Paulding County › Unified Development Ordinance
Title 3 — Development Regulations, Chapter 470 — Wastewater Design and
§ 470-10
General
470-10.01 This section provides the minimum guidelines for the design of gravity sanitary
sewer collection systems. The method of design and/or construction shall be according to these Design and Construction Standards and Specifications and the following:
A.Recommended Standards for Sewage Works (Ten State Standards) Latest Edition
B.Georgia Environmental Protection Division State of Georgia Regulations for Water and Sewerage Works, Latest Edition
C.Georgia Manual for Erosion and Sediment Control, latest edition
D.Georgia Stormwater Management Manual Volumes 1 & 2, latest editions
E.American Association of State Highway and Transportation Officials (AASHTO) Green Book, Latest Edition
F.American Concrete Institute (ACI) Standards, latest editions
G.American Society of Testing Materials (ASTM)
H.American National Standards Institute (ANSI)
I.American Water Works Association (AWWA)
J.Manual on Uniform Traffic Control Devices, latest editions
K.Occupational Safety and Health Administration (OSHA)
L.Applicable Federal, State and Local Requirements
470-10.02 In the event of conflicts among the various sources cited above, the most stringent
criteria shall take precedence.
470-10.03 Sanitary sewers shall be designed as separate sanitary sewers only. Rainwater
from roofs, streets and other areas and groundwater from foundation drains are excluded from connecting to the sanitary sewer system. Connections from sanitary sewers to storm sewers shall not be permitted.
§ 470-20
Design Flows
470-20.01 The criteria listed herein are not intended to cover all aspects of design, but rather
to mention the basic guidelines and those particulars that are required by the Paulding County Department of Water, Sewer and Environmental Services. For more detailed criteria, the reader should refer to standard references such as "Ten States Standards," Georgia EPD Regulations, Water Pollution Control Federation Manual of Practice No. FD-5, and other available literature. Each system component shall be designed to meet certain flow requirements. Sanitary sewers shall be designed as separate sanitary sewers only in which rainwater from roofs, streets and other areas and groundwater from foundation drains are excluded.
Overflows from sanitary sewers to storm sewers are not permitted.
§ 470-30
Sizing of Gravity Sewer Mains
470-30.01 Major Outfalls.
The size of major outfall sewers or extensions to such mains, throughout the system shall be in accordance with Paulding County Wastewater Master Plan, latest revision on the Paulding County Government Web Site. Contact the Paulding County Water System Engineering Manager for additional information and guidance with regard to this requirement.
470-30.02 Collector Sewers.
All gravity sewer mains shall be designed to convey the Design Peak Flow at a flow depth not to exceed 67% of the pipe inside diameter or less than 0.6 inches, and at a minimum self-cleansing velocity of 2.0 feet per second. Gravity sewer mains intended for public use and Paulding County Water System operation and maintenance shall be sized to meet these hydraulic guidelines with the minimum pipe size being eight-inches in diameter.
470-30.03 Sizing Factors.
A.The sanitary sewer system should be designed for the estimated ultimate tributary population. Tributary population is considered to be all areas upstream of the discharge point of the system being designed. Sewers will be designed and installed to the uppermost property line of the development being served. Consideration should be given to the maximum anticipated capacity of the developments projected flow.
B.In determining the required capacities of sanitary sewers, the following factors should be considered:
A.Maximum hourly sewage flow;
B.Additional maximum sewage or waste flow from industrial plants;
C.Ground water infiltration;
D.Topography of the area; and
E.Depth of excavation
C.New sanitary sewer systems shall be designed on the basis of an average daily flow of sewage of not less than 350 gallons per household per day. Normally all sanitary sewers shall be designed with a peaking factor of not less than four and this may be increased as required by the Water System. Peak factors will be higher for smaller basins. Sanitary sewers should be designed to carry the peak flow when flowing at a depth of ⅔-pipe diameter.
1.When deviation from the foregoing per capita rates are demonstrated, a description of the procedure used for design shall be included on the approved construction drawings.
2.No sewer main shall be less than eight inches and no service lateral shall be less than six inches.
3.When a small sewer is connected to a larger one, the connection shall be made by matching the crowns of both sewers to same elevation.
D.Upsizing of an outfall sanitary sewer may be needed when a owner/developer is submitting plans for a development in an area where the main outfall through the development requires a larger size to meet the requirements of the Paulding County Wastewater Master Plan. Paulding County Water System will require the sewer size indicated in the Wastewater Master Plan to be installed by the owner developer. In these cases, Paulding County Water System may enter into a pipe swap agreement in which the pipe material is provided for the outfall. The Paulding County Wastewater Master Plan may be found on the government website.
470-30.04 Depth Requirements.
A.Any sewers installed under pavement shall be sufficiently deep to provide six feet of cover at the inlet end of all service laterals at the street right-of-way, and over any part of the main or service within the street right-of-way.
B.Any sewers on off-street easements shall have a minimum of four feet of cover. In extraordinary circumstances where there is no other alternative, ductile iron pipe shall be used where there is less than four feet of cover with approval by the Water System Engineering Manager. Filling over the pipe to obtain minimum cover is not allowed, if the fill will impede the natural flow of surface water or will cause an erosion problem.
§ 470-40
Gravity Sewer Mains Pipe Slope Requirements
470-40.01 Discussion.
A.The major items for consideration in the regulation of gravity sewer pipe slopes are carrying capacity at peak flow and self-cleansing velocity. The inability to convey peak flow results in system surcharging and potential sanitary sewer overflows. The lack in the development of self-cleansing velocity, at least during the flows diurnal peak, results in solids deposition, system odors, and the eventual reduction in pipe capacity leading to blockages and overflows.
B.An additional consideration in the Paulding County jurisdictional area is wastewater piping system detention time. Lengthy wastewater detention or travel time through gravity piping systems encourages the development of corrosive and odorous gases that damage piping infrastructure, cause odor complaints and increase the cost of system operation by requiring the addition of chemicals to inhibit or mitigate the effects of aging wastewater. Therefore, design of gravity sewer systems in this standard shall stress the development of self- cleansing velocities as the most practical and effective method of minimizing wastewater detention times in sewer mains.
C.The criteria listed herein is not intended to cover all aspects of design, but rather to mention the basic guidelines and those particulars that are required by the Paulding County Water System. For more detailed criteria, the reader should refer to standard references such as "Ten States Standards," Georgia EPD Regulations, Water Pollution Control Federation Manual of Practice No. FD-5.
D.All gravity sewer mains shall be designed to convey the Design Peak Flow at a minimum self-cleansing velocity of 2.0 feet per second.
E.Paulding County Water System’s pipe slope design requirements are developed to provide a range of acceptable pipe slopes based on good hydraulic engineering practice using “projected” pipe flow rates based on ERU’s and peaking factors.
470-40.02 Gravity Sewer Main Grades.
A.All sewers shall be so designed and constructed to give mean velocities, when flowing full, of not less than two feet per second based on Manning's Formula using an "n" value of 0.013. The following are the minimum slopes that should be provided; however, slopes greater than these are desirable:
Table 470.1
| Pipe Size (Inches) | Minimum Slope per 100 Feet |
|---|---|
| 6 | 1.00 |
| 8 | 0.40 |
| 10 | 0.29 |
| 12 | 0.22 |
| 14 | 0.17 |
| 15 | 0.15 |
| 16 | 0.14 |
| 18 | 0.12 |
| 21 | 0.10 |
| 24 | 0.08 |
| 27 | 0.07 |
| 30 | 0.06 |
| 36 | 0.05 |
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§ 470-50
Material Specifications
470-50.01 General.
A.The owner/developer shall furnish gravity sewer piping systems in accordance with the material specifications detailed below. All references to industry standards (ASTM, ANSI, AWWA, etc.) shall be to the latest revision unless stated otherwise. All materials shall be new. These material specifications include a list of acceptable manufacturers for the various wastewater system components as shown in the preferred manufacturers list. The owner/developer may choose freely from the manufacturers list and material submittals for such items are not required. Only products and materials from the preferred manufacturer's lists herein may be used in the work.
B.Any item required but not specified herein, or any product or manufacturer other than those listed will be considered a substitution. Material submittals are required for such items. Substitutions will not be allowed without the prior written approval from Paulding County Water System. Substitutions, if allowed, shall meet all criteria of the detailed specifications. The burden of proof of compliance for any proposed substitution rests with the Contractor / Developer / Owner. The Paulding County Water System will determine the acceptance of a proposed substitution and such decisions will be final.
C.The type, class, grade, and alignment of sewer pipe may be changed only at manholes.
D.Gravity sewer mains up to 10 inches in diameter shall be Ductile Iron Pipe (DIP), Polyvinyl Chloride (PVC) and C900. Gravity sewer mains over 10 inches in diameter shall be Ductile Iron Pipe (DIP). Paulding County Water System reserves the right to disallow any manufacturer that does not have a consistent, long-term record of quality control and successful product performance. Ductile Iron Pipe shall be used where certain conditions exist. See Table 470.2.
Table 470.2
| Pipe Size (Inches) | Material | Depth |
|---|---|---|
| 6 | DIP / PVC | 6' < PVC < 14’ DIP any depth |
| 8 | DIP / PVC | 6' < PVC < 14’ DIP any depth |
| 10 | DIP / PVC | 6' < PVC < 14’ DIP any depth |
| 12 and larger | DIP | DIP any depth |
1.Over or under all storm sewers.
2.From manhole to manhole when connected to drop manholes greater than two feet.
3.From manhole to manhole when crossing water mains.
4.Under all stream crossings.
5.With less than six feet of cover or over 14 feet of cover.
6.With 15% or greater slope.
7.Inside casings.
8.On all force mains.
9.Where clearances between sanitary sewer and storm sewer are two feet or less
10.As site specific conditions warrant.
B.All DIP shall be subject to inspection and approval by the Water System Engineering Technician after delivery. No broken, cracked, imperfectly coated or otherwise damaged or unsatisfactory pipe or fittings shall be used. The pipe interior shall be Polybond, Polyline, polyurethane or Protecto 401 ceramic epoxy lined with a minimum thickness of 40 mm. The exterior shall be seal coated with an approved bituminous seal coat in accordance with AWWA C151.
C.Unless otherwise shown on the approved construction Drawings, DIP shall be manufactured in accordance with AWWA C150 and 151. All pipe, except specials, shall be furnished in standard lengths of 18 to 20 feet. Sizes will be as shown on the approved construction Drawings. All pipe shall have a minimum pressure rating as indicated in Table 470.3, and corresponding minimum wall thickness, unless otherwise specified or shown on the approved construction Drawings. Pipe wall thickness shall be determined based on dead loads indicated on the approved construction Drawings and the anticipated live loads, assuming a minimum HS 20 live load.
