All wastewater transmission facilities connecting directly or indirectly to County wastewater facilities shall be designed and constructed in accordance with the following minimum requirements. The County Agency may deny a connection permit for a transmission facility which is not in substantial compliance with these design and construction standards and conditions, or for which a satisfactory schedule cannot be agreed upon to bring it into compliance.
(a) General Regulations.
(1) All public sewer systems connecting directly or indirectly to a County sewer shall be approved by each municipality to be served by the proposed facility and by the County Agency having jurisdiction. County approval shall not be given until each municipality in which the proposed facility is to be physically located has had a reasonable opportunity to review and comment on the plans and specifications for the facility.
(2) If a sewer project is not under construction or a contract awarded within two years of approval by the County Agency, the approval shall be void, unless an extension of time has been approved by the County Agency.
(3) Construction shall not commence until all applicable local, State and Federal permits have been obtained.
(4) No new public sewer systems shall be placed in service until test results have been reviewed by the County Agency. Within two working days of receipt of those results, the County Agency will accept or reject the system. If the County Agency has not acted within that time, the project may be placed in service. The County Agency's approval is also subject to the receipt of acceptable as-built plans within ninety days of acceptance of the system.
(5) Any sewer which services two or more separate buildings or dwellings shall be a public sewer, unless the buildings are part of a singly-owned industrial complex or a public complex where future division of ownership is not anticipated.
(6) New construction shall be limited to separate wastewater transmission facilities, which outlet into a separate system. (See subsection (b) hereof.)
(7) Pumping systems will not be approved where, in the opinion of the County Agency, it is feasible to construct gravity sewer systems.
(8) For items not specifically covered herein, the design, in general, shall conform to the "Recommended Standards for Sewage Works" of the Great Lakes-Upper Mississippi River Board of State Sanitary Engineers, more commonly referred to as the "10-State Standards".
(b) Design Flows.
(1) Wastewater transmission systems shall be designed on the basis of an average flow of 100 gallons per capita per day, unless another flow is specifically approved by the County Agency.
(2) Sewers shall be designed to carry, when running full, the flows specifically approved by the County Agency.
(3) Calculations showing the basis of design shall be submitted to the County Agency, except for service areas which are to be served by eight-inch sewers.
(c) Sewers.
(1) General regulations.
A. Any generally accepted material for sewers will be given consideration, but the material selected should be adapted to local conditions, such as character of industrial wastes, possibility of septicity, soil characteristics, exceptionally heavy external loadings, bedding, abrasion and similar problems.
B. Sewer joints and materials shall be designed to minimize infiltration and to prevent the entrance of roots.
C. All sewer systems shall be designed so as to limit infiltration to 200 gallons per inch of pipe diameter per mile of sewer per day. All points of future connection to the system shall be sealed to meet leakage restrictions and testing requirements.
D. Sewers shall be sufficiently deep so as to prevent freezing. The minimum depth to the top of pipe shall be forty-two inches.
E. Sewers shall be properly vented.
F. A bulkhead shall be installed at each outlet to an existing system, and shall not be removed until the new sewer system has been accepted by the County Agency.
G. Sewers shall be laid at least ten feet, horizontally, from any existing or proposed water main. A minimum vertical clearance of eighteen inches shall be maintained between the top of the sewer and the bottom of the water main under which it crosses. Vertical clearance of less than eighteen inches or crossing of a sewer over a water main will require that special measures be taken to prevent contamination of the water supply, such as encasement of the sewer.
H. No connections from footing drains, sump pumps, roofleaders, etc., shall be made to the system.
I. Tree plantings, for restoration purposes, shall not be permitted within fifteen feet of the center line of new or repaired sewers.
(2) Public sewers.
A. Sewers shall be a minimum of eight inches in diameter.
B. Sewers shall be designed for mean velocities, when flowing full, at design flows of not less than 2.0 feet per second, based on Kutter's formula using an "n" value of 0.013. Use of other "n" values may be permitted if deemed justifiable on the basis of research or field data presented.
