At the request of the Engineer a complete set of computations, in a tabular form, indicating depths and velocities at minimum, average and maximum daily waste flows for the different sizes of sewers proposed. Size, type, class, thickness and pressure rating of sewers shall be as shown on the approved plans.
6.0.1. 
Depth. In general, sewers shall be sufficiently deep so as to receive sewage from the first floor of all places served by the sewers and to prevent freezing. Minimum cover of sanitary sewers shall be 42 inches, unless approved otherwise.
6.0.2. 
Slope. All sewers shall be designed and constructed to give mean velocities, when flowing full, of not less than 2.0 feet per second. The following are the minimum slopes which should be provided; however, slopes greater than these are desirable.
Sewer Size
Minimum Slope in Ft. per 100 Ft.
8 inch
0.40
10 inch
0.28
12 inch
0.22
14 inch
0.17
15 inch
0.15
16 inch
0.14
18 inch
0.12
21 inch
0.10
24 inch
0.08
27 inch
0.067
30 inch
0.058
36 inch
0.046
Sewers should be laid with uniform slope between manholes. Sewers on 20 per cent slope or greater shall be anchored securely with concrete anchors spaced no more than 36 feet center to center.
6.0.3. 
Sizing. New sewer systems shall be designed on the basis of an average daily per capita flow of sewage of not less than 100 gallons per day. Generally, the main, trunk and outfall sewers shall be designed to carry, when running full, not less than 250 gallons daily per capita contributions of sewage, exclusive of sewage or other waste flow from industrial plants. The Engineer may modify these minimum flow conditions as required by system performance or modeling of future flows in the system.
No sewer shall be less than 8 inches in diameter. Sewer taps and laterals shall not be less than 6 inches in diameter. Cleanouts shall be a minimum of 6 inches in diameter.
Sanitary sewers shall be constructed of the following pipe unless otherwise approved by the Engineer. At cover depths less than 10 feet, any of these pipe types may be used. At cover depths greater than 10 feet, SDR 35 PVC pipe shall not be used. At cover depths greater than 15 feet, no PVC pipe may be used.
6.1.1. 
Reinforced Concrete Pipe. Reinforced Concrete sewer pipe and fittings for sewers shall be minimum Class III. Interior shall be lined with Permite PCS-9043 Type II or approved equal.
6.1.2. 
PVC Pipe (Gravity). Polyvinyl chloride plastic pipe and fittings for gravity sanitary sewers shall be Type PSM SDR-35 or SDR-26 in accordance with ASTM D-3034 and F-679.
Pipes and fittings shall have integral molded bells for bell and spigot type joints with elastomeric ring gaskets providing a water tight seal. Gaskets shall be certified by the manufacturer to be chemically immune to normal sewage and sewer gas and the gasket design arrangement on the bell shall be approved by the Engineer.
All pipe fittings shall be molded or otherwise made as one piece integral units.
Adapters as furnished by the pipe manufacturer shall be used to connect PVC pipe to all other type of pipes of fittings.
PVC pipe shall not be used in any system which may receive industrial waste or materials with temperatures greater than 140 degrees F.
6.1.3. 
Ductile Iron Pipe. Ductile iron pipe for gravity sewers and sewage force mains shall be pressure class 150-350, and shall conform to AWWA/ANSI C150/A21.5. Interior shall be lined with Protecto 401, TNEMEC Series 431 Perma-Shield PL, or approved equal. Pipe fittings shall be mechanical joint Class 250 conforming to ANSI Specification Asl.10 (AWWA C-110) for short body cast iron fittings.
6.1.4. 
High Density Polyethylene Pipe (HDPE). HDPE pipe for sewage force mains shall be 160 psi working pressure, DR11 (DR9 for 4" diameter and smaller), and shall conform to ASTM D-1248 and ASTM D-3350. Fittings shall be molded or fabricated with ends to match system piping.