Title 3: Chapter 470
Table 470.3
| Pipe Diameter (inches) | AWWA C- 150 Laying Condition | Pressure Class (psi) | Maximum Depth of Cover (ft) |
|---|---|---|---|
| 8 | Type 1 | 350 | 3-16 |
| 8 | Type 4 | 350 | 16-34 |
| 10-12 | Type 1 | 350 | 3-10 |
| 10-12 | Type 4 | 350 | 10-28 |
| 10-12 | Type 5 | 350 | 28-44 |
| 14-20 | Type 4 | 250 | 3-22 |
| 14-20 | Type 5 | 250 | 22-30 |
| 14-20 | Type 5 | 350 | 30-41 |
| 24-30 | Type 4 | 250 | 3-19 |
| 24-30 | Type 5 | 300 | 19-27 |
| 24-30 | Type 5 | 350 | 29-33 |
| 36-42 | Type 4 | 300 | 3-20 |
| 36-42 | Type 5 | 350 | 20-32 |
2.Flanged elbow fittings shall be ANSI pattern using short radius elbows except where noted differently on the Drawings. Special fittings, ductile iron wall pipes and sleeves shall conform to the dimensions and details as shown on the approved construction Drawings.
E.Joints for Ductile Iron Pipe and Fittings
1.General.
(a)Joints for ductile iron pipe and fittings shall be mechanical joint, flanged joint or push-on joint as shown on the approved construction drawings or specified herein.
Title 3: Chapter 470
(b)Unless otherwise shown on the approved construction drawings, specified or directed, all ductile iron pipe laid underground shall be joined using push-on type joints. Pipe joints shall be push-on joints conforming to AWWA C111, unless specified otherwise on plans.
(c)In all cases, gaskets shall be made of material that will not be damaged by the fluid being transported nor by the environment in which the pipe is installed.
(d)Provide the necessary bolts for connections. All bolts and nuts shall be threaded in accordance with ANSI B1.1, Coarse Thread Series, Class 2A external and 2B internal fit. All bolts and nuts shall be made in the USA.
2.Mechanical Joints.
(a)Joints shall conform to AWWA C111/ANSI A21.11.
(b)Bolts and nuts shall be Tee Head Bolts and nuts of high strength low-alloy steel in accordance with ASTM A 242 to the dimensions shown in AWWA C111/ANSI A21.11.
(c)Gaskets shall be in accordance with AWWA C111/ANSI A21.11 and shall be constructed of plain rubber.
(d)Mechanical joint glands shall be ductile iron.
3.Push-On Joints. Push-on joints and gaskets shall conform to AWWA C111/ANSI A21.11. See list of acceptable manufacturers.
4.Restrained Joints. Inside of casings, the sewer line joints shall be slip joint restrained by using U.S. Pipe “Field-Lok” gaskets or approved equal.
F.Protective Inner Linings: Pipes shall be coated on the inside with Protecto 401 protective liner or approved equivalent.
G.Polyethylene Encasement: Polyethylene film shall meet the requirements of AWWA C 105.
H.Pump Station - Wall Sleeves and Wall Pipes
1.Where piping passes through concrete structures, furnish and install wall sleeves unless wall pipes or other provisions are specifically shown on the Drawings. Wall sleeves shall be accurately located and securely fastened into position before concrete is poured.
2.Wall Sleeves.
(a)For pipe sizes smaller than three-inches, wall sleeves shall be steel oversize sleeves furnished with a full circle, integral, or continuously welded waterstop collar. The sleeve seal shall be the mechanically expanded, synthetic rubber type. Provide all associated bolts, seals and seal fittings, pressure clamps, or plates necessary to achieve a watertight installation. Sleeves shall extend the full thickness of the concrete. Sleeves and seal shall be Link Seal.
(b)For pipe sizes larger than three-inches, wall sleeves shall be ductile Title 3: Chapter 470 iron mechanical joint wall sleeves. Unless specified or shown otherwise for a specific situation, wall sleeves shall be mechanical joint bell-plain end type with waterstop/thrust collar. The collar shall be capable of withstanding a thrust force caused by a 250 psi dead end load from either direction on that size pipe. Sleeves shall be constructed with studs and mechanical joint retainer gland on the air side of the concrete structure. Provide retainer gland where shown on the Drawings. Where the concrete structure is exposed to dirt on one side and is wet on the other side, construct with studs and glands on the dirt side. See list of acceptable manufacturers.
3.Wall Pipes.
(a)Wall pipes shall be either ductile iron with integral waterstop/thrust collar or centrifugally cast ductile iron with a continuously welded waterstop/thrust collar. The welded on collar shall be attached to the pipe by the manufacturer. The collar shall be capable of withstanding a thrust force caused by a 250 psi dead end load from either direction on that size pipe. Wall pipes shall be furnished uncoated on the outside and cement lined on the inside. Wall pipes shall be flange end type.
(b)Wall pipes shall be cast and/or fabricated and lined in one manufacturer's facilities and delivered to the job site ready for use.
470-50.03 Polyvinyl Chloride (PVC) Gravity Sewer Pipe
A.Pipe and Fittings. All PVC pipe and fittings through 10 inches shall meet the requirements as specified under ASTM D3034. All pipe and fittings shall be suitable for use as a sanitary sewer conduit. Bell joints shall consist of an integral wall section with elastomeric gasket joint that provides a watertight seal. Standard laying lengths shall be 13.0 – 18.0 feet (+/- 1 inch). The pipe shall be capable of passing all tests that are detailed in this specification.
Minimum wall thickness for pipe through 10 inches in diameter shall be as specified under SDR 35 in ASTM D3034. PVC sewers with more than 12 feet of cover may require wall thicknesses greater than SDR 35 or T-1. PVC is not allowed for sewers greater than 10 inches in diameter or more than 14 feet of cover or less than six feet of cover.
B.Each length of pipe shall be marked with the manufacturer’s name, trade name, nominal size, class, hydrostatic test pressure, manufacturer’s standard symbol to signify it was tested, and date of manufacture. Each rubber ring shall be marked with the manufacturer’s identification, the size, the year of manufacture, and the classes of pipe with which it can be used.
C.All PVC fittings and accessories shall meet the requirements specified under ASTM D3034 or F679 and shall be manufactured and furnished by the pipe supplier. They shall have bell and/or spigot configurations compatible with that of the pipe and shall have an equivalent wall thickness.
D.Pipe and Fittings Tests. All shipments of pipe and/or fittings shall be tested and certified to by an approved independent testing laboratory. Up to 0.5% of the number of pipe of each size furnished shall be tested, except that in no case shall less than two specimens be tested. The owner/developer shall be responsible for providing three certified copies of the test results obtained by the testing laboratory under provisions for testing in the applicable test procedures listed below. Testing shall be done at the owner/developer ’s expense, and no pipe shall be installed until the test results are approved by the Water System.
E.Pipe Stiffness. Minimum “pipe stiffness” (F/Y) at 5% deflection shall be 46 PSI for all sizes, when tested in accordance with ASTM Standard Method of Test D2412, to determine the “External Loading Properties of Plastic Pipe by Parallel Plate Loading.” There shall be no evidence of splitting, cracking or breaking at a deflection of up to 30% of the original diameter.
F.Extrusion Quality. There shall be no evidence of flaking, swelling or disintegration when the pipe material is tested in accordance with ASTM D2152, “Quality of Extruded Poly (Vinyl Chloride) Pipe and Molded Fittings by Acetone Immersion.”
G.Joint Tightness. Pipe and fitting joints shall comply with ASTM D3212 for “Joints for Drain and Sewer Plastic Pipes Using Flexible Elastomeric Seals.”
Joint assemblies shall not leak when subjected to both an internal and external hydrostatic test at equivalent pressures of 10.8 psi gauge for a period of one hour. Pipes shall be tested in straight alignment, axially deflected position, and by shear load test as otherwise defined in paragraphs 7.2, 7.3 and 7.4 of ASTM D3212.
H.Impact Resistance. Pipe shall comply with impact resistance test conducted in accordance with ASTM D2444, “Test for Impact Resistance of Thermoplastic Pipe and Fittings by Means of a Tup (Falling Weight).”
I.Installation. PVC pipe will be installed in accordance with ASTM D2321 (latest revision). Class “B” bedding is the minimum bedding requirement for PVC pipe. In any area where the pipe is below existing ground water level or below the 100-year flood plain level, the owner/developer will embed PVC pipe in sand or graded gravel.
J.Deflection Limit. Vertical deflection of installed pipe shall not exceed 5% of the undeflected diameter as defined in ASTM D3034. Upon completion of the pipe laying, and at least 30 days after installation (to allow for settling), the pipe will be tested for conditional acceptance (subject to the 24-month maintenance period). The test shall be performed by the owner/developer’s contractor pulling a mandrel of specified dimensions through the pipeline under the supervision of a water system engineering technician.
470-50.04 Steel Casing Pipe.
A.Steel casing pipe shall be manufactured from steel conforming to ASTM A 139, Grade B and be new and unused with a minimum yield strength of 35,000 psi.
See Standard Detail Sheet G-5 for thickness. It shall be fully coated on the exterior and interior with a coal tar epoxy coating. The casing pipe diameter shall be six to eight inches greater than the “bell” diameter of the carrier pipe.
B.Wherever steel casing is required on the approved construction drawings, the carrier pipe shall be ductile iron pipe with push-on joints, with the appropriate gaskets.
Approved spacers shall be used to secure the pipe on grade during grouting operations.
C.The materials for casings under state highways shall be in accordance with the Georgia Department of Transportation Standard Specifications for the Construction of Roads and Bridges, latest edition. It shall be the contractor's responsibility to determine the exact requirements of the Georgia Department of Transportation. If there is a conflict between these regulations and the Georgia Department of Transportation Specifications, the latter shall take precedent.
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§ 470-60
Manholes and Precast Concrete Products
470-60.01 Design
A.Manholes shall be installed at the end of each line; at all changes in grade, size, material or alignment; at all intersections; and at distances not greater than 400 feet. In no circumstances will a spacing of greater than 300 feet be allowed when the slope exceeds ten percent. Cleanouts may be used only for service laterals and special conditions and shall not be substituted for manholes. Manholes in cross-country areas shall be elevated so that the top is 18 inches above grade, with bolt down ceiling lids and a vent pipe extending above the 100-year flood elevation. A maximum of 4 pipes shall be allowed to enter into a section of manhole.