C. Sewers shall be designed with a uniform line and grade between manholes.
D. When a smaller sewer joins a larger one, the invert of the larger sewer shall be lowered at least enough to maintain the 0.8 depth point of both sewers at the same elevation.
E. Where velocities greater than fifteen feet per second may be attained, special provision shall be made to protect against scouring and thrust displacement.
(3) Building sewers.
A. A separate building sewer shall be provided for each building or dwelling.
B. The building drain connection to the building sewer shall be sealed by an approved method and encased in concrete to provide a water tight seal.
C. Building sewers shall be designed and installed so as to limit infiltration to 200 gallons per inch of sewer diameter per mile of sewer per twenty-four hours, and local public authorities shall conduct testing programs which will assure substantial conformance to this infiltration requirement.
D. Building drain inlets shall be sealed by an approved method during construction and seals shall not be removed until plumbing is carried to the first floor, basement walls are backfilled, the footing drain system is operating, and such other precautions have been taken as are necessary to insure that no storm or ground water will enter the sanitary sewer.
E. No wyes, cleanouts or similar appurtenances shall be connected to a building sewer or a building drain outside the walls of the building except where specifically required by local building codes. Where so required, such appurtenances shall be sealed by an approved method so as to insure that no storm or ground water will accidentally or intentionally be admitted through the appurtenances.
F. No trap shall be installed in the building drain between the main vent and the building sewer.
G. The minimum grade of building sewers shall be one foot per 100 feet (1.00%).
H. Building sewers shall not be connected to manholes except from the upstream side of a terminal manhole.
(d) Manholes.
(1) Manholes shall be installed at the end of each line; at all changes in grade, size, or alignment; and at all intersections. Spacing between manholes shall not exceed 400 feet on runs of sewer forty-eight inches in a diameter or less. On runs of sewer greater than forty-eight inches in diameter, spacing of manholes shall be approximately 100 times the diameter of the sewer.
(2) Manholes constructed in road rights-of-way shall be located away from open ditch drainage systems so that no portion of any manhole protrudes into the drainage ditch. If necessary, the open ditch system shall be relocated or enclosed adjacent to the manhole to provide complete cover around the manhole.
(3) Manhole construction shall be precast concrete with modified grooved tongue joints and gasket, unless otherwise approved by the County Agency.
(4) Manhole steps shall be constructed of cast iron, unless otherwise approved by the County Agency.
(5) A standard drop connection shall be provided for a sewer whose invert is at an elevation of eighteen inches or more above the spring line of the existing sewer. Where the difference in elevation between the invert of the incoming sewer and the manhole invert is less than eighteen inches, the manhole should be filleted to prevent solids deposition.
(6) The minimum inside diameter of manholes shall be forty-eight inches, and drop connections or other permanent devices (except manhole steps) which would reduce any clear inside dimension to less than forty-eight inches shall not be installed in a manhole.
(7) There shall not be less than ten inches of undisturbed concrete between adjacent openings in the manhole nor shall more than fifty percent of the circumference along any horizontal plane be removed without special reinforcing or strengthening of the walls as approved by the County Agency.
(8) Perforated manhole covers shall not be used; where venting is required, vent pipes shall be installed.
(9) Lock-down pressure-tight frames and covers shall be used in the following locations:
A. Lock-down pressure-tight covers shall be required in flood plain areas located below 100-year flood elevation.
B. Manholes in easements which are not parallel and adjacent to public rights-of-way shall be constructed with lock-down pressure-tight covers to limit storm water drainage into the sanitary sewer system and to prevent dumping of other deleterious matter into the manholes.
(10) The flow channel through manholes shall be made to conform in shape and slope to that of the sewers.
(11) Control manholes required under this chapter shall be constructed in accordance with the standards of the County Agency.
(e) Pumping Stations.
(1) Municipal.
A. General regulations.
1. The maximum discharge rate shall not exceed the flows indicated in the sanitary sewer design approved by the County Agency.
2. Provision of an emergency power supply for pumping stations shall be made, and may be accomplished by connection of the station to at least two independent public utility sources, or by provision of portable or in-place internal combustion engine equipment which will generate electrical or mechanical energy, or by the provision of portable pumping equipment.
