Where Missouri DNR has issued a sewer construction permit for a system
using a temporary holding facility pending completion of an approved
central wastewater and collection treatment system.
3.
Operation and maintenance.
a.
The Code Official shall require an operating permit renewal every
two (2) years.
b.
Pumping, hauling and disposal must be by a sewage-pumping contractor.
c.
Disposal of sewage from a holding tank system must be at a site approved
by the Missouri Department of Natural Resources.
d.
Operation records must be maintained by the owner and pumper which
include information about pumping frequency, sewage volume, disposal
site, proof of acceptance by the disposal site operator, alarms, and
system serving and repairs.
e.
Copies of operation records must be maintained according to the permit
requirements and made available to the Code Official upon request.
f.
Pumping service contracts. Before a permit is issued
for installation of a holding tank sewage system, the owner of the
system must submit to the Code Official complete documentation in
a manner prescribed by the Code Official, and address these items
to the satisfaction of the Code Official:
(1)
Service contract with a sewage system-pumping contractor.
(2)
Frequency of pumping, by schedule or call-for-service.
(3)
Financial guarantee for operation, such as a cash
deposit or an assignment of funds, in the amount specified by the
Code Official. The financial guarantee shall be in an amount at least
equal to the cost of three (3) months' service.
[Ord. No. 13-0459 §2, 12-10-2013]
4.
A holding tank shall be constructed of the same materials and by
the same procedures as those specified for water-tight sewage tanks.
A manhole of at least twenty (20) inches in diameter shall extend
from inside the tank to a point that is at least six (6) inches above
finish grade. The manhole lid shall be locked down and water-tight.
5.
The tank shall be protected against flotation under high water table
conditions. This shall be achieved by weight of the tank, earth anchors
or shallow bury depths.
6.
Capacity.
[Ord. No. 13-0459 §2, 12-10-2013]
a.
For a residence, the tank size shall be one thousand (1,000) gallons
or six hundred (600) gallons times the number of bedrooms, whichever
is greater.
b.
For permanent structures, other than residences, the capacity shall
be based on measured flow rates or estimated flow rates. The tank
capacity shall be at least seven (7) times the daily flow rate. Reserve
storage volume three (3) times the daily flow rate.
8.
Holding tanks shall be monitored to minimize the chance of accidental
sewage overflows. Techniques such as visual observation, warning lights
or bells, or regularly scheduled pumping shall be used. For commercial
establishments, a positive warning system shall be installed, which
allows twenty-five percent (25%) reserve capacity after actuation.
F.
Sand Filters. ATUs and sand filters may be used along with
soil absorption systems in soils with a loading rate of two-tenths
(0.20) gpd/sq.ft. Soil absorption systems may be reduced by up to
one-third (⅓) of that required for a conventional soil absorption
system.
1.
The ATU must be in accordance with Section 705.360 of this code. Setback distances as shown in Table 602.1 shall apply except that the minimum distance to the down-slope property line shall be fifty (50) feet.
2.
The following shall apply to gravity flow sand filter systems:
a.
All piping in a sand filter shall be four (4) inch polyvinyl chloride
(PVC). Perforated pipe shall be used for distribution and collection
lines;
b.
All sand filters shall be dosed so as to provide uniform distribution
of wastewater throughout the filter cross-section and allow time for
re-aeration of the pore spaces to occur. Dosing shall be accomplished
by either pumps or siphons;
c.
Effluent from filter under-drains shall be collected and disposed
of properly and effluent shall not discharge;
d.
Buried sand filters shall be in conformance with Table 614.7. One
(1) collector line shall be provided for every six (6) feet of bed
width, with a minimum of two (2) collector lines per bed. The collector
lines shall have a minimum grade of one percent (1%); and
(1)
Distribution lines shall be level and spaced a maximum of three
(3) feet apart. Each distribution line shall be vented (downstream
end) or connected to a common vent. Vents shall extend at least twelve
(12) inches above the ground surface with the outlet screened or capped
(perforated).
(2)
ATU effluent shall be applied to the filter through a distribution
box. Buried filters shall be dosed with a pump or siphon. The dosing
volume shall be sufficient to fill the pore spaces in the gravel to
a depth of four (4) inches. For single bed filters receiving septic
tank effluent, the hydraulic loading rate shall not exceed one (1)
gallon per day per square foot with a maximum organic loading of one
and three-fourths (1.75) pounds of biological oxygen demand (BOD)
per day per one thousand (1,000) square feet of surface area. Total
surface area shall not be less than two hundred (200) square feet.
e.