B.A drop pipe shall be provided for a sewer entering a manhole at an elevation of more than two feet above the manhole invert. Drop manholes shall be constructed in accordance with the standard detail S-2. The drop pipe shall be of ductile iron materials with mechanical joints. Also, at least one piece of ductile iron pipe shall be used on the incoming line to reach a solid, unexcavated foundation. All outside 90° elbows shall have thrust block poured below the elbow. Outside drop manholes will be noted on the construction plans. Where the difference in elevation between the incoming sanitary sewer and the manhole invert is less than two feet, the invert shall be row back brick, sloped from invert to invert to prevent solids deposition.
470-60.02 Precast Concrete Sections
A.Unless otherwise specified, all manhole components, i.e., base sections, riser sections, conical sections and transition sections (spacers) shall be pre-cast concrete.
B.Pre-cast reinforced concrete manholes shall be eccentric and manufactured in accordance with ASTM C-478 and ASTM C-76, Latest Revision Class II, Wall B, Type II Portland Cement, 4,000 psi. Reinforcing steel shall conform to ASTM A-185. Walls shall be 8 inches minimum or as shown on the Drawings.
C.In flood plains and locations vulnerable to high rates of inflow and infiltration, manholes shall be lined on the inside with a protective liner approved by the Paulding County Water System.
D.Drop manholes, manholes with a force main discharge connection and any other manholes that are susceptible to large amounts of hydrogen sulfide shall be lined on the inside with a protective liner approved by the Paulding County Water System.
E.The manhole table shall have a flow channel made to conform in shape and carrying capacity to that of the sewers.
F.Pre-cast manholes shall have a minimum 28-day cure time before delivery to the site.
G.The minimum inside diameter of manholes shall be 48 inches with an opening of 24 inches at the top of the cone.
H.Transition slabs or cones which convert bases larger than four feet in diameter to four-foot diameter risers shall be designed by the manhole manufacturer to carry the live and dead loads exerted on the slab.
I.Seal joints between precast sections by means of rubber O-ring gaskets or flexible butyl rubber sealant. Butyl rubber sealants shall meet the requirements of AASHTO M-198. Sealant shall be pre-formed type with a minimum nominal diameter of 1-inch. Butyl rubber sealant shall be equal to Kent Seal No. 2 or Concrete Sealants CS202.
470-60.03 Brick and Mortar
A.Brick shall be whole and hard-burned, conforming to ASTM C 32 Grade MS.
Mortar shall be made of one part Portland cement and two parts clean sharp sand. Cement shall be Type 1 and shall conform to ASTM C 150. Sand shall meet ASTM C 144.
470-60.04 Iron Casting
A.For paved areas, cast iron manhole frames and covers shall meet the requirements of ASTM A 48 for Class 30 gray iron per standard details. All castings shall be tough, close grained, smooth and free from blow holes, blisters, shrinkage, strains, cracks, cold shots and other imperfections. No casting will be accepted which weighs less than 95 percent of the design weight. If there is any discrepancy between the standards and specifications and the standard detail, the more stringent applies.
B.For unpaved areas, manhole cover and frame shall be manufactured from ductile iron in accordance with ISO 1083. Covers and frames shall be hinged and incorporate a 90° blocking system to prevent accidental closure. The hinge box shall include a self-cleaning, dual wiper infiltration plug. Covers shall be one man operable using standard tools and shall be capable of withstanding a test load of 120,000 lbs. Frames shall be circular with a 24-inch clear opening and shall include a 360° mechanically attached, C-shaped elastomeric seating gasket for infiltration control and traffic shock. Covers and frames must have at least five years of successful history in a minimum of five thousand installations and be manufactured by an ISO 9000 certified manufacturer. The frame depth shall not exceed 4 inches, and the flange shall incorporate bedding slots, bolt holes and lifting eyes. All components shall be black coated. Frame weight shall be 73 lbs. Cover weight shall be 122 lbs. Total weight shall be 195 lbs.
C.Manhole frames and covers shall be as shown on the Standard Details.
D.All frames and covers shall have machined horizontal bearing surfaces.
E.All manholes shall have standard frames and covers except where specifically shown otherwise on the Drawings.
F.Only solid manhole covers may be used for sanitary sewers.
G.Watertight covers in paved areas shall be bolt-down type and shall be equipped with four 1/2-inch stainless steel bolts and a 1/8-inch red rubber or rubber O-ring gasket. Covers shall be rotatable and interchangeable. Bolt holes shall be bored through so that debris entering the bolt hole will fall into the manhole.
Bolt holes shall have the full 360-degree circle within the cover's radius when bored through the cover.
420-60.05 Steps
Manhole steps shall be polypropylene molded around a steel rod as detailed on the standard detail. See acceptable manufacturers list.
420-60.06 Boots
Provide preformed rubber boots and fasteners equal to those manufactured by Kor-N-Seal or Press Seal Gasket Corporation. See acceptable manufacturers list.
Boots may be mechanically attached to the manhole or cast into the walls of the manhole.
§ 470-70
Miscellaneous Accessories
470-70.01 Wyes and Bends
Wyes and bends shall be equal in quality to the materials of the pipeline being installed.
470-70.02 Concrete and Mortar
A.Concrete shall consist of Portland Cement, a fine aggregate, a coarse aggregate and water. Portland Cement shall conform to Fed. Spec. SS-C-19 lb. Fine aggregate shall be a clean, sharp, well-graded sand conforming to Fed. Spec. SS-S-51. Coarse aggregate shall be uniformly graded broken stone or gravel which will pass a 1½ inch screen and be retained on a ¼ inch screen. Aggregate shall be free of clay, loam silt, or organic matter. Water used for concrete shall be clean and free from vegetable, sewage or organic matter and the total amount used shall not exceed six gallons per sack of cement. Forms may be of wood or metal properly braced to prevent bulging.
Concrete shall be thoroughly mixed and well vibrated into forms and around fittings. Exposed surfaces of concrete shall be protected from premature drying by being kept covered and moist for a period of seven days. After the forms have been removed, the voids in the interior surface, if any, shall be properly filled with cement mortar and the whole surface rubbed uniformly with neat cement.
B.All mortar shall be composed of one part Portland Cement to three parts sand, conforming to these specifications.
C.Concrete shall have a compressive strength of not less than 3000 psi at an age of 28 days, with not less than 5.5 bags of cement per cubic yard and a slump between 3 and 5-inches. For job mixed concrete, submit the concrete mix design for approval by the Engineer. Ready-mixed concrete shall be mixed and transported in accordance with ASTM C 94. Reinforcing steel shall conform to the requirements of ASTM A 615, Grade 60.
470-70.03 Reinforcing Steel
Bars for concrete reinforcement shall be of the sizes, lengths and bent as shown on plans. Bars shall be ASTM Specifications A615, Grade 60. All steel shall be free from rust, scale or any foreign coating.
470-70.04 Brick
All brick shall be best grade, hard-burned, common, giving a ringing sound when struck and acceptable to the Water System. Only bricks presenting a regular and smooth face shall be used. When submerged in water for 24 hours, they shall not absorb more than 10% of their weight in water. Brick shall be culled when delivered on the ground, and all imperfect brick is to be immediately removed from the work. All salmon, soft or arch brick or brick made of alluvial soil will be rejected.
All brick used in the work shall be of uniform size.
470-70.05 Subgrade Stabilizer Stone
Stabilizer for subgrade shall be either approved crushed stone or gravel, uniformly graded from ¼ inch to 1½ inch in size.
470-70.06 Polyethylene Tubing for Ductile Iron Pipe
A.Polyethylene tubing shall be manufactured of virgin polyethylene material conforming to ASTM Standard Specification D-1248-78, Type I, Class A or C, Grade E-1. The polyethylene film shall have a minimum thickness of eight mm.
470-70.07 Casing Spacers
A.Approved casing spacers shall be used to secure the sewer force main, or outfall sewer if directed by the Water System, on grade throughout the length of the casing. The spacers shall be sufficient to secure the pipe on grade during the grouting operation.
Casing end seals shall be pull-over type made from neoprene with T-304 stainless steel bands for securing to the carrier and casing pipe unless dictated otherwise by permitting with GDOT or railroad specifications. When permitting requires different specifications, the more stringent specifications shall apply.
470-70.08 Concrete for Thrust Blocks and Thrust Collars
Concrete for thrust blocks and thrust collars shall be ready-mix and have a minimum compressive strength of 3000 psi at 28 days.
470-70.09 Gaskets for Joint Restraint Inside Casings
Inside of casings, the sewer line joints shall be slip-joint restrained by using the appropriate gaskets. See acceptable manufacturers list.
470-70.10 Grease Interceptors
Grease interceptors will be installed on all commercial sites that prepare or serve food. Grease interceptors are to be located outside of the commercial structures.
470-70.11 Air Release Valves
A.Air release valves may be necessary on force mains to release air pressure.
1.The air release and vacuum break valve shall be of the compact single chamber design with solid cylindrical HDPE control floats housed in a tubular stainless steel body with epoxy powder coated cast iron or steel ends secured by means of stainless steel tie rods.
2.The valve shall have an integral "anti-shock" orifice mechanism which shall operate automatically to limit transient pressure rise or shock induced by closure to two times valve rated working pressure.
3.The intake orifice area shall be equal to the nominal size of the valve.
4.Large orifice sealing shall be affected by the flat face of the control float seating against a nitrile rubber O-ring housed in a dovetail groove circumferentially surrounding the orifice.
5.Discharge of pressurized air shall be controlled by the seating and unseating of a small orifice nozzle on a natural rubber seal affixed into the control float. The nozzle shall have a flat seating land surrounding the orifice so that the damage to the rubber seal is prevented.
6.The valve construction shall be proportioned with regard to material strength characteristics, so that deformation, leaking or damage of any kind does not occur by submission to twice the designed working pressure.
7.The valve design shall incorporate an over pressure safety feature that will fail without an explosive effect, such as is normally the case when highly compressed air is released suddenly. The feature shall consist of replaceable components such as gaskets or seals.
8.Connection to the valve inlet shall be facilitated by a flanged end conforming to ANSI B16.1 Class 125. Flanged ends shall be supplied with the requisite number of stainless steel or mild steel screwed studs inserted for alignment to the specific standard.
9.Provide a 1/4-inch NPT test/bleed cock.
10.An isolation valve between the main and the air valve shall be installed in accordance with the approved construction drawings.
11.Air valve shall be listed in the Sanitary Sewer System Preferred Acceptable Manufacturers List.
§ 470-80
Installation of Sanitary Sewer Mains and
Appurtenances.
470-80.01 Existing Utilities and Obstructions.
A.It is the responsibility of the owner/developer’s contractor to locate the underground utilities and to protect same. Utility lines or services damaged by the owner/developer’s contractor shall be repaired by the owner/developer.