Unless specifically directed otherwise by the Engineer, not more than 100 feet of trench shall be opened ahead of the pipe laying work of any one crew, and not more than 100 feet of open ditch shall be left behind the pipe laying work of any one crew. Watchmen or barricades, lanterns and other such signs and signals as may be necessary to warn the public of the dangers in connection with open trenches, excavation and other obstructions, shall be provided by and at the expense of the contractor. Conformance to all state highway requirements shall be the responsibility of the contractor when encroachment on highway right-of-way is necessary.
When directed by the Engineer, only one half of street crossings and road crossings shall be excavated before placing temporary bridges over the side excavated for the convenience of the traveling public. All backfilled ditches shall be maintained in such a manner that they will offer no hazard to the passage of traffic. The convenience of the traveling public and property owners abutting shall be taken into consideration. All public or private drives shall be taken into consideration and shall be promptly backfilled or bridged at the direction of the Engineer. Excavated materials shall be disposed of so as to cause the least interference, and in every case the disposition of materials shall be satisfactory to the Engineer. Trenches in which pipes are to be laid shall be excavated in open cut to the depths shown on the approved plans, cut sheets or as specified by the Engineer. Where rock is encountered, is shall be removed to a minimum depth of four (4) inches below the pipe bells.
Unless specifically authorized by the Engineer, trenches shall be in no case excavated or permitted to become wider than 2 feet 6 inches plus the nominal diameter of the pipe at the level of or below the top of the pipe. If the trench does become wider than 2 feet 6 inches at the level of or below the top of the pipe, special precautions may be necessary, such as providing compacted granular fill up to the top of the pipe or providing pipe with additional crushing strength as determined by the Engineer after taking into account the actual trench loads that may result and the strength of the pipe being used. The contractor shall bear the cost of such special precautions as necessary.
Trenches shall be kept free of water during the laying of the pipe and until the pipeline has been backfilled. Removal of water shall be at the contractor's expense.
All sanitary sewer pipes shall be laid using bedding of #9 crushed stone placed to a minimum depth of four inches (4") below the bottom of the pipe barrel. Unstable soil shall be stabilized by over-excavating to allow a layer of #3 crushed stone below the four inches (4") of #9 bedding.
The laying of the sewer pipe in finished trenches shall be commenced at the lowest point so that the spigot or tongue ends point in the direction of flow. Jointing of pipes shall follow the manufacturer's recommended procedures.
Contractors may use a laser instrument to set the grades on sewer lines in lieu of using a grade string and batter boards set from grade stakes. In using such an instrument, the contractor shall be responsible for maintaining grades and elevations as called for on the drawing profiles, and any variances found shall be corrected by the Contractor at his expense.
All pipe lengths shall be laid with ends properly jointed and true to line and grade as approved by the Engineer. They shall be joined to form a sewer with a smooth and uniform invert. Supporting of pipe shall be as set out hereinbefore under "Pipe Bedding" and in no case shall the supporting of pipe on blocks be permitted.
Branches, fittings and specials for sewer lines shall be provided and laid as and where directed by the Engineer or shown on the plans.
Before each piece of pipe is lowered into the trench, it shall be thoroughly inspected to insure it is clean. Each piece of pipe shall be lowered separately unless special permission is given otherwise by the Engineer. No piece of pipe or fittings which is known to be defective shall be laid or placed in the lines. If any defective pipe or fitting shall be discovered after the pipe is laid, they shall be removed and replaced with a satisfactory pipe or fitting. In case a length of pipe is cut to fit in a line, it shall be so cut as to leave a smooth end at right angles to the longitudinal axis of the pipe and a repair type coupling used as a splicing device.
When installation is stopped for any reason, the exposed ends of pipes shall be closed with a plug fitted into the pipe bell, so as to exclude earth or other material, and precautions taken to prevent flotation of pipe by runoff into trench.