3. Pumping stations shall be equipped with a high water alarm.
4. Where, in the opinion of the County Agency, the operation of a pumping station becomes critical to the operation of the County wastewater facilities, the County Agency shall assume jurisdiction for operation and maintenance of the pumping station.
B. Master pumping stations.
1. Master pumping stations with capacities in excess of fifty GPM shall be equipped with an approved recording totalizing flowmeter and a wet well recorder. Copies of flow records shall be forwarded to the County Agency at the end of each month’s operation. Copies of the wet well level recorder shall be forwarded to the County Agency as requested.
2. No change which will increase the authorized pumping capacity of the master pumping station may be made without the written consent of the County Agency.
3. Master pumping stations exceeding 250 GPM capacity or ten percent of the hydraulic capacity of the treatment facility shall be designed for variable speed operation.
4. Design period shall be as follows:
a. "Variable Speed" pumping stations shall have a maximum design period of twenty years, provided that the pumping system's lowest effective pumping rate, which does not harm the pumps, is no greater than the maximum allowable rate of wastewater flow anticipated five years from the time the station is placed in service.
b. "Constant speed" pumping stations shall have a maximum design period of five years from the time the station is placed in service. Provisions for increasing capacity in five-year increments may be incorporated in the original construction.
(2) Private.
A. Pumping stations having capacity in excess of fifty GPM shall comply with all requirements of municipal pumping stations.
B. The municipality shall keep records of all stations of fifty GPM or less, to be furnished to the County Agency on request.
C. Where, in the opinion of the County Agency, private pumping systems create a burden on the wastewater facilities, the Agency will require the Municipality to install public facilities to correct the situation.
(f) Force Mains.
(1) At design average flow, a cleansing velocity of at least two feet per second shall be maintained.
(2) An automatic air relief valve shall be placed at high points in the force main to prevent air locking.
(3) If disposal facilities are available, blow-off or flushing arrangements are desirable at low points in the force main.
(4) Access points for maintenance shall be placed along the force main at distances not exceeding 500 feet.
(5) A velocity reducing device shall be required at the juncture of the force main with the gravity sewer.
(6) Force mains should enter the gravity sewer system at a point not more than twenty-four inches above the flow line of the receiving manhole or shall have a drop connection approved by the County Agency.
(g) Inverted Siphons.
(1) Inverted siphons shall have not less than two barrels.
(2) The minimum pipe size shall be six inches.
(3) The terminal manholes shall have adequate clearances for rodding and shall be equipped with the necessary appurtenances for convenient flushing and maintenance.
(4) The inlet and outlet details shall be arranged so that normal flow is diverted to one barrel, and so that either barrel may be taken out of service for cleaning.
(5) Sufficient head shall be provided and pipe sizes selected to obtain a velocity of at least 3.0 feet per second for average daily flows at ultimate design.
(6) The smallest pipe shall be designed to obtain a minimum velocity of 3.0 feet per second for the maximum daily flow anticipated five years from installation.
(h) Testing. The County Agency shall be notified one working day in advance of all post-construction testing. The following tests shall be performed by qualified personnel approved by the County Agency and a written report furnished to and approved by the County Agency prior to placing any public facility in service:
(1) Sewer systems.
A. Visible and audible checks shall be made of the sewers and manholes and all leaks repaired prior to testing.
B. All sewer lines, which are not inspected by walking or crawling through the sewer, shall be televised for misalignment, infiltration, for defective pipe or joints and for debris. For a point of clarity, pipe size thirty inches in diameter and smaller shall be televised.
C. Leakage tests shall be conducted on all new sewer lines and existing lines which have not been previously approved.
D. All sewers shall be subjected to air, infiltration or exfiltration tests, or a combination of the same, prior to acceptance by the County Agency. All sewers over twenty-four inches in diameter shall be subjected to infiltration tests before initial start-up. All sewers twenty-four inches in diameter or smaller, where the ground water level above the top of the sewer is over seven feet, shall be subjected to infiltration tests. All sewers twenty-four inches in diameter or less, where the ground water level above the top of the sewer is seven feet or less, shall be subject to air tests or exfiltration tests. If an exfiltration test is performed, the maximum exfiltration rate shall be the same as that permitted from infiltration. For the purpose of exfiltration testing, the internal water level shall be equal to the external water level plus seven feet as measured from the top of pipe, and the elevation must be at least as high as the highest house service.