The owner/developer’s contractor shall comply in all respects to the Utilities Protection Center (UPC) (1-800-282-7411) and Georgia law (O.C.G.A. §§25-9-1 through 25-9-13) and all utilities, agencies or departments that own and/or operate utilities in the vicinity of the construction work site.
B.Water, Sewer and Storm Drain Separation
1.A horizontal separation of at least ten feet is required between sanitary sewer lines and existing or proposed water mains (measured edge to edge). Should conditions prevent a separation of ten feet, the lines shall be laid in separate trenches and sanitary sewers shall be ductile iron. Where sewer mains cross existing or proposed water lines, an 24-inch vertical separation is required between the two mains (measured edge to edge).
Ductile iron pipe shall be installed for both mains at points where the two lines cross. The sanitary sewer run of pipe containing the crossing shall be ductile iron from manhole to manhole.
2.Sewers shall have the top of the pipe at least 18 inches below the bottom of the storm drain. On sewer crossings where the vertical separation is less than 12 inches, the sewer pipe shall be mechanical joint DIP coated on the inside with Protecto 401 protective linier or approved equivalent
3.Wherever possible, the elevation of the crown of the sewer shall be at least 24 inches below the invert of the water main. The two pipes shall be installed such that a full length of pipe will be centered over the crossing so that all joints will be separated as much as possible. Ductile iron pipe shall be installed for both mains at points where the two lines cross. The sanitary sewer run of pipe containing the crossing shall be ductile iron from manhole to manhole.
4.No water main shall be permitted to pass through or come in contact with any part of a manhole. There shall be no physical cross-connection between a public or private potable water supply system and a sanitary sewer that would permit the passage of any sewage or polluted water into the potable supply.
5.There shall be a minimum five-foot horizontal separation between parallel gravity and/or force mains.
6.When sewers are laid within public streets, the manholes and lines shall normally be laid along the center of the street at a depth of not less than seven feet below the road surface to the top of the pipe so that service laterals will have six feet of cover at the edge of the right-of-way. In curves and other areas where this is not possible, the lines and manholes are to be installed within the confines of the curb to avoid conflict with the curb and other utilities. Ductile iron pipe shall be used for sewer lines crossing storm sewers and at other locations specified by the Water System.
470-80.02 Construction along Highways, Streets and Roadways.
A.Install pipe lines and appurtenances along highways, streets and roadways in accordance with the applicable regulations of, and permits issued by, the Georgia Department of Transportation and Paulding County DOT with reference to construction operations, safety, traffic control, road maintenance and repair. Any conflict of this section and GDOT or PDOT regulations, GDOT and PDOT regulations govern.
B.Traffic Control
1.The owner/developer shall provide, erect and maintain all necessary barricades; suitable and sufficient lights and other traffic control devices;
provide qualified flagmen where necessary to direct traffic; take all necessary precautions for the protection of the work and the safety of the public. Flagmen shall be certified by a Georgia DOT approved flagman training program.
2.Construction traffic control devices and their installation shall be in accordance with the current Manual On Uniform Traffic Control Devices for Streets and Highways.
3.Placement and removal of construction traffic control devices shall be coordinated with the Georgia Department of Transportation and Paulding County DOT.
4.Placement of construction traffic control devices shall be scheduled ahead of associated construction activities. Construction time in street right-of-way shall be conducted to minimize the length of time traffic is disrupted.
Construction traffic control devices shall be removed immediately following their useful purpose. Traffic control devices used intermittently, such as "Flagmen Ahead", shall be removed and replaced when needed.
5.Existing traffic control devices within the construction work zone shall be protected from damage. Traffic control devices requiring temporary relocation shall be located as near as possible to their original vertical and horizontal locations. Original locations shall be measured from reference points and recorded in a log prior to relocation. Temporary locations shall provide the same visibility to affected traffic as the original location.
Relocated traffic control devices shall be reinstalled in their original locations as soon as practical following construction.
6.Construction traffic control devices shall be maintained in good repair, and shall be clean and visible to affected traffic for daytime and nighttime operation. Traffic control devices affected by the construction work zone shall be inspected daily.
7.Construction warning signs shall be black legend on an orange background. Regulatory signs shall be black legend on a white background. Construction sign panels shall meet the minimum reflective requirements of the Georgia Department of Transportation and Paulding County DOT. Sign panels shall be of durable materials capable of maintaining their color, reflective character and legibility during the period of construction.
8.Channelization devices shall be positioned preceding an obstruction at a taper length as required by the current Manual on Uniform Traffic Control Devices for Streets and Highways, as appropriate for the speed limit at that location. Channelization devices shall be patrolled to ensure that they are maintained in the proper position throughout their period of use.
9.All storage of materials, excavation, backfilling, pavement removal and replacement, clean up and grassing shall be in strict accordance with the applicable State and County regulations. It shall be the owner/developer’s contractor’s responsibility to determine the exact requirements of the authority having jurisdictions over the right- of-way. No highway, road or street shall be closed to traffic or impacted without authorization from the Title 3: Chapter 470 proper authority. The owner/developer’s contractor shall provide suitable lights, signs, barricades, and flagmen to ensure the safety of pedestrian and vehicle traffic and workmen and to protect the work.
10.The owner/developer shall coordinate the closing of any street at least 10 days in advance with the Paulding County Department of Transportation at 770-445-4759.
C.Construction Operations
1.Perform all work along highways, streets and roadways to minimize interference with traffic.
2.Shaping: Reshape damaged slopes, side ditches, and ditch lines immediately after completing backfilling operations. Replace topsoil, sod and any other materials removed from shoulders.
3.Construction operations shall include cleanup and utility exploration.
D.Excavated Materials: Do not place excavated material along highways, streets and roadways in a manner which obstructs traffic. Sweep all scattered excavated material off the pavement in a timely manner.
E.Drainage Structures: Keep all side ditches, culverts, cross drains, and other drainage structures clear of excavated material. Care shall be taken to provide positive drainage to avoid ponding or concentration of runoff.
F.Landscaping Features: Landscaping features shall include, but are not necessarily limited to: fences; property corners; cultivated trees and shrubbery;
manmade improvements; subdivision and other signs within the right-of-way and easement. The owner/developer shall take extreme care in moving landscape features and promptly re-establishing these features.
G.Maintaining Highways, Streets, Roadways and Driveways.
1.Maintain streets, highways, roadways and driveways in suitable condition for movement of traffic until completion and final acceptance of the work.
2.During the time period between pavement removal and completing permanent pavement replacement, maintain highways, streets and roadways by the use of steel running plates. The edges of running plates shall have asphalt placed around their periphery to minimize vehicular impact. The backfill above the pipe shall be compacted, as specified elsewhere up to the existing pavement surface to provide support for the steel running plates.
3.Immediately repair all driveways that are cut or damaged. Maintain them in a suitable condition for use until completion and final acceptance of the work.
Title 3: Chapter 470
470-80.03 Pipe Distribution.
A.Pipe shall be distributed and placed in such a manner that will not interfere with traffic.
B.No distributed pipe shall be placed inside drainage ditches.
C.Distributed pipe shall be placed as far as possible from the roadway pavement, but no closer than five feet from the roadway pavement, as measured edge-to-edge.
470-80.04 Subgrade and Pipe Bedding for Pipe.
A.All D.I.P. pipe shall have a minimum of Class “C” bedding. All PVC pipe shall have a minimum bedding as described below and shown in the standard details. Wherever water or wet soil is encountered, Class “B” bedding shall be provided for D.I.P. If specifically designated on the plans, Class “A” or “B”
bedding may be required.
B.A description of Class “A,” “B,” and “C” bedding is as follows:
1.Class “A” Bedding – Class “A” bedding refers to bedding with concrete cradle, arch or encasement. The owner/developer shall conform to details show in the detailed drawings when Class “A” bedding is required.
2.Class “B” Bedding – The pipe shall be bedded in crushed granite material, conforming to the standard detail approved by the Water System. The bedding shall be placed on a flat trench bottom with a minimum thickness beneath the pipe of one-eighth the outside pipe diameter, but not less than six inches (150 mm) and sliced under the haunches of the pipe with a shovel or other suitable tool to height of one-half the outside pipe diameter, or to the horizontal centerline. The initial backfill shall be hand placed to a level of 12 inches (300 mm) over the top of the pipe and shall consist of finely divided materials free from debris, organic material and large rocks or stones.
3.Class “C” Bedding – The pipe shall be bedded in subgrade stabilizer stone placed on a flat trench bottom. The bedding material shall have a minimum thickness beneath the pipe of six inches (150 mm) or one-eighth of the outside diameter of the pipe, whichever is greater, and sliced under the haunches of the pipe with a shovel or other suitable tool to a height of one-sixth the outside diameter of the pipe. The initial backfill shall be hand placed to a level of 12 inches (300 mm) over the top of the pipe and shall consist of finely divided materials free from debris, organic material and large rocks or stones. Bedding materials shall be as described in the standard detail.
4.Special Bedding for PVC Pipe – The pipe shall be bedded in crushed granite material, conforming to the section of these Regulations on “Subgrade Stabilizer Stone,” or other materials approved by the Water System. The bedding shall be placed on a flat trench bottom with a minimum thickness beneath the pipe of one-fourth the outside pipe diameter, but not less than six inches (150 mm) and sliced under the haunches of the pipe with a shovel or other suitable tool to height of two-thirds the outside pipe diameter. The initial backfill shall be hand placed to a level of 12 inches (300 mm) over the top of the pipe and shall consist of finely divided materials free from debris, organic material and large rocks or stones.
470-80.05 Location and Grade.
The approved construction drawings show the alignment and grade of the sewer and the position of manholes and other appurtenances. The slope shown on the profile and/or called for in the approved construction drawings is the slope of the invert of the pipe.
470-80.06 Laying and Jointing Pipe and Accessories.
A.Lay all pipe and fittings to accurately conform to the lines and grades established by the approved construction drawings.
B.Pipe Installation
1.Proper implements, tools and facilities shall be provided for the safe installation of the sanitary sewer infrastructure. Under no circumstances shall sewer materials be dropped or dumped into the trench.
2.All pipe, fittings and appurtenances shall be examined carefully for damage and other defects immediately before installation. Defective materials shall be marked and held for inspection by the Water System Engineering Technician, who may reject the materials. The owner/developer will not utilize the rejected materials.
3.All lumps, blisters and excess coating shall be removed from the socket and plain ends of each pipe, and the outside of the plain end and the inside of the bell shall be wiped clean and dry and free from dirt, sand, grit or any foreign materials before the pipe is laid. No pipe which contains dirt shall be laid.
4.Foreign material shall be prevented from entering the pipe while it is being placed in the trench. No debris, tools, clothing or other materials shall be placed in the pipe at any time.