Open sand filters are similar to buried filters with the exception
that no soil backfill is used on the top of the sand filter. Open
sand filters shall be in conformance with Table 614.7.
(1)
Distribution of wastewater shall be applied by pipes directly
over the sand surface at the center of the bed or at the four (4)
corners. Splash plates beneath points of discharge shall be used to
prevent erosion of the sand. Curbs around the splash plates or large
stones placed around the periphery of the plate will help prevent
scouring. All exposed pipes shall slope to drain.
(2)
Filter walls shall be concrete, masonry, compacted clay, high
density polyethylene plastic with a minimum thickness of thirty (30)
mil, or other material acceptable to the Code Commission; and extend
six (6) inches above the sand and six (6) inches above the adjacent
ground level.
(3)
Dosing shall flood the bed to a depth of two (2) inches with
a hydraulic loading of two (2) to five (5) gallons per day per square
foot (septic tank effluent). Maximum organic loading is five and thirteen-hundredths
(5.13) pounds of BOD per day per one thousand (1,000) square feet
of surface area.
(4)
The filter shall be covered to provide protection against severe
weather, prevent growth of weeds and to keep children and animals
out of the filter. Such cover may include six (6) inches of clean
one (1) to two (2) inch gravel, if so designed by an engineer as part
of the system. In such event, a vent for the system would not be required
if so determined by the registered licensed designer.
|
Table 614.7
Design Guidelines for Intermittent Sand Filters
| |||
|---|---|---|---|
|
Parameter
|
Buried Filters
|
Open Filters
| |
|
Pretreatment
|
Class 1
|
Class 1
| |
|
Setback Distance
| |||
|
Residences
|
50 ft.
|
200 ft.
| |
|
Water Supplies
|
100 ft.
|
100 ft.
| |
|
Backfill Depths
|
12-inch minimum
| ||
|
Distribution
| |||
|
Gravel
|
6" (¾" — 2½")
|
None
| |
|
Pipe
|
4" PVC Perforated
|
PVC or equivalent
| |
|
Venting
|
Downstream end
| ||
|
Dosing Frequency
|
>2 per day
|
>2 per day
| |
|
Hydraulic Loading
|
1.0 gpd/sq. ft.
|
2 — 5 gpd/sq. ft.
| |
|
Barrier Material
|
3½ fiberglass; untreated building paper (4,060 lb.);
synthetic fabric; 8" straw
|
None
| |
|
Sand
| |||
|
Effective size
|
0.3 — 1.22 mm
|
0.3-1.22 mm
| |
|
Uniformity coefficient
|
<3.5
|
<3.5
| |
|
Fines (<0.13 mm)
|
<1% (by wt.)
|
<1% (by wt.)
| |
|
Depth
|
24 — 36"
|
24 — 36"
| |
|
Collector Lines
| |||
|
Minimum Number
|
2/bed; 1 line per 6' width
|
2/bed; 1 line per 6" width
| |
|
Slope
|
1% minimum
|
1% minimum
| |
|
Gravel
|
4" overpipe (¾ — 2½")
|
4" overpipe (¾ — 2½")
| |
|
Pea Gravel
|
3" (⅛ — ⅜")
|
3" (⅛ — ⅜")
| |
|
Pipe
|
4" PVC Perforated
|
4" PVC Perforated
| |
3.
The following shall apply to pressure dosed sand filter systems:
a.
Conventional pressure dosed sand filters use an intermittent filter
with two (2) feet or more of medium sand designed to filter and biologically
treat sewage tank effluent from a pressure distribution system at
an application rate not to exceed one and twenty-five hundredths (1.25)
gallons per square foot sand surface area per day, applied at a dose
not to exceed one-half (½) gallon per orifice per dose. These
sand filters may be buried or open.
b.
Recirculating pressure dosed sand filters use a recirculating filter
with two (2) feet or more of medium filter media designed to filter
and biologically treat sewage tank effluent from a pressure distribution
system at an application rate not to exceed five (5) gallons per square
foot filter surface per day, applied at a dose not to exceed two (2)
gallons per orifice per dose. These sand filters shall be uncovered
and open to the surface.
c.