In cases where storm sewers, gas lines, water lines, telephone lines, and other utilities, or other underground structures are encountered, they shall not be displaced unless necessary, in which case they shall be replaced in as good condition as found as quickly as possible. Any lines or underground structures damaged in the construction shall be replaced at the contractor's expense, unless in the opinion of the Engineer, such damage was caused through no fault of the contractor.
The contractor shall notify the utility companies prior to excavation adjacent to their facilities.
The contractor's attention is further directed to Section 1.4 for additional requirements.
Where unstable material is encountered or where the depth of excavation in earth exceeds six feet, the sides of the trench or excavation shall be supported by substantial sheeting, bracing or shoring in accordance with applicable regulations. Adequate and proper shoring of all excavations, and design and fabrication of all sheeting and shoring systems shall be the entire responsibility of the Developer.
Care shall be taken to avoid excessive backfill loads on the completed pipelines and the requirements that the width of the ditch at the level of the crown of the pipe be not more than two feet six inches plus the nominal diameter of the pipe shall, as set out in Section 6.2, be strictly observed.
All backfilling shall be accomplished in accordance with the details shown on Standard Drawings.
When directed by the Engineer, the contractor shall add water to the backfill material or dry out the material when needed to attain a condition near optimum moisture content for a maximum density of the material when it is compacted. The contractor shall obtain a compaction of the backfill of at least 95 per cent of standard (ASTM D 698) Procter density.
Where required by the Engineer, impervious check dams shall be installed in pipeline trenches to prevent migration of groundwater along the pipe. At a minimum, these check dams shall be installed at any crossing of a creek or stream, and at one thousand foot (1000') intervals along any run of pipe.
Before final acceptance, the contractor will be required to level off all trenches or to bring up the level of the surrounding terrain. The contractor shall also remove from roadways, rights-of-way, and/or private property all excess earth or other materials resulting from construction.
In the event that pavement is not placed immediately following trench backfilling in streets and highways, the contractor shall be responsible for maintaining the trench surface in a level condition at proper pavement grade at all times.
In all cases walking or working on the completed pipelines, except as may be necessary in compacting or backfilling, will not be permitted until the trench has been backfilled to a point one foot above the top of the pipe. The filling of the trench and the compaction of the backfill shall be carried on simultaneously on both sides of the pipe in such a manner that the completed pipeline will not be distributed and injurious side pressures do not occur.
6.7.1. 
Method "A" Backfilling in Open Terrain. Backfilling of pipeline trenches in open terrain shall be accomplished in the following manner:
The lower portion of the trench, from the pipe bedding to a point 6 inches above the top outside surface of the pipe shall be backfilled with No. 9 crushed stone. This material shall be placed in 6" layers along each side of the pipe taking care to keep the level of fill on each side of the pipe equal. Compaction shall be accomplished by hand-tamping or by approved mechanical methods. Upon approval of the Engineer, crushed stone, fine gravel, or sand may be used as backfill in lieu of compacted earth.
The upper portion of the trench above the compacted portion shall be backfilled with material which is free from large rock. Incorporation of rock having a volume exceeding eight (8) cubic inches is prohibited. Backfilling this portion of the trench may be accomplished by any means approved by the Engineer. The trench backfill shall be heaped over or leveled as directed by the Engineer.
6.7.2. 
Method "B" - Backfilling Under Sidewalks, and Unpaved Driveways. The entire trench shall be backfilled with No. 9M crushed stone.
6.7.3. 
Method "C" - Backfilling Under Streets and Paved Driveways. The lower portion of the trench, from the pipe bedding to a point six inches (6") below the bottom of the pavement or concrete sub-slab shall be backfilled with No. 9 crushed stone or fine gravel.
The upper portion of the trench, from a point 6 inches below the base of the pavement or concrete, shall be backfilled with a base course of dense graded aggregate. At such time that pavement placement is accomplished, the excess base course shall be removed as required.