5.As each length of pipe is placed in the trench, the joint shall be assembled and the pipe brought to correct line and grade. The pipe shall be secured in place with approved backfill material.
6.It is common practice to lay pipe with the bells facing the direction in which work is progressing, however, it is not mandatory.
7.Applying pressure to the top of the pipe, such as with a backhoe bucket, to lower the pipe to the proper elevation or grade shall not be permitted.
8.Polyethylene Encasement: Installation shall be in accordance with AWWA C105 and the manufacturer's instructions. All ends shall be securely closed with tape and all damaged areas shall be completely repaired to the satisfaction of the Water System Engineering Technician.
C.Alignment and Gradient
1.Lay pipe straight in alignment and gradient or follow true curves, as shown on the approved construction drawings, as nearly as practicable. Do not deflect any joint more than the maximum deflection recommended by the manufacturer.
2.Use current regulations, appropriate tools and equipment on the job to lay out angles and ensure that deflection allowances are not exceeded.
3.The owner/developer shall check the invert elevation at each manhole and the pipe invert elevation to ensure accuracy and compliance with the approved construction drawings.
4.The owner/developer shall check the horizontal alignment of the sewer to ensure invert elevations.
D.Progression of Work. Backfill and compact the trench as soon as possible after laying and jointing is completed. Cover the exposed end of the installed pipe each day at the close of work and at all other times when work is not in progress. If necessary to backfill over the end of an uncompleted pipe or accessory, close the end with a suitable plug, either push-on, mechanical joint, restrained joint or as approved by the Water System Engineering Technician.
E.Joint Assembly
1.Push-on, mechanical, flange and restrained type joints shall be assembled in accordance with the manufacturer's recommendations.
2.The owner/developer’s contractor shall inspect each pipe joint within 1,000 feet on either side of main line valves to insure 100 percent seating of the pipe spigot, except as noted otherwise.
3.Each restrained joint shall be inspected by the owner/developer’s contractor to ensure that it has been “homed” 100 percent.
F.Cutting pipe
1.Cut ductile iron pipe using an abrasive wheel saw.
2.Cut PVC pipe using a suitable saw.
3.Remove all burrs and smooth the end before jointing.
4.The owner/developer shall cut the pipe and bevel the end, as necessary, to provide the correct length of pipe necessary for installing the fittings, valves, accessories and closure pieces in the correct location. Only push-on or mechanical joint pipe shall be cut.
G.Building Connections. Install wyes or tees in locations shown on the approved construction drawings for future connection of service lines. Plug the branch of the wye or tee. Record the location of fittings installed on the as-builts and submitted to Community Development.
470-80.07 Trench and Manhole Excavation.
A.Sanitary sewer lines shall normally be installed by open-cut trench excavation.
Pipe trenches shall be excavated straight and true to grade and line and in the location shown on the approved construction plans. Trenches shall be dug so that the pipe can be laid to the alignment and depth required, and the trench shall be of such width and shall be braced and drained so that the workmen may work therein safely and efficiently. Chocking under the pipe will not be permitted. Excavation must be made under the bell of each pipe so that the entire length of the pipe will lie uniformly on the bottom of the trench and the pipe weight shall not rest on the bells. Trenches shall be free of water during the work.
1.Trenches shall have a minimum width of 12 inches plus the diameter of the outside of the bell of the sewer main and the maximum trench width at the centerline of the pipe shall not be more than the nominal diameter of the pipe plus two feet. See standard detail. In unpaved areas, the trenches may have a greater width that this, beginning at one foot above the top of the pipe and extending to the ground surface, if such width is necessary or desirable. However, in paved areas, the width of the trench from top to bottom shall not exceed the diameter of the pipe plus two feet.
2.In cases where water mains cross above sanitary sewers, there shall be a minimum clearance of 18 inches vertical separation between the water and sewer mains. In cases where a sanitary sewer crosses above a water main, there shall be a minimum clearance of 18 inches vertical separation between the mains, plus the sanitary sewer main shall be encased in concrete. Both mains shall be Ductile Iron Pipe. At crossings, one full length of sewer pipe must be located so that both joints are as far from the water main as possible. In cases where sanitary sewer mains parallel water mains, there shall be a minimum of ten (10) feet horizontal separation maintained between the mains. These distances are measured edge to edge.
3.No excavation shall be made under highways, streets, alleys or private property until satisfactory arrangements have been made with the GDOT, City, Paulding County DOT or owners of the property to be crossed. All excavated material shall be placed so as to not interfere with public travel on the streets and highways along which the lines are laid.
4.When possible, all crossings of paved highways or driveways by pipe line shall be made by boring or jacking the pipe under the pavement and shall be done in such manner as not to damage the pavement or foundation, unless the casing or pipe is in solid rock, in which case the crossing shall be made by the open cut method or by tunneling.
5.Wherever streets, roads or driveways are cut, they shall be immediately backfilled and compacted after the pipe is laid and shall be maintained in first-class condition as passable at all times until repaved. See standard Utility Cut detail.
6.Backfilling, compaction, dressing and clean-up shall be kept as close to the line laying crew as is practical, and negligence in this feature of the work will not be tolerated.
7.In excavation and backfilling and laying pipe, care must be taken not to remove or injure any water, sewer, gas or other pipes, conduits or other structures without permission from the Water System. When an obstruction is encountered, the owner/developer shall notify his designer Title 3: Chapter 470 who will coordinate with the owner of the obstruction and make necessary changes in grade and/or alignment to avoid such obstruction. Any house connection, drains or other structures damaged by the owner/developer shall be repaired or replaced immediately. Owner/developer is responsible for ensuring no damage occurs to other utilities.
8.All excavation materials shall be placed on one side of the trench, unless permission is given by the Water System to place it on both sides.
Excavation materials shall be so placed as not to endanger the work and so that free access may be had at all times to all parts of the trench and to all fire hydrants or water valve boxes, etc. All shade trees, shrubs, etc., shall be protected.
9.The excavation for manholes shall extend to a firm, acceptable foundation as shown in the standard details and leave not less than 24 inches in the clear between their exterior surface and the embankment or retaining structure that may be used to protect it.
10.The owner/developer shall furnish, install and maintain such including but not limited to sheathing and bracing as may be required to support the sides of the excavation and to prevent any movement that might injure the pipe, or cause sloughing of the street or trench, or otherwise injure or delay the work or interfere with adjoining structures.
11.Construction occurring around active sanitary sewerage systems shall be done in such a way so as to prevent the spillage of sewage.
B.All materials shall be considered as rock which cannot be excavated except by drilling, blasting or wedging. It shall consist of undecomposed stone in solid layers or of boulders of not less than one-half cubic yard. Wherever rock is encountered in the excavation, it shall be removed by suitable means. If blasting is used for removal of rock, the owner/developer shall take all proper safety precautions. All blasting operations and all handling, storage and use of blasting materials shall be in strict accordance with federal, state and local ordinances and regulations and shall be approved by the Paulding County fire marshal. Blasts shall be restricted to the extent that no appreciable shock will be transmitted to existing structures, pipe lines, sewers, cables or other public or private facilities. Owner/developer is fully responsible for filing for and acquiring any blasting permits that may be required by those agencies having jurisdiction. Before blasting, the owner/developer shall cover the excavation with heavy timbers and mats in such a manner as to prevent damage to persons or the adjacent property. Rock excavation near existing pipelines or other structures shall be conducted with the utmost care to avoid damage. The owner/developer shall be wholly responsible for any and all personal injury or property damage resulting from blasting and any injury or damage to structures or property shall be promptly repaired by the owner/developer to the satisfaction of the Water System and property owner.
C.Rocks in trenches shall be excavated over the horizontal limits of excavation and to depths as shown in Table 470.4.
Title 3: Chapter 470
Table 470.4
| Size of Pipeline (Inches) | Depth (Inches) |
|---|---|
| 4-6 | 6 |
| 8-18 | 8 |
| 18-30 | 10 |
| 30 inches and larger | 12 |
where it is to be laid in the trench. All such material that is defective in manufacture or has been damaged in transit or after delivery shall be removed from the job site.
C.All pipe and appurtenances shall be of the dimensions and laid to the line and grade as shown on the approved construction plans. Wyes and/or service connections and stubs from manholes shall be placed where shown on the approved construction plans. All such connections shall be blanked off with suitable stopper and made watertight with jute and cement mortar.
D.The preferred order of construction is to connect to existing sanitary sewers after all other construction is complete and conditionally accepted by the Water System. Connections to existing sanitary sewers can be done at the beginning of construction; however, the new main shall be plugged where it enters either the existing manhole or the new doghouse manhole as shown in the standard detail over an existing sanitary sewer, and the plug shall remain in place until the project is conditionally accepted.
E.Sanitary sewer pipes shall be joined by “push-on” joints using elastomeric gaskets to affect the pressure seal. The ends of pipe to be joined and the gaskets shall be cleaned immediately before assembly, and the assembly shall be made as recommended by the pipe manufacturer. Lubricant used must be non-toxic and supplied or approved for use by the manufacturer. Sanitary sewer pipes shall be laid in the uphill direction with the bells pointing upgrade.
Any variation from this procedure shall require approval from the Water System.
F.Bell holes shall be provided of sufficient size to allow ample room for making the pipe joints without putting any load on the bell of the pipe. The bottom of the trench between bell holes shall be carefully graded so that the pipe barrel will rest on a solid foundation for its entire length as shown on the approved construction plans. Pipe shall be laid with joints close and even, butting all around, so that it will form a close concentric joint with adjoining pipe with no sagging at the hub and so that a true surface is given to the invert throughout the entire length of the sewers. After the pipe is laid, backfilling shall be completed as directed in these standards and specifications.
G.The owner/developer shall be required to provide and operate any equipment necessary to keep the trenches free from water while pipe is being laid and the joints made. The installed pipe shall not be used for draining water from the ditch.
H.Pipe grades shall be obtained by use of a laser and double-checked with a surveying level and rod.
I.Completed sewers shall be tested between manholes with lanterns or reflected light and shall show the full circle of the pipe from manhole to manhole without obstruction.
J.Sewers shall be laid tight and the rate of infiltration in any section of line between adjacent manholes shall not exceed 100 gallons per day per inch diameter of pipe per mile of line when the trenches are saturated with water.
K.All openings along the line of sewers shall be securely closed at night, during suspension construction, and at the end of each construction period, with a water-tight stopper.
L.No length of pipe shall be laid until one preceding it shall have sufficient quantity of fine earth tamped around it to hold it firmly in place.
Title 3: Chapter 470
470-80.09 Making of Joints.