Minimum filter area for these filters shall be as follows:
(1)
Conventional pressure dosed sand filters for single-family residences
shall be a minimum of three hundred sixty (360) square feet in surface
area with a design sewage flow not to exceed six hundred (600) gallons.
If sand filter design flows exceed an average of four hundred fifty
(450) gallons per day, the minimum sand surface will be based on one
and twenty-five hundredths (1.25) gallons per day per square foot;
and
(2)
Pressure dosed sand filters for commercial facilities shall
be sized on the basis of projected daily sewage flow. If the waste
strength is proposed to be greater than residential strength waste,
pretreatment shall be required which will reduce the biological oxygen
demand to levels not to exceed three hundred (300) BOD, TSS to levels
not to exceed one hundred fifty (150), and oil and grease to levels
not to exceed twenty-five (25). The minimum sand surface will be based
on two (2) to five (5) gallons per day per square foot.
d.
Design criteria shall include the following:
(1)
Sewage tanks shall be in accordance with Section 705.260. Setback distances as shown in Table 602.1 shall apply. Tanks shall be water-tight and tested in the field. The test shall be performed by filling the tank two (2) inches above the riser inlet. At the end of the first twenty-four (24) hour period, the tank water level shall be refilled. After another twenty-four (24) hour period, no more than one (1) inch of water shall have dropped from the original reading. Risers shall have a water-proof epoxy seal between the tank and riser;
(2)
Pumping systems for a pressure dosed sand filter system shall
provide pumping apparatus that is capable of filtering gross solids
larger than one-eighth (⅛) inch and draw from the clear zone
near the outlet side of the sewage tank. This zone is described as
the layer of effluent between the sludge and scum layers of the sewage
tank. Pumps shall be able to deliver adequate head pressure to control
orifice plugging. Pumps shall be made of a corrosive-resistant material
such as Type 316 stainless steel, suitable plastic, or 85-5-5-5 bronze.
Screens shall have at least ten (10) square feet of surface area,
with one-eighth (⅛) inch openings;
(3)
Operation controls shall be on a timer dose that distributes
the average daily flow over an eighteen (18) hour period. Recirculating
filters will be set to recirculate five (5) times the average daily
flow over a twenty-four (24) hour period. Systems shall be designed
with a high water alarm and light signal. Control panels shall be
located on an exterior location. Control operations shall be located
in an area available for maintenance;
(4)
Intermittent filter media shall be a mixture of sand or durable
inert particles with one hundred percent (100%) passing the three-eighths
(⅜) inch sieve; ninety percent (90%) to one hundred percent
(100%) passing the Number 4 sieve; sixty-two percent (62%) to one
hundred percent (100%) passing the Number 10 sieve; forty-five percent
(45%) to eighty-two percent (82%) passing the Number 16 sieve; twenty-five
percent (25%) to fifty-five percent (55%) passing the Number 30 sieve;
ten percent (10%) or less passing the Number 60 sieve; four percent
(4%) or less passing the Number 100 sieve; or sand meeting the ASTM-C
33 concrete sand specification minus four percent (4%) or less passing
the Number 100 sieve. All drainage rock shall be river washed, hardened
and weathered rock. The treatment media will be two (2) inches deep
and of a coarse media with an effective size of one and one-half (1½)
to three (3) millimeters and a uniformity coefficient of less than
two (2). Limestone or dolomite is not acceptable for drainage rock;
(5)
Recirculating filter media shall be a mixture of sand or durable
inert particles with one hundred percent (100%) passing the three-eighths
(⅜) inch sieve; seventy-nine percent (79%) to one hundred percent
(100%) passing the Number 4 sieve; eight percent (8%) to ninety-two
percent (92%) passing the Number 8 sieve; zero percent (0%) to fifteen
percent (15%) passing the Number 30 sieve; zero percent (0%) to one
percent (1%) passing the Number 50 sieve. All drainage rock shall
be river washed, hardened and weathered rock. The treatment media
will be two (2) inches deep and of a coarse media with an effective
size of one and one-half (1.5) to three (3) millimeters and a uniformity
coefficient of less than two (2). Limestone or dolomite is not acceptable
for drainage rock; and
(6)
Container designs may be concrete containers consisting of water-tight
walls and floors to prevent ground water from infiltrating or effluent
from exfiltrating from the filter. All penetrations through the walls
shall be water-tight. Containers may also consist of a thirty (30)
mil polyvinyl chloride liner covering the sand filter bottom and side
wall areas. Polyvinyl chloride liners should be supplied with repair
kits and boots for passage through the liner wall. The bottom area
of the liner shall be bedded in two (2) inches of leveling sand. The
liner shall be constructed to form a water-proof membrane between
the trench bottom and trench walls. The polyvinyl liner shall incorporate
all seams to be a chemically or heat bonded water-proof seam.
e.