The testing of sewage force mains and gravity sewers shall be accomplished by the contractor in accordance with the procedures listed hereinafter.
6.8.1. 
Sewage Force Mains. On all projects involving the installation of sewage force mains, the finished work shall comply with the provisions listed below, or similar requirements which will insure equal or better or better results:
a. 
Leakage in pipelines, when tested under pressure of 50 psi in excess of normal operating pressures, shall not exceed 50 gallons per 24 hours per inch of diameter per mile of pipe.
b. 
Where practicable, pipelines shall be tested between line valves or plugs in lengths of not more than 1500 feet.
c. 
Pipelines shall be tested before backfilling at joints except where otherwise required by necessity, local ordinance or public convenience.
d. 
Duration of test shall be not less than two hours where joints are exposed and not less than 24 hours where joints are covered.
e. 
Where leaks are visible at exposed joints and/or evident on the surface where joints are covered, the joints shall be retightened or relayed, and leakage minimized, regardless of total leakage as shown on test.
f. 
All pipe, fittings and other materials found to be defective under test shall be removed and replaced at the contractor's expense.
g. 
Lines which fail to meet tests shall be repaired and retested as necessary until test requirements are complied with.
h. 
Where nonmetallic joint compounds are used pipelines should be held under normal operating pressure for at least three (3) days before testing.
6.8.2. 
Gravity Sanitary Sewer Lines. On all projects involving installation of sanitary sewer lines, the finished work shall comply with the provisions listed below or similar requirements which will insure equal or better results:
a. 
After collecting and/or outfall lines or system have been brought to completion, and prior to final inspection, the contractor will be required to clean all dirt, debris and trash from lines and manholes.
b. 
All lines or sections of lines that are found to be laid improperly with respect to line or grade, that are found to contain broken or leaking sections of pipe, or are obstructed in such a manner that they cannot be satisfactorily corrected otherwise, shall be removed and replaced at the contractor's expense.
c. 
The contractor shall lay sewer lines, including house connections so that the ground water filtration shall not average more than 200 gallons per inch of pipe diameter per 24 hours per mile of sewer.
The length of the main sewers shall be used in making the foregoing computation even though the house connections (from the main sewer to the property line) should be in place and included as a part of the system when infiltration is measured. This requirement may be applied to a portion of the contract work, such as the sewers in a separate drainage area or to a single section of the line between two manholes.
d. 
Prior to acceptance, all sewers shall be tested for leakage. Leakage shall conform to ASTM C-828, as follows:
i. 
Contractor shall flush and clean the line prior to testing to wet the pipe surface and clean out debris. Contractor shall plug all outlets.
ii. 
Calculate the test time for the section in accordance with the Technical Manual.
iii. 
Plug and brace the plugs in all openings in test section.
iv. 
Add air until the internal pressure is raised to approximately 4 psi gage. Allow the pressure to stabilize, and start the test. Record the drop in pressure for the est time. If the pressure drops more than 1.0 psi gage during the test time, the line has failed the test. Report test results to the Engineer.
e. 
In order to test for infiltration, the Engineer may also require exfiltration tests on each section of pipe between manholes after it has been laid out but prior to backfilling of joints. Exfiltration tests shall be conducted by plugging the lower end of the section of sewer to be tested and filling the sewer with water to a point approximately five feet above the invert at the lower end and at least one foot above the pipe at the upper end, observing for leakage at all joints and measuring the amount of leakage for a given interval of time. Exfiltration shall not exceed 110 per cent times the infiltration limits set out hereinbefore. All observed leaks shall be corrected even though exfiltration is within the allowable limits. Exfiltration tests will normally be required for flat sections of sewer that are expected to be below the wet season, ground water table.
f. 
To test for infiltration, the Engineer may also require that the contractor plug the open ends of all lines at the manhole so that measurements may be made at each section of the sewer line. This infiltration test will not be made until the sewer line is completed, and the contractor will be required to correct all conditions that are conducive to excessive infiltration and may be required to relay such sections of the line that may not be corrected otherwise. All observed leaks shall be corrected even though infiltration is within allowable limits.