When joining gravity sewer pipe, both the spigot end and the bell end of the pipe shall be perfectly clean and free from dirt, oil, grease or other foreign matter. The spigot end shall be lightly coated with the lubricant recommended and furnished by the manufacturer, and the pipe then shall be securely and firmly seated in the bell end of the adjoining pipe. In making the joint, the spigot end of the pipe, after being cleaned and coated with lubricant, shall not be allowed to touch the sides or bottom of the trench before being inserted in the bell end of the adjoining pipe. In addition to the above, joints shall be made in strict accordance with the specifications and recommendations of the manufacturer.
470-80.10 Dewatering Trenches.
The owner/developer’s contractor shall do all necessary pumping or bailing, build all drains and do all other work necessary to keep the trenches clear of water during the progress of the work. No structure shall be built or pipe shall be laid in water, and water shall not be allowed to flow over or rise upon any concrete, masonry or pipe until the same has been inspected and the concrete or joint material has thoroughly set. All water pumped, bailed or otherwise removed from the trench or other excavation shall be conveyed in a proper manner to a suitable place of discharge consistent with the approved construction plans where it will not cause injury to the public health or to public or private property or to work completed or in progress, or to the surface of the streets or cause any interference with the use of same by the public.
470-80.11 Backfilling.
A.After the pipe has been laid, backfilling shall be done in two distinct operations.
In general, all backfill beneath, around and to a depth of 12 inches above the top of the pipe shall be placed by hand in four-inch layers for the full width of the trench and thoroughly compacted by hand with vibratory equipment. The remainder of the backfill shall be placed in six-inch layers and compacted to the top of the trench, either by pneumatic had tamps, hydro-tamps, or other approved methods. Care shall be taken so that the pipe is not laterally displaced during backfilling operations. The backfill lifts shall be placed by an approved method in accordance with that hereinafter specified.
B.Backfill materials should be clean and free of rocks larger than two inches at its largest dimension. Backfill materials shall be the excavated materials without bricks, stone, foreign matter (which will include organics, cinders, stumps, limbs, frozen earth and manmade material) or corrosive materials, where not otherwise specified or indicated on the approved construction plans.
C.Backfill under permanent concrete or bituminous pavement and as elsewhere specified or indicated on the plans shall be approved bank-run sand or gravel or crushed stone free from large stones and containing not more than ten percent (10%) by weight of loam or clay. This backfill shall be compacted to 100 percent as determined by the Modified Proctor test for the top two feet of trench and 95 percent by the Modified Proctor test from pipe bedding to two feet below trench top. Mechanical vibrating equipment shall be used to achieve the required compaction. Pavement shall be replaced immediately after the backfilling operation is completed.
D.Backfill under gravel or crushed stone surfaced roadways shall be as described in subparagraph 2 above with the approved suitable excavated material placed in six-inch layers thoroughly compacted for the full depth and width of the trench, conforming to the compaction, density compaction method and materials as specified in the immediately preceding paragraph.
E.Backfill in unpaved areas shall be compacted with mechanical vibrating equipment to 90 percent as determined by the Modified Proctor test. Backfill material from pipe bedding to ground surface shall be excavated as described in subparagraph 2 above.
F.The owner/developer shall fully restore and replace all pavement, sidewalks, landscaping or surface structures, removed or disturbed as part of the work to a condition equal to or better than before the work began.
G.Where sheeting is used in connection with the installation of sanitary sewer, it is in no case to be withdrawn before the trench is sufficiently filled to prevent damage to banks, road surfaces, adjacent pipes, adjacent structures or adjacent property, public or private.
470-80.12 Stream Crossings.
A.The preferred method of crossing a river, stream, creek impoundment or wet weather ditch is with a minimum of two feet of cover between the lowest point in the stream and the top of outside diameter of the pipe. Ductile iron pipe is required for all stream crossings and shall extend a minimum of 10 feet beyond the top of the bank on each side. Concrete collars or encasement must be provided at all joints for ductile iron pipe with less than three feet of cover.
B.The stream bed and banks at the crossing site shall be protected from erosion with the use of rip-rap, as defined and sized in the Manual for Erosion and Sediment Control in Georgia, Appendix C (Construction Materials), most current edition.
C.Aerial crossings will require detailed design plans in the approved construction drawings and will be allowed only when there is no reasonable alternative.
D.Specific erosion control measures are to be shown in the approved construction drawings and shall be installed prior to installing pipe across any stream. All work should be performed when stream flows are at their lowest, and all work should be performed as quickly and safely as possible. As soon as conditions permit, the stream bed shall be cleared of all falsework, debris, and other obstructions placed therein or caused by the construction operations.
E.Erosion control measures can include, but are not limited to, the following items:
1.Silt fencing, types A, B and/or C;
2.Erosion control check dams;
3.Channel diversion through temporary storm drain pipe; and
4.Rock filter dams. The construction and installation of these various structures are detailed in the Manual for Erosion and Sediment Control in Georgia or the GDOT Construction Standards and Details sections on erosion control.
470-80.13 Casing for Sanitary Sewers.
A.Where pipe is required to be installed under railroads, highways, streets or other facilities by jacking or boring methods, construction shall be done in a manner that will not interfere with the operation of the utility, and shall not weaken the roadbed or structure.
B.Casing pipe shall be installed at the locations shown on the approved construction plans. Unless directed otherwise, the installation procedure shall be the dry bore method. The hole is to be mechanically bored and cased through the soil by a cutting head on a continuous auger mounted inside the casing pipe. The installation of the casing and boring of the hole shall be done simultaneously by jacking. The diameter of the bore shall conform to the outside diameter and circumference of the casing pipe as closely as practical.
Any voids that develop during the installation operation shall be pressure grouted. Each segment of the casing pipe shall be welded (full circumference butt weld) to the adjoining segment. The completed casing shall have no sags or crowns that cause the grade for any segment to be less than the minimum slope for the size pipe being installed.
C.Excavation material will be removed and placed at the top of the working pit.
Backfill material and methods of backfilling and tamping shall be as previously outlined in this Division. Carrier pipe shall be DIP and shall be inserted within the casing by use of approved casing spacers. Inside of casings, the sewer main joints shall be slip joint restrained by using gaskets. See acceptable manufacturers list.
D.The annular space between the carrier pipe and the casing shall be pressure grouted after the carrier pipe is sufficiently secured on grade to prevent floating during grouting. The carrier pipe should be filled with water prior to grouting to aid in the prevention of floating. At each end of the casing pipe, the void between the carrier pipe and casing shall be sealed with brick and mortar.
470-80.14 Sewer Laterals.
A.A sewer lateral shall be provided for every existing or proposed lot or building.
All sewer laterals must be shown on the construction drawings. All sewer laterals shall be minimum of six inches in diameter. A common sewer lateral shall not be allowed for two or more buildings. The sewer lateral shall extend to the property line of the lot being served and normally be within 10 feet of the lower corner of the lot. The owner/developer shall install a cleanout at the right-of-way and extend the PVC cleanout to a height of three feet above the finished grade. All sewer laterals shall have six feet of cover at the right-of-way. Where six feet of cover cannot be achieved, services shall be ductile iron.
B.Six-inch services shall be laid at a minimum grade of one percent. Sewer laterals tied directly to manholes shall enter the manholes through cored holes and shall be provided with a pre-molded rubber boot. Laterals shall enter the manhole no higher than six inches above the table and shall be provided with a concrete flume to slope the flow into the manhole invert.
C.The developer shall be responsible for serving all lots developed. On any lot where the sewer lateral cannot be found, the developer shall be responsible for payment of the cost of installation of another sewer lateral. Also, unless noted on the final plat, the sewer shall be low enough to serve the first floor elevation at the building line. The builder shall be responsible for locating the sewer lateral prior to the pouring of the foundation, driveway or other appurtenances. The Water System will not be responsible for any house built too low to be served nor for any sewer lateral covered by construction.
D.No plumber or owner/developer will be allowed to connect to the sewerage system except to the end of the service provided for this connection, when building permit has been issued. After the service is run from the end of the lateral provided by the sewer line owner/developer to the house plumbing, the cleanout at the right-of-way may be cut down to a level six inches below the finished grade. The cleanout shall be provided with a cast iron ferrule with a brass screw plug to enable the cleanout to be located with a metal detector.
Plastic plugs are not allowed.
470-80.15 Setting Fittings on Force Mains.
A.Fittings shall be placed where shown on the plans. Fittings shall be properly braced to ensure that they will not be blown off or broken loose under the greatest possible force of the sewage flow. All fittings shall be mechanical joint with retainer glands unless specified otherwise. In situations where there is insufficient undisturbed earth to act as a bearing surface as shown on the approved construction plans or where otherwise directed by the water system engineering technician in consultation with the engineering manager, fittings shall be restrained by the use of threaded rods.
B.Prior to blocking any joint or fitting with concrete, that joint or fitting shall be wrapped with polyethylene film in such a manner that the concrete will not stick directly to the pipe and that the load bearing capacity of the blocking will not be affected.
470-80.16 Bracing, Sheeting and/or Shoring.
Whenever the condition of the ground is such that it is necessary to protect the work, the street, the roadway or the workmen, the sides of the trench shall be supported with suitable bracing, sheeting and/or shoring in full compliance with all state and federal regulations.
470-80.17 Removing and Replacing Pavement.
A.All paved roads will be bored and cased. A bore must be attempted before consideration will be given to cutting the street.
B.Existing roadways shall not be open cut unless a permit is granted by the Georgia D.O.T. and/or the Paulding County Department of Transportation.
Submittal of an authorization letter from the State D.O.T. or the County D.O.T.
is required.
C.One lane of traffic shall be maintained open at all times. Construction work shall be limited to time between 9 a.m. and 4 p.m.
D.The owner/developer shall furnish traffic control devices and certified personnel to direct traffic per permit.
E.The above requirements may be altered with the written approval of the PDOT in extenuating circumstances.
F.Remove existing pavement as necessary for installing the pipeline and appurtenances.
1.The owner/developer shall replace with like materials at his expense all pavements, walks, and driveways removed or damaged in connection with the work. Pavement repairs shall be smooth and unnoticeable and of the same elevation as the existing paving. In the removal of pavement, the owner/developer shall salvage all sound and undamaged materials and store them at a convenient location for reuse in pavement replacements.
Any additional new rock concrete, asphalt or other replacement materials shall in all cases conform to the PDOT’s specifications.
2.Before removing any pavement, mark the pavement neatly paralleling pipelines and existing street lines. Space the marks the width of the trench in neat lines.
3.Saw cut asphalt pavement along the marks using a rotary saw or other suitable tool. Break concrete pavement along the marks by scoring with a rotary saw and breaking below the score by the use of jackhammers or other suitable tools.
4.Do not pull pavement with machines until completely broken and separated from pavement to remain.
5.Do not disturb or damage the adjacent pavement. If the adjacent pavement is disturbed or damaged, remove and replace the damaged pavement.