The filter design criteria shall include the following:
(1)
The interior base of the filter container shall be level or
constructed at a grade of one percent (1%) or less to the under-drain
pipe elevation;
(2)
The under-drain piping shall consist of a pipe with one-fourth
(¼) inch grooves cut every four (4) inches along the pipe length
to a depth of one-half (½) of the pipe diameter. The bottom
of the filter container shall be covered with a minimum of six (6)
inches of drain media. The under-drain pipe shall be enveloped in
an amount and depth of drainage rock to prevent migration of the under-drain
media into the pipe perforations;
(3)
A minimum of twenty-four (24) inches of approved filter media
shall be installed over the under-drain media. The media shall be
damp at the time of installation to insure compaction of the media.
The top surface of the media shall be level;
(4)
There shall be a minimum of three (3) inches of clean drain
media below the distribution laterals and sufficient media above the
laterals equal to or covering the orifice shields and/or pipe;
(5)
Distribution laterals shall be evenly spaced on minimum, thirty
(30) inches on centers. Orifices shall be placed such that there is
one (1) orifice or more on average per six (6) square feet of sand
surface. Orifice holes shall be one-eighth (⅛) inch in diameter.
The diameter of the piping manifold and lateral shall be no less than
one-half (½) inch. The ends of the distribution laterals shall
be constructed with a means to perform flushing of the piping, collectively
or individually, through the operation of a flushing valve;
(6)
The top of the intermittent media in which the pressure distribution
system is installed shall be covered with a breathable nylon or polypropylene
spun filter fabric rated at eighty-five hundredths (0.85) ounce per
square yard to eliminate soil intrusion into the filter media. Recirculating
filters shall be open-topped;
(7)
The top of the intermittent sand filter area shall be backfilled
with a soil cover, free of rocks, vegetation, wood waste, etc. The
soil cover shall have a textural class of loamy sand. The soil cover
shall have a minimum depth of six (6) inches and a maximum depth of
twelve (12) inches. Intermittent sand filters designs may delete soil
cover and incorporate three (3) to six (6) inches of a quality cypress
or cedar mulch over the entire filter area;
(8)
Where the effluent from a sand filter is to be discharged via
a pump, the pump and related apparatus shall be housed in a vandal-resistant
vault designed to withstand the stresses placed upon it and not allow
the migration of drain media, sand or under-drain media to its interior.
The vault shall have a durable, affixed floor. The vault shall provide
water-tight access to the finished grade with a diameter equal to
that of a gravity discharge sand filter. The depth of the under-drain
and the operational level of the pump cycle and alarm shall not allow
effluent to come within two (2) inches of the bottom of the sand filter
media. The pump off level shall be no lower than the invert of the
perforations of the under-drain piping. The internal sand filter pump
shall be electrically linked to the sand filter dosing apparatus in
such a manner as to prevent effluent from entering the sand filter
in event the internal sand filter pump fails; and
(9)
Other sand filters which vary in design from those described
in this code may be approved on experimental basis by the Code Commission,
if it can be demonstrated to produce a comparable effluent quality.
G.
Drip Soil Absorption. Drip soil absorption, also known as trickle irrigation, may be approved by the Code Official in accordance with Section 705.420. The installation shall be made in accordance with the manufacturer's specifications.
[Ord. No. 13-0459 §2, 12-10-2013]
1.
Drip lines shall be placed two (2) feet apart in a parallel
arrangement. Emitters shall be placed in the drip lines every two
(2) feet so there will be a two-foot-by-two-foot grid pattern. Other
configurations and spacing of the drip line and emitters may be used
in accordance with the manufacturer's recommendations.
2.
The application rate shall not exceed the values as shown in Table
614(b).
3.