E. Maximum allowable infiltration shall not exceed 200 gallons per inch of diameter per mile of pipe between manholes per twenty-four hours for any section of the system and shall include the infiltration from all manholes and other appurtenances.
F. The procedure for air testing of sewers shall be as follows:
All house leads shall be properly plugged and blocked to withstand the air pressure. The sewer line shall be tested in increments between manholes. The line shall be cleaned and plugged at each manhole. Such plugs shall be designed to hold against the test pressure and shall provide an airtight seal. One of the plugs shall have an orifice through which air can be introduced into the sewer. An air supply line shall be connected to the orifice. The air supply line shall be fitted with suitable control valves and a pressure gauge for continually measuring the air pressure in the sewer. The pressure gauge shall have a minimum diameter of three and one-half inches and range of 0-10 PSIG. The gauge shall have minimum divisions of 0.10 PSIG and an accuracy of +/- 0.04 PSIG.
The sewer shall be pressurized to 4.0 PSIG greater than the greatest back pressure caused by groundwater over the top of the sewer pipe. At least two minutes shall be allowed for the air pressure to stabilize between 3.5 and 4.0 PSIG. If necessary, air shall be added to the sewer to maintain a pressure of 3.5 PSIG or greater.
After the stabilization period, the air supply control valve shall be closed so that no more air will enter the sewer. The sewer air pressure shall be noted and timing for the test begun. The test shall not begin if the air pressure is less than 3.5 PSIG, or such other pressure as is necessary to compensate for ground water level.
The time required for the air pressure to decrease 1.0 PSIG during the test shall be in accordance with the standards of the County Agency.
Manholes on sewers to be subject to air tests shall be equipped with a half-inch diameter galvanized capped pipe nipple extending through the manhole wall, three inches into the manhole and at an elevation equal to the top of the sewer pipe. Prior to the air test the ground water elevation shall be determined by blowing air through the pipe nipple to clear it and then connecting a clear plastic tube to the pipe nipple. The tube shall be suspended vertically in the manhole and the ground water elevation determined by observing the water level in the tube. The air test pressure shall be adjusted to compensate for the maximum ground water level above the top of the sewer pipe to be tested. After all tests are performed and the sewer is ready for final acceptance, the pipe nipple shall be removed and the hole in the manhole wall shall be plugged with hydraulic cement.
If a sewer fails to pass any of the previously described tests, the contractor shall determine the location of the leaks, repair them and retest the sewer. The tests shall be repeated until satisfactory results are obtained.
(2) Pumping systems. Tests shall be conducted to verify performance curves of each pumping device installed in the system.
(3) Force mains. When practicable, tests shall be made on sections between valves, or sections not exceeding 2,000 feet in length. Dead ends, bends and other fittings shall have a firm foundation and be securely blocked against the trench walls before testing or completing the backfill as specified.
Before applying test pressure, all air shall be expelled from the pipe. If necessary to accomplish this, taps shall be made at the points of highest elevation, and such openings subsequently closed, prior to testing, with tight threaded brass plugs.
Test pressure shall be maintained at fifty pounds per square inch, by pumping water into the pipe, for a period of at least one hour, and for such longer time as may be required to permit a thorough examination to be made of all exposed joints in the section of main being tested.
Leakage, as measured by the quantity of water pumped into the pipe to maintain the test pressure of fifty pounds per square inch during the test period, shall not exceed a rate of fifty U.S. gallons per inch of diameter of main per mile of pipe in twenty-four hours.
(i) Plans.
(1) Five sets of plans shall be submitted for approval for all wastewater transmission facilities connecting directly or indirectly to County sewers.
(2) The following data shall be incorporated in the plans:
A. Each set of plans shall be approved and signed by the officially designated Municipal engineer, who shall be a registered civil engineer.