6.Remove and replace sidewalks disturbed by construction for their full width and to the nearest undisturbed joint.
7.Remove and replace or tunnel under any curb disturbed by construction to the nearest undisturbed joint.
G.Upon completion of backfilling and consolidation of the backfill, arrange to have the compaction tested by an independent testing laboratory approved by PDOT. After compaction testing has been satisfactorily completed, replace all pavements, sidewalks and curbs removed. Gravel roads and drives shall meet the requirements for graded aggregate sub-base.
1.Pavement restoration shall meet the requirements of GDOT or PDOT.
2.On 3rd party property, restoration of offsite pavement must be to the same or better condition and with PDOT approval.
3.Complete pavement restoration as soon as possible after backfilling.
4.Prior to replacing pavement, make a final cut in the pavement 12-inches back from the edge of the previous cut line. Make the cut using a rotary saw. Remove pavement and base material to a depth of 10-inches below finished grade. Construct an eight-inch thick concrete (3000 psi) bridge the full width of the pavement cut (i.e... trench width plus 24-inches). Apply tack coat and two-inches of Type F asphalt when concrete has cured. See utility Title 3: Chapter 470 cut detail.
5.Replace all street roadway pavement, driveways, sidewalks, and curbs with the same material and to the same dimensions as existing.
6.Should any pavement restoration or repairs fail or settle during the life of the Contract, including the bonded period, promptly restore or repair defects.
7.Concrete pavement removal and replacement shall conform to the applicable sections of the Georgia Department of Transportation Standard Specifications for the
H.Construction of Roads and Bridges, latest edition or PDOT standards as applicable.
470-80.18 Railroad Crossings.
Railroad crossings shall be made in accordance with all requirements of the affected railroad. It will be the owner/developer’s responsibility to obtain all requirements from the railroads and furnish all labor and materials required to fulfill such requirements. The owner/developer shall furnish and install the casing under the tracks with whatever material and with whatever methods and under whatever regulations are required by the railroads.
470-80.19 Connection to Paulding County’s Existing Sanitary Sewer System.
A.Only a utility contractor preapproved by the Water System shall make all required connections to the County’s sewer system. The Water System’s Engineering Technicians will supervise the connection and all associated work.
The owner/ developer shall give the Water System personnel a minimum of 48 hours’ notice prior to any sanitary sewer system connection work.
B.The owner/developer will provide proper traffic control devices and certified personnel to direct traffic if required to complete sanitary sewer connection work.
C.All connections to existing manholes shall be properly cored with a coring machine. “Knocking-out” of a hole in the manhole for a connection is not permitted.
D.The timing of the owner/developer’s connection to the County’s sanitary sewer system shall be pre-arranged with the Water System.
470-80.20 Street Cuts.
A.Assuming that a road bore has been attempted and failed, and that the owner/developer has received a permit to open cut a road, pavement replacement shall adhere to the following guidelines:
1.Removing and replacing pavement shall consist of removing the type of pavement and base encountered, and replacing same to its original shape, appearance and riding quality, in accordance with the detailed plans.
Where possible, all pipe under existing paved driveways will be either free bored or installed in casing. Free bores under driveways will be made with ductile iron pipe. Casing will be required where the installation is under any roadway. Carrier pipe shall be ductile iron pipe.
2.Concrete pavement shall be replaced with pavement of a thickness equal to that removed, or six inches for driveways and eight inches for roads, whichever is thicker. The concrete shall meet the specifications of GDOT for concrete paving.
3.Where bitumastic paving is replaced, a base course of 3000 psi. concrete shall be placed over the ditch line. The concrete shall be six inches thick for driveways and parking lots and eight inches thick for public roads. The top of this base course shall be left with a rough float finish 1-1/2" below the surface of the existing paving. After the concrete has attained its strength, a tack coat of AC-15 or equal shall be applied at the rate of 0.25 gallons per square yard, and a plant mix surface course applied over this, and finished off level with existing pavement.
4.Unless otherwise directed in writing, all pavement shall be removed to a width of the trench plus 12 inches on each side as shown on the utility cut standard detail. Under normal circumstances, the maximum allowable trench width shall be the nominal diameter of the pipe plus 24 inches.
470-80.21 Clean-Up.
A.All trenches shall be backfilled and tamped before the end of each day’s work.
B.Prior to requesting the final inspection, the owner/developer shall do the following:
1.Repair or replace any work damaged by the sewer line construction.
2.Regrade and smooth all shoulder areas disturbed by the sewer line construction.
3.All easement areas shall be cleared of trees, stumps and other debris and left in a condition such that the easement can be maintained by bush-hog equipment.
4.All shoulders, ditches, culverts and other areas impacted by the sanitary sewer construction shall be at the proper grades and smooth in appearance.
5.All manhole covers shall be brought to grade.
6.A uniform stand of grass or mulch for erosion protection, as defined in the Manual for Erosion and Sediment Control in Georgia is required over all construction easements and sanitary sewer easements prior to the Water System’s acceptance of the sanitary sewer.
470-80.22 Manhole and Precast Concrete Product Construction.
A.Precast Manholes
1.Precast manholes shall be constructed of Portland Cement concrete with a compressive strength of not less than 4000 psi. at an age of 28 days.
The minimum inside diameter of the manhole shall be as required by the manhole Standard Details. The wall thickness shall not be less than five inches. Manholes shall be placed on a stable subgrade. Joints in the wall shall be tongue and groove type. Sections shall be joined using O-ring rubber gaskets, flexible plastic gaskets conforming to the applicable provisions of ASTM Standard Specification, Serial Designation C443, or an approved bitumastic joint material.
2.Precast concrete manholes shall consist of precast reinforced concrete sections with eccentric (or flat slab for shallow manholes) top section and a base section conforming with the typical manhole details as shown on the Standard Detail. Flat top manholes will be approved only if a need for such can be demonstrated by the owner/developer.
3.Each section of the precast manhole shall have not more than two holes for the purpose of handling and laying. These holes shall be sealed with cement mortar using one part Portland Cement to two parts clean sand, meeting ASTM Standard Specifications, Serial Designation C144.
4.Precast bases shall be fabricated at the factory with invert penetrations at the required locations and heights. Knocking out of holes in the precast bases in the field will not be permitted; however, holes can be cored in the field with a coring machine. Material on the job site that is found defective shall be removed immediately after being notified that such materials are unacceptable. Precast manhole shall conform to ASTM C478.
5.Pipe Connections: Seal the connection between the pipe and the manhole as follows:
(a)Pipe 36-Inch Diameter and Less: Connect pipe to manhole utilizing rubber boots.
(b)If rubber boots are damaged, replace Type I boots with a new boot and repair Type II boots by constructing a manhole collar.
(c)If preformed openings must be enlarged or altered, or if new openings must be made in the field, minimize the amount of material removed to provide closely matched surfaces or grouting.
(d)Pre-molded rubber boots with stainless steel bands shall be used for connecting sewer pipe to manholes. These may either be the lock-in “Kor-N-Seal” type, or approved equal. In all cases, the boot shall be sized to suit the outside diameter of the type pipe being used.
6.The invert of manholes shall be constructed of concrete or brick in accordance with the Standard Details S-3 and shall have a cross section of the exact shape of the invert of the sewer that it connects, changes in size and grade being made gradually and evenly. Changes in the direction of the sewer and entering branch or branches shall have a true curve of as large a radius as the size of the manhole will permit. Inverts shall have a “smooth trowel” finish. The manhole bench shall be sloped 30 degrees from the manhole wall toward the invert. Manholes shall be provided with steps built into the wall as shown on the detailed drawing S-10.
B.Manhole Steps
1.Manhole steps shall be of #4 steel reinforcing bars covered with Polypropylene Plastic or rubber and shall be supplied with depth rings as shown in standard detail S-10. The manhole steps shall conform to the Title 3: Chapter 470 applicable provisions of ASTM Specification C478. See list of preferred acceptable manufacturers. The steps shall be factory built into the precast sections.
C.Manhole Cover and Frame. Manhole covers shall be cast iron with a coat of asphaltic paint applied at the foundry. The frame and cover shall be as shown on the detail drawings. All covers shall have “Sewer” printed on them.
Manhole frame and covers shall be as manufactured by Neenah R-1765 (365 lbs.) in paved roads, parking lots and driveways, and Neenah R-1779 (300 lbs.)
for non-traffic areas, or approved equal. Manhole frames shall be cast in the cone if located in non-traffic areas.
D.Waterproof Manhole Frame and Cover. Waterproof manhole covers shall be cast iron with a coat of asphaltic paint applied at the foundry as shown on the drawings with a “bolted-down” lid. All covers shall have “Sewer” printed on them. Manhole frame and covers shall be as manufactured by Neenah Foundry Company R-1915-F2 (435 lbs.) or approved equal. Manhole frames shall be cast in the cone if located in a non-traffic area.
E.Manhole Foundation. The manhole base shall be set on a compacted mat of No. 57 crushed stone graded level at the thickness shown on the standard detail drawings S-1, S-2 and S-3. In wet areas, the crushed stone mat shall be thickened as needed to provide a non-yielding foundation.
F.Brick. Brickwork required to complete the precast concrete manhole shall be constructed to meet ASTM Specifications, Serial Designation C144, thoroughly mixed to a workable plastic mixture. Brickwork shall be constructed in a neat and workmanlike manner. Bed the bottom and sides of every brick in mortar.
Apply a smooth coat of mortar, 3/4-inch thick, on the inside and outside.
Cement mortar shall be used to grout interior exposed brick joints and faces.
No more than three courses of brick with nine-inch maximum total depth of bricks may be used to adjust manhole covers.
G.Top Elevations. Build manholes outside of paved areas to 18-inches above finished grade unless otherwise shown on the approved construction drawings.
Build manholes in paved areas to existing grades.
H.Drop Connections. Manholes requiring drop connections shall be shown on the approved construction drawings and shall be shown as indicated on the standard details. When a drop manhole is used the pipe material from the upstream manhole to the drop manhole shall be ductile iron.
470-80.23 Jack and Boring.
A.Where the approved construction drawings indicate a pipeline is to be installed by jack and boring with casing, the owner/developer shall construct the crossing by the jack and boring method.
1.Shaft
(a)Conduct boring and jacking operations from a shaft excavated at one end of the section to be bored. Where conditions and accessibility are suitable, place the shaft on the downstream end of the bore.
(b)The shaft shall be rectangular and excavated to a width and length required for ample working space. If necessary, sheet and shore shaft properly on all sides. Shaft sheeting shall be timber or steel piling of ample strength to safely withstand all structural loadings of whatever nature due to site and soil conditions. Keep preparations dry during all operations. Perform pumping operations as necessary.