Manholes shall be installed at the end of each line, at all changes in grade, size or alignment, at all intersections, and at distances not greater than 400 feet (500 feet for 18-inch or larger sewers).
Drop pipes shall be provided for any sewer entering a manhole at an elevation 24 inches or more above the manhole invert. Drop manholes shall be constructed with an outside drop connection, where practical. The entire outside drop connection shall be encased in concrete.
Manholes shall be constructed to the form and dimensions shown on the approved plans Manholes shall be constructed as per the Standard Drawings. They shall be constructed on 3500 psi concrete foundations. Minimum manhole diameter shall be 48 inches.
All connections to manholes or other structures shall be made using a chemical resistant rubber compression diaphragm, precast into the manhole. Diaphragms shall meet the requirements of ASTM C-923.
6.9.1. 
Standard Manholes. The standard manhole shall be six feet or more in depth, measured from the base of the cover frame to the top of the concrete footing and shall be of cone type, top construction as shown on the Standard Drawings.
6.9.2. 
Shallow Manholes. The shallow manholes shall be less than six feet in depth, measured from the base of the cover frame to the invert of the effluent pipe and shall be of flat top construction as shown on the Standard Drawings. Manholes shallower than four (4) feet from the bench to the top of the frame and lid shall replace the flat concrete top with East Jordan catalog No. V-7048, or Neenah Foundry catalog No. R-1740-F with access lid in the center of the casting.
6.9.3. 
Plastic Adjusting Rings. Plastic adjusting rings shall be round, injection molded high density polyethylene (HDPE) adjustment rings as manufactured by LADTECH, Inc. or approved equal, and shall be traffic rated AASHTO HS-20. Adjustment rings shall be molded from 100% recycled material.
6.9.4. 
Precast Concrete Cones. Precast concrete cones shall be concentric, of the size and shape shown on the plans, and shall conform to the ASTM C478.
6.9.5. 
Manhole Inverts. Manhole inverts shall be formed from 3500 psi concrete as shown on Exhibit.[1] Curved invert shall be constructed of concrete, as shown, and shall form a smooth, even half-pipe section as shown. The inverts shall be constructed when the manhole is being built using prefabricated forms.
The excavation shall be kept free of water while the manhole is being constructed and the manhole shall not be backfilled until inspected by the Engineer.
[1]
Editor's Note: The Exhibits are included as an attachment to this chapter.
6.9.6. 
Manhole Frames and Covers. Unless otherwise approved manhole castings shall consist of cast iron frames and 22 - 3/4 inch diameter covers, weighing not less than 300 pounds per frame and cover, dimensioned as shown on the plans. Manhole covers must sit neatly in the rings, with contact edges machined for even bearing and tops flush with ring edge. They shall have sufficient corrugations to prevent slipperiness. The lids shall have two pick holes about 1-1/4 inches wide and 1/2 inch deep with 3/8 inch undercut all around. Lids on sanitary sewer manholes must not be perforated.
6.9.7. 
Drops into Standard Manholes. Drops into standard manholes shall be built as per the Standard Drawings. Internal drops are permissible as shown on the Standard Drawings.
6.9.8. 
Manhole Testing. All manholes shall be subjected to a vacuum test in accordance with ASTM C1244, except as specified otherwise herein. Manholes shall be tested after installation with all connections in place, and shall include testing of the seal between the frame and the concrete cone, slab or grade rings. A vacuum of at least ten inches of mercury (10" Hg) shall be drawn on the manhole. The manhole shall be considered to pass the test if the vacuum reading does not drop more than one inch Hg (from 10" to 9" Hg) during the minimum test time. Minimum test time is based on manhole diameter and manhole depth, as specified in the applicable Technical Manual.