B. Each set of plans shall bear the seal of the registered civil engineer who is responsible for the plans.
C. A listing of all sewer lengths and diameters for the proposed sewer shall accompany the plans.
D. A location map indicating 1/4 section in which the project is located.
E. When more than one sheet is required for the plan, a small scale overall plan shall be shown.
F. Two bench marks shall be indicated on each plan sheet.
G. In instances where the County Agency has no record of the existing sewer to which a proposed sewer is to be connected or where the existing sewer is not shown in accordance with previously approved plans, as-built plans of the existing sewer and evidence of acceptable leakage tests shall also be submitted for approval.
H. All existing sewer inverts must be field measured and shall be so designated on the plan.
I. A profile, including inverts, gradient, length and drop connections, shall be shown for each run of sewer or force main.
J. Existing and proposed utilities shall be shown on the plan and the profile.
K. Manholes shall be numbered on the plan and the profile.
L. The locations of existing or proposed stoppers and bulkheads shall be indicated on the plan.
M. Proposed or existing curb or sidewalk grades of streets adjacent to the sewer shall be shown on the profile.
N. Basement grades shall be shown for existing and proposed houses where the sewer is less than ten feet deep or a note stating no basements, or the method of serving basements shall be included.
O. Allowable types of pipe, joints and stoppers for public and building sewers shall be indicated on the plan.
P. Dead-end sewers shall be designated as follows: "To facilitate future construction only, no house leads allowed until terminus manhole is constructed."
Q. An easement shall be designated on the plan for each run of public sewer not in the public right-of-way. The minimum easement shall be twelve feet; however, the rear easement on subdivision lots may be reduced to six feet where there is no contiguous subdivision.
R. Details of pipe bedding, building sewers, drop connections, bulkheads, manholes, manhole covers, and other appurtenances shall be submitted with the plan.
S. The following notes shall appear on the plan:
1. No connection receiving storm water, surface water, or ground water shall be made to sanitary sewers.
2. Infiltration for any section of sewers between manholes shall not exceed 200 gallons per inch of diameter per mile per hour.
3. All elevations are based on Wayne County datum (USCGS).
4. No footing drains shall be connected to the building sewer.
5. Differential of excavation around existing manholes shall not exceed six feet.
(j) Existing Sewer Systems.
(1) Alterations to existing system.
A. General. No work shall be performed on existing sewer systems which would change the capacity of the system or would result in nonconformity with this chapter, except by written permission of the County Agency.
B. Manholes. When it is necessary to excavate adjacent to manholes or similar structures, the excavation shall extend around the entire perimeter, so that the differential of excavation on opposite sides of the structure does not exceed six feet, unless written permission is obtained from the County Agency.
C. Siphons. Siphons shall not be constructed in existing sewers, except where it can be demonstrated to the satisfaction of the County Agency that such siphons will not have a detrimental effect on the maintenance of the sewer or the hydraulic gradient of the system.
(2) Approval of existing systems as public systems.
A. Sewer systems not having been previously approved as public sewers may be accepted as public sewers, provided they meet all requirements of this chapter.
B. The County Agency shall perform or designate a registered engineer to perform such tests on the sewer as it deems necessary. All costs of performing such tests shall be borne by the owner of the facility.
(k) Combined Sewer Systems.
(1) Existing combined sewer systems will be permitted to continue in service subject to the following restrictions:
A. Connections from the combined system shall be through adjustable regulators which limit flow into the intercepting sewer to 325 percent of the average daily dry weather flow rate, unless otherwise permitted by the County Agency.
B. The County Agency shall have jurisdiction for the operation and maintenance of all regulators.
C. The Municipality shall report water consumption by regulator districts.
D. The Municipality shall agree to pay charges for operation, maintenance and updating of regulators, as established by the County Agency.
E. New construction shall not be subject to the design and construction requirements pertaining to separate wastewater transmission systems.
(2) Sanitary sewer systems may not outlet into existing combined sewers except when the cost of a separate sanitary intercepting sewer is regarded by the County Agency to be disproportionate to the cost of the sanitary system and when an approved preliminary plan for a sanitary outfall or sewer separation is on file with the County Agency.
(Ord. 712. Passed 2-14-01.)