Drip soil absorption systems may be allowed at sites where the
soil is classified as being in Group IV(b). A minimum separation distance
of twelve (12) inches shall be maintained between the drip lines and
emitters and a high ground water table or other limiting condition.
The maximum application rate for IV(b) soils shall be one-tenth (1/10)
gallons per day per square foot of absorption field.
H.
Wetlands. Constructed wetlands provide secondary levels
of treatment, which means that some form of pretreatment (ATU, lagoon,
etc.) must be used prior to the wetland, as wetlands cannot withstand
large influxes of suspended solids. The pretreatment used must be
capable of removing a large portion of these solids. Effluent from
wetlands must be contained on the owner's property with the same setback
distances as required for lagoons in Table 602.1.
1.
Free water surface wetlands are shallow beds or channels with a depth
less than twenty-four (24) inches and filled with emergent aquatic
plants. This type of wetland shall not be allowed.
2.
Submerged flow wetlands are similar to free water surface wetlands
except that the channels are filled with shallow depths of rock, gravel
or sand. The depth of the porous media is usually less than eighteen
(18) inches. The porous media supports the root systems of the emergent
aquatic vegetation. The water level is to be maintained below the
top of the porous media so that there is no open water surface.
3.
The surface area of wetlands shall be determined by using the following
equation:
|
As
|
=
|
[Q(lnCo - lnCe)) / kT x f x d)
| ||
|
Where:
|
As
|
=
|
wetland surface area, sq. ft.
| |
|
|
Q
|
=
|
daily bow rate to wetland, cu. ft./day
([gallons/day] + 7.5);
| |
|
|
Co
|
=
|
influent BOD5 concentration, mg/l;
| |
|
|
Ce
|
=
|
effluent BOD5 concentration, mg/l;
| |
|
|
kT
|
=
|
temperature dependent rate constant, per day;
| |
|
|
d
|
=
|
water depth in wetland, ft.; and
| |
|
|
f
|
=
|
void fraction of rock media, decimal.
|
4.
After a surface area has been determined, a cross sectional area
shall be calculated against hydraulic loading by using the following
equation:
|
Ah
|
=
|
Q/(Kh x S)
| ||
|
Where:
|
Ah
|
=
|
cross sectional area (hydraulic loading), sq. ft.;
| |
|
|
Kh
|
=
|
hydraulic conductivity of rock media, ft./day*; and
| |
|
|
S
|
=
|
slope of wetland bottom, decimal**
| |
|
|
*
|
A value of eight hundred (800) feet per day may be used for
the hydraulic conductivity for rock of one (1) inch diameter.
| ||
|
|
**
|
Values for slope shall range between one-quarter percent (0.25%)
to one percent (1%).
| ||
5.
After the hydraulic loading has been determined, an organic loading
shall be calculated using the following equation:
|
Ao
|
=
|
OGL/0.05
| ||
|
Where:
|
Ao
|
=
|
cross sectional area (organic loading), sq. ft.; and
| |
|
|
OGL
|
=
|
organic loading, lbs. BOD5/day
|
6.
The larger of the two (2) calculations, the hydraulic loading or
the organic loading, shall be used to determine the wetland dimensions.
7.
The width of the wetland shall be calculated by dividing the larger
cross-sectional area by the water depth. The calculated width shall
not be less than one-third (⅓) of the length (a length-width
ratio of three to one (3:1)). Should it be necessary to construct
a wetland with a ratio greater than three to one (3:1), step-loading
along the length of the wetland shall be considered.
8.
The configuration of a wetland for an individual home can be a one
(1) cell or two (2) cells in series, depending upon the soil properties
at the site. Larger systems may consist of multiple cells in parallel
or series in order to provide more management options.
a.
Single cells may be used where there will be no percolation of water
through the bottom of the wetland. Water movement properties of the
soil at the wetland construction site must be determined by use of
a properly performed soil profile analysis performed by a qualified
person meeting the criteria of 19 CSR 20.3.080.
b.
For soils with loading rates of two-tenths (0.2) gal./sq. ft. or
less and where geological limitations are not severe, a two (2) cell
wetland may be used. The first (1st) cell shall be lined, allowing
no percolation. The second (2nd) cell may be unlined and filled with
sand (not rock) to promote some percolation from the bottom of the
wetland. The second (2nd) cell shall not be larger than the first
(1st) cell.