(c)The bottom of the shaft shall be firm and unyielding to form an adequate foundation upon which to work. In the event the shaft bottom is not stable, excavate to such additional depth as required and place a gravel sub-base or a concrete sub-base if directed by the Engineer due to soil conditions.
2.Jacking Rails and Frame
(a)Set jacking rails to proper line and grade within the shaft. Secure rails in place to prevent settlement or movement during operations. The jacking rails shall cradle and hold the casing pipe on true line and grade during the progress of installing the casing.
(b)Place backing between the heels of jacking rails and the rear of the shaft. The backing shall be adequate to withstand all jacking forces and loads.
(c)The jacking frame shall be of adequate design for the magnitude of the job. Apply thrust to the end of the pipe in such a manner to impart a uniformly balanced load to the pipe barrel without damaging the joint ends of the pipe.
3.Boring and jacking of casing pipes shall be accomplished by the dry auger boring method without jetting, sluicing or wet boring.
4.Auger the hole and jack the casing through the soil simultaneously.
5.Bored installations shall have a bored-hole diameter essentially the same as the outside diameter of the casing pipe to be installed.
6.Execute boring ahead of the casing pipe with extreme care, commensurate with the rate of casing pipe penetration. Boring may proceed slightly in advance of the penetrating pipe and shall be made in such a manner to prevent any voids in the earth around the outside perimeter of the pipe.
Make all investigations and determine if the soil conditions are such as to require the use of a shield.
7.As the casing is installed, check the horizontal and vertical alignment frequently. Make corrections prior to continuing operation. For casing pipe installations over 100 feet in length, the auger shall be removed and the alignment and grade checked at minimum intervals of 60 feet.
8.Any casing pipe damaged in jacking operations shall be repaired, if approved by the Water System Engineering Manager or his designee, or removed and replaced at owner/developer's own expense.
9.Lengths of casing pipe shall be as long as practical. Joints between casing pipe sections shall be butt joints with complete joint penetration, single groove welds, for the entire joint circumference, in accordance with AWS Title 3: Chapter 470 recommended procedures. Prior to welding the joints, the owner/developer shall ensure that both ends of the casing sections being welded are square.
10.The owner/developer shall prepare a contingency plan which will allow the use of a casing lubricant, such as bentonite, in the event excessive frictional forces jeopardize the successful completion of the casing installation.
11.Once the jacking procedure has begun, it should be continued without stopping until completed, subject to weather and conditions beyond the control of the owner/developer.
12.Care shall be taken to ensure that casing pipe installed by boring and jacking method will be at the proper alignment and grade as shown on the approved construction drawings.
13.The owner/developer shall maintain and operate pumps and other necessary drainage system equipment to keep work dewatered at all times.
14.Adequate sheeting, shoring and bracing for embankments, operating pits and other appurtenances shall be placed and maintained to ensure that work proceeds safely and expeditiously. Upon completion of the required work, the sheeting, shoring and bracing shall be left in place, cut off or removed, as designated by the Engineer.
15.Trench excavation, all classes and type of excavation, the removal of rock, muck, debris, the excavation of all working pits and backfill requirements are included under these standards and specifications, Section 470-80.07.
16.All surplus material shall be removed from the right-of-way and the excavation finished flush with the surrounding ground.
17.Grout backfill shall be used for unused holes or abandoned pipes.
18.Any replacement of carrier pipe in an existing casing shall be considered a new installation, subject to the applicable requirements of these standards and specifications.
470-80.24 Free Boring.
A.Where the approved construction drawings indicate a pipeline is to be installed by boring without casing, the owner/developer shall construct the crossing by the free bore method. The free bore method shall be accomplished by the dry auger boring method without jetting, sluicing, or wet boring.
B.The diameter of the free bore shall not exceed the pipe bell outside diameter or the pipe barrel outside diameter plus 1-inch, whichever is greater.
C.Free boring is allowable only under residential driveways. Free boring is not allowed under commercial driveways or any roadway.
D.The owner/developer shall be responsible for any settlement caused by the free bore construction activities.
470-80.25 Concrete Collars.
Concrete collars shall be installed as required on the approved construction drawings and as shown on the standard details.
470-80.26 Inspection and Testing.
A.The scheduled Water System Engineering Technician must be present during testing.
1.Clean and test lines before requesting conditional acceptance. Where any obstruction is met, clean the sewers by means of rods, swabs, or other instruments. When requested by the Engineering Technician, flush out lines and manholes before final acceptance.
2.Alignment: Pipe lines shall be straight and show a uniform grade between manholes. Owner/Developer shall correct any discrepancies discovered during inspection.
3.Watertightness: All sewers constructed shall be tested for watertightness to the maximum extent feasible. Infiltration tests and exfiltration tests shall be performed on all new sewers. In such cases the watertightness of the sewers less than or equal to 24-inches shall be based on a visual inspection. All visible leaks, including those found via television inspection, shall be repaired.
4.Infiltration Tests
(a)Install suitable weirs in manholes selected by the Engineer to determine the leakage of ground water into the sewer. The maximum length of line for each infiltration test shall be 5,000 feet.
Install weir for a minimum of four hours before measuring flow. If leakage in any section of the sewer line exceeds 100 gpd/inch diameter/mile, locate and repair leaks. Repair methods must be approved by the Engineer. After repairs are completed, re-test for leakage.
(b)Furnish, install, and remove the necessary weirs, plugs, and bulkheads required to perform the leakage tests.
(c)Weirs shall be V-notch type equal to Pollard (1-800-437-1146).
5.Exfiltration Tests. Low-Pressure Air Test: Sewer diameters less than or equal to 24-inches.
(a)Prior to air testing, the section of sewer between manholes shall be thoroughly cleaned and wetted. Immediately after cleaning or while the pipe is water soaked, the sewer shall be tested with low-pressure air.
Sewers may be tested in lengths between manholes or in short sections (25 feet or less) using inflatable balls pulled through the line from manhole to manhole. Air shall be slowly supplied to the plugged sewer section until internal air pressure reaches approximately 4.0 psi. After this pressure is reached and the pressure allowed to stabilize (approximately two to five minutes), the pressure may be reduced to 3.5 psi before starting the test. If a 1.0 psi drop does not occur within the test time, then the line has passed the test. If the pressure drops more than 1.0 psi during the test time, the line is presumed to have failed the test, and the owner/developer will be required to locate the leak or leaks, make necessary repairs, and retest the line. Minimum test time for various pipe sizes and types as shown in Table 470.5.
Table 470.5
| Nominal Pipe Size (Inches) | Time | |||
|---|---|---|---|---|
| (Min/100 | ||||
| feet) | ||||
| PVC | DIP | |||
| 6 | 5.7 | 5.7 | ||
| 8 | 7.6 | 7.6 | ||
| 10 | 9.4 | 9.4 | ||
| 12 | 11.3 | |||
| 15 | 14.2 | |||
| 18 | 17 | |||
| 21 | 19.8 | |||
| 24 | 22.8 |
with gradations in 0.1 psi and accuracy of + two percent, shall be provided by the owner/developer. See list of preferred acceptable manufacturers.
(c)The owner/developer shall keep records of all tests made. Copy of such records will be given to the Water System Engineering Technician. Such records shall show date, line number and stations, operator, test pressure, loss and time and pass or fail.
(d)The owner/developer is cautioned to observe proper safety precautions in performance of the air testing. It is imperative that plugs be properly secured and that care be exercised in their removal. Every precaution shall be taken to avoid the possibility of over-pressurizing the sewer line.
6.Deflection Test: All polyvinyl chloride pipe gravity sewers.
(a)Test PVC gravity sewer for excessive deflection by passing a mandrel through the pipe. Deflection of the pipe shall not exceed five percent.
(b)The mandrel size shall be based upon the maximum possible inside diameter for the type of pipe being tested, taking into account the allowable manufacturing tolerances of the pipe. The mandrel shall have an odd number of legs, or vanes, with a quantity of such equal to or greater than nine. The legs of the mandrel shall be permanently attached to the mandrel. A mandrel with variable sizes shall not be allowed. The mandrel shall be constructed of steel or aluminum and shall have sufficient rigidity so the legs of the mandrel will not deform when pulling through a pipe. The mandrel dimensions shall be checked by the Engineering Technician before use by the owner/developer.
Title 3: Chapter 470
(c)Excavate and install properly any section of pipe not passing this test.
Re-test until results are satisfactory.
(d)This test shall be performed twice:
i.Once within the first 30 days of installation, and
ii.Once during final inspection, but no sooner than 30 days after pavement backfill is completed.
7.Closed Circuit Television: The interior of the gravity sewers shall be subjected to a televised inspection. The audio/video tape shall provide an audio description of what is being viewed; provide a continuous running footage indicator between manholes; and be prepared in the presence of the Water System Engineering Technician. Prior to Conditional Acceptance the Water System shall be provided with one electronic copy of the CCTV inspection report showing the entire length of gravity sewer being tested.
The report shall contain the condition of pipe, type of pipe, depth, location of services, length, type joint, roundness, and distance between manholes.
Any pipe found to be cracked, leaking, misaligned, bellied or otherwise defective shall be removed and replaced.
8.Manholes
(a)Prior to testing manholes for watertightness, all lift holes shall be plugged with a non-shrink grout, all joints between precast sections shall be properly sealed and all pipe openings shall be temporarily plugged and properly braced.
(b)Vacuum Tests: The manhole, after proper preparation in Section 470-80.07, shall be vacuum tested prior to or after backfilling. The test head shall be placed at the inside of the top of the cone section and the compression head inflated to 40 psi to affect a seal between the vacuum base and the manhole structure. Connect the vacuum pump to the outlet port with the valve open. A vacuum of 10-inches of mercury shall be drawn and the vacuum pump shut off. With the valves closed, the time shall be measured for the vacuum to drop to 9-inches. The manhole shall pass if the time is greater than that specified in the table below. If the manhole fails the initial test, necessary repairs shall be made with non-shrink grout while the vacuum is still being drawn.
Retesting shall proceed until a satisfactory test is obtained. See list of preferred acceptable manufacturers.
(c)All lines and manholes must be tested no sooner than 30 days after installation.
(d)All lines and manholes must be retested if the final plat has not been approved 180 days after the initial passed tests.
Title 3: Chapter 470
Table 470.6
| 12 14 18 18 20 | 30 35 40 45 50 | 39 48 52 59 65 | 49 57 67 73 81 |
|---|---|---|---|
| 22 24 | 55 59 | 72 78 | 89 97 |
| 26 | 64 | 85 | 105 |
Title 3: Chapter 470
Reading grid · rebuilt for display · verify at source (p. 510) ↗