Approved taps shall be installed on the public sewer for all house or building connections at locations established by the developer's engineer. At least one connection shall be provided for each platted lot. The contractor shall lay the service laterals from this point to the property line, or easement line. The developer shall place a cap on the end of the service lateral and use a metallic marker with PVC pipe and cap around it for protection. This marker should be even with the ground. The developer is not required to install the tee and cleanout, unless so directed by the Engineer during plan review.
Sanitary sewer tap clean-outs and service connections shall be installed in accordance with the plans and details by a qualified plumber. Clean-outs shall be 6-inch minimum in diameter and have cast iron covers installed according to the standard drawings.
Each separate dwelling structure, commercial building or industrial building shall be provided with a separate service lateral. All connections which service single family dwellings shall be not less than 6 inch in diameter pipe. All connections which service multi-family dwellings, or commercial and industrial buildings shall be sized based on occupancy or use. Trenching, pipe installation and backfilling shall conform to the requirements set out herein. All open ends of service laterals shall be sealed with a standard PVC plug or cap, with compression joints compatible with the pipe.
Service laterals shall be PVC (polyvinyl-chloride) sewer pipe, ASTM D-3034, latest revision, or ductile iron pipe, AWWA specification C-151 cement lined, and shall meet requirements of the state plumbing code. Any part of a service lateral that is located within five (5) feet of a water service pipe shall be constructed with ductile iron pipe, unless the service lateral is at least one (1) foot deeper in the ground than the water service line. Ductile iron pipe may be required where the service lateral is exposed to damage or stoppage by tree roots. Ductile iron pipe shall be used in filled or unstable ground, in areas where the cover over the service lateral is less than three (3) feet, or in areas where the sewer is subject to vehicular or other external loads.
Under normal conditions service laterals shall be laid on a slope of not less than two percent (approximately 1/4 inch per foot). A minimum grade of one percent may be used with the approval of the Engineer.
The tapping of service laterals into manholes on the newly constructed sewers will not be permitted, except as permitted by the Engineer. Where it is necessary to do so, the invert of the service lateral shall not be higher than a point three inches below the top of the bench in the manhole and suitable trough shall be provided in the bench to prevent the accumulation of solids on the bench. If necessary, a standard drop connection shall be provided for a house service that is tapped into a manhole.
The installation of service laterals shall follow immediately or be concurrent with the construction of the main sewer.
Connection to existing gravity sewer lines shall be made where indicted on the plans. All connections to existing sewers shall be performed by HWU personnel, with costs to be borne by the developer in accordance with utility standard operating procedures.
6.12.1. 
Concrete Sidewalks, Curbs and Gutters. Where concrete sidewalks, curbs or gutters are cut or disturbed during the construction work, they shall be removed to limits as directed by the Engineer, and shall be replaced in fully as good or better condition than that which existed prior to the contractor's operation.
When replacing concrete sidewalks, existing sidewalk shall be removed to the edge of the next panel. The developer shall install 1/2 inch premolded full-depth expansion material at the exposed edges of existing concrete, and at intervals not to exceed 40 feet.
Sidewalk shall be formed, poured and cured in conformance with Section 4.2 of these specifications. Curbs and Gutters shall be formed, poured and cured in conformance with Section 4.3 of these specifications.
6.12.2. 
Concrete Pavement. Where Portland Cement concrete streets, alleys and driveways are removed, they shall be reconstructed to the original lines and grades and in such manner as to leave all such surfaces in fully as good or better condition than existed prior to the operation.
The existing concrete paving shall be sawed or cut to straight edges 12 inches outside the edges of the trench or removed to an existing joint as directed by the Engineer.
Concrete pavement shall be formed, poured and cured in conformance with Section 3.5 of these specifications.
6.12.3. 