9.
Crushed limestone or other rock with sharp edges shall not be used
for a porous media as this type of rock will compact with time. Rock
with rounded edges, such as creek gravel, shall be used. Rock must
be thoroughly washed to remove fines, which may cause plugging. Rock
substrate size shall be one (1) inch diameter, while rock to be used
around inlet and outlet pipes may be two (2) to four (4) inches in
diameter to reduce potential clogging. A three (3) to four (4) inch
layer of washed pea gravel may be used on top of the one (1) inch
substrate for decorative purposes.
10.
All piping shall be Standard Dimension Ration (SDR) 35 sewer pipe,
Schedule 40 polyvinyl chloride (PVC) drain, waste, and vent (DWV)
pipe, or material of equivalent or stronger construction. Piping shall
be a four (4) inch diameter.
11.
Influent shall be distributed and effluent collected by header pipes
running the width of the wetland. Perforated sewer pipe can be used
for the headers. For unperforated pipe, a one and one-half (1.5) inch
hole shall be drilled every twelve (12) inches along the header. Headers
shall be placed at the bottom of the wetland on a bed of rock and
covered with two (2) to four (4) inch rock. A cleanout shall be placed
before the influent header.
a.
If effluent from the septic tank flows to the wetland by gravity
and there are parallel cells in the wetland, a distribution box shall
be placed ahead of the wetland so that flow can be controlled to individual
cells.
b.
If effluent is pumped, the pumping rate shall not exceed twenty-five
(25) gallons per minute and no more than one-third (⅓) of the
daily design flow shall be pumped at one (1) time.
12.
Water level in a wetland shall be controllable. The range of control
shall be from two (2) inches above the surface of the rock to complete
draining of the wetland. Maximum water level in the wetland shall
be a minimum of twelve (12) inches below the outlet of the septic
tank so that water does not back up into the septic tank.
a.
To conveniently check the water level relative to the gravel surface,
a four (4) inch diameter perforated pipe shall be placed in the bottom
of the wetland, through the channel embankment, and then elbowed up
to the elevation of the top of the channel.
b.
Water level control shall be obtained by use of swivel standpipes
or collapsible tubing.
13.
Surface water shall be kept out of the wetland. This may be accomplished
by diverting runoff away from the wetland or constructing an earthen
berm around the wetland. Berms shall be a minimum of six (6) inches
above the surface of the porous media.
14.
Emergent plants shall be selected by the ability of the plants to:
root and grow in the wastewater rock environment, treat wastewater
to acceptable levels, produce biomass in amounts that can be controlled
and aesthetics. Reference may be made to Tables 614.9(a),(b) in selecting
desired plants.
|
Table 614.9(a)
Plant Growth Data After One Growing Season
| ||||||
|---|---|---|---|---|---|---|
|
Plant Species
|
Wet Weight
(lbs./sq.ft.)
|
Dry Weight
(lbs./sq.ft.)
|
Top Dry
|
Root Dry
|
Top/Root
|
Root Depth
(inches)
|
|
Softstem Bulrush
(Scirpus validus)
|
9.74
|
4.20
|
3.20
|
1.00
|
3.20
|
7.00
|
|
Horsetail
(Equisetum hyemale)
|
1.90
|
0.55
|
0.20
|
0.25
|
0.57
|
11.0
|
|
Water Iris
(Iris pseudacorus)
|
3.28
|
0.66
|
0.31
|
0.35
|
0.90
|
8.00
|
|
Pickerel Rush
(Pontederia cordata)
|
6.24
|
1.30
|
0.50
|
0.80
|
0.63
|
15.0
|
|
Arrowhead (Sagittaria latifolia)
|
2.25
|
0.35
|
0.17
|
0.18
|
0.94
|
10.0
|
|
Cattails (Typha latifolia)
|
7.89
|
3.00
|
1.90
|
1.10
|
1.73
|
8.00
|
|
Soft Rush (Juncus effusus)
|
3.00
|
1.05
|
0.65
|
0.40
|
1.62
|
18.0
|
|
Flowering Rush (Butomus umbellatus)
|
0.30
|
0.07
|
0.01
|
0.06
|
0.18
|
12.0
|
|
Table 614.9(b) Characteristics of Emergent Aquatic Plants
| ||||||
|---|---|---|---|---|---|---|
|
Plant Species
|
Bloom Date
|
Type of Bloom
|
Bloom Color
|
Plant Height
(Inches)
|
Growth Pattern
|
Initial Spacing
(Ft)
|
|
Softstem Bulrush
(Scirpus validus)
|
June — July
|
Oblong
Spikelets
|
Gray
|
40 — 60
|
Spreading
|
3
|
|
Horsetail
(Equisetum hyemale)
|
June — July
|
Oblong Spikelets
|
Brown
|
31 — 40
|
Spreading
|
3
|
|
Water Iris
(Iris pseudacorus)
|
May — Aug
|
Flower
|
White — Lt Blue
|
10 — 18
|
Bunches
|
2 — 3
|
|
Pickerel Rush
(Sagittaria latifolia)
|
July — Sept
|
Flower
|
Purple
|
10 — 18
|
Bunches
|
2
|
|
Arrowhead (Sagittaria latifolia)
|
June — July
|
Hanging Bulbs
|
Green — White
|
6 — 10
|
Spreading
|
3
|
|
Cattails
(Typha latifolia)
|
May — June
|
Oblong Spike
|
Spike Brown
|
48 — 72
|
Spreading
|
3
|
|
Soft Rush
(Juncus effusus)
|
June — July
|
Flower
|
Brown
|
18 — 30
|
Bunches
|
2
|
I.
Privy. A privy will be allowed only under limited conditions
and will not be recognized as a method of sewage treatment for a continuously
occupied dwelling, business or other structure. A privy will only
be considered for remote sites not served by a piped water source.
Plans and construction of a privy will need to meet the approval of
the Code Official.
1.
The privy shall be used to receive only human excreta and toilet
paper. The privy shall not be used as a depository for other wastes.
2.
A pit shall be provided for the privy. The sides of the pit shall
be curbed to prevent cave-in. If the pit has an earth bottom, the
bottom shall be at least three (3) feet above saturated soil conditions.
If this separation distance cannot be achieved in the location of
the privy, then the pit shall be liquid-tight.
3.
The pit shall be pumped out periodically by a licensed waste hauler.
At no time shall the pit contents be allowed to accumulate to within
one (1) foot of the pit top. The pit contents shall then be transported
and disposed into a community sewer system that is in compliance with
Chapter 644, RSMo.
4.
Both the pit and the privy shall be vented. Insect-proof openings
shall be placed in the walls, below the seat. A vent shall extend
from the underside of the seat board through the roof or up to a horizontal
vent open to the sides of the toilet. This vent must be flush with
the underside of the seat board and shall not extend down into the
pit. All vent openings to the outside shall be properly screened to
keep out insects. The top of the privy shall have a screened opening
on each side. It is preferable the opening be all the way around the
top of the privy in order to allow air to pass through and to carry
away any odors which may seep into the upper part of the structure.
If a crescent-shaped opening is cut into the door or wall of the privy,
it shall also be screened.
5.
The inside of the privy shall be of durable, smooth, non-absorbent
material. If wood is used, the inside of the structure shall be coated
with a polyurethane-type coating to minimize the penetration of liquids
and odors into the wood.
6.
A tight-fitting door, preferably with a self-closing feature, such
as a door spring, shall be used.
7.
A privy shall be set back from surface waters, buildings, property
lines and water supply wells the same distance as required for soil
treatment areas. This information may be found in Table 602.1.
8.
The privy shall be of sufficient capacity for the facility it serves,
but shall have at least fifty (50) cubic feet of capacity.
9.
Abandoned pits shall have the contents removed, transported and disposed
into a community sewer system that is in compliance with Chapter 644,
RSMo. This activity shall be performed by a waste hauler. The pit
shall then be filled with clean earth and slightly mounded to allow
for settling.
J.
Other Systems. Where unusual conditions exist, special systems
of treatment, other than those specifically mentioned in this code,
may be employed provided:
1.
Reasonable assurance of performance of the system is presented to
the Code Commission;
2.
The engineering design of the system is first approved by the Code
Commission;
3.
Adequate substantiating data indicate that the effluent will not
contaminate any drinking water supply, ground water used for drinking
water or any surface water;
4.
Treatment and treatment of the wastes will not deteriorate the public
health and general welfare;
5.
These systems comply with all applicable requirements of this code.