Bituminous Highway, Street and Driveway Replacement. The contractor shall replace those sections of existing alleys, streets and driveways which have been removed during construction. He shall reconstruct same to the original lines and grades and in such manner as to leave all such surfaces in fully as good or better condition than that which existed prior to his operation.
Prior to trenching, the pavement shall be scored or cut to straight edges at least 12 inches outside each edge of proposed trench to avoid unnecessary damage to the remainder of the paving. Edges of the existing pavement shall be recut and trimmed to square, straight edges after the pipeline has been installed and prior to placing the new base and pavement.
Backfilling the trench shall be in accordance with the previous section on backfilling trenches. Base course for the paving shall be Dense Graded Aggregate and shall be placed in accordance with section 3.4 to a depth equal to the existing base course, but not less than 6 inches in streets and alleys, and 4 inches in driveways.
Pavement shall be replaced in conformance with Section 3.4 of these specifications.
Concrete cradle, anchors or encasement of sewer lines and/or fittings are discouraged and shall only be placed where shown on the plans, required by the specifications, or as directed by the Engineer. Concrete shall be Class "B" and shall be mixed sufficiently wet to permit it to flow under the pipe to form a continuous bed. In consolidating concrete, care shall be taken not to disturb the grade or line of the pipe or injure the joints. See standard drawing.
6.14.1. 
Horizontal Separation. Sewers should be laid at least 10 feet, horizontally, from an existing or proposed water main. Should local conditions prevent a lateral separation of 10 feet, a sewer may be laid closer than 10 feet to the water main if:
a. 
It is laid in a separate trench.
b. 
It is laid in the same trench with water mains located on one side on a bench of undisturbed earth.
c. 
In either case, the elevation of the top of the sewer is at least 18 inches below the bottom of the water main.
6.14.2. 
Vertical Separation. Whenever sewers must cross under water mains, the sewers shall be laid at such an elevation that the top of the sewer is at least 18 inches below the bottom of the water main. When the elevation of the sewer cannot be buried to meet the above requirements, the sewer line shall be reconstructed with ductile iron pipe for a distance of 10 feet on each side of the water line. One full length of water main shall be centered over the sewer so that both joints will be as far from the sewer as possible.
Existing mail boxes, drainage culverts, clothes line posts, fences, and the like shall not be disturbed unless necessary, in which case, they shall be replaced in as good condition as found as quickly as possible. Existing materials shall be reused in replacing such facilities when materials have not been damaged by the contractor's operations. Existing facilities damaged by the contractor's operations shall be replaced with new materials of the same type at the contractor's expense.
Casing pipe shall be steel, plan end, coal tar enameled, mill coated inside and out. The steel pipe shall have welded joints and be at least 18 foot lengths. The wall thickness of the pipe shall be at least 1/4 inch.
Upon completion of the installation of the sewer pipes and appurtenances, the contractor shall remove all debris and surplus construction materials resulting from the work. The contractor shall grade the ground along each side of the pipe trench in a uniform and neat manner leaving the construction area in a shape as near as possible to the original ground line.
Unless otherwise specified by the Engineer, all graded areas shall be left smooth and sown with a mixture of grasses at a rate of not less than 100 pounds per acre. Seed mixture shall be as specified in Section 2.9. When final grading has been completed, the area to be seeded shall be fertilized with number 12-12-12 fertilizer at a rate of 1000 lbs. per acre. Agricultural limestone shall be added at a rate of 3 tons per acre. After the fertilizer and agricultural limestone have been distributed, the contractor shall disc or harrow the ground to thoroughly work the fertilizer into the soil. The seed shall then be broadcast either by hand or by approved sowing equipment. After the seed has been distributed, the contractor shall then lightly cover the seed by use of a drag or other approved device. All seed shall be certified. The seeded area shall then be mulched with clean, weed-free straw to a depth of approximately 2 inches. Any necessary reseeding or repairing shall be performed by the contractor prior to final acceptance.
When sodding is required, it shall be so laid that no voids occur between strips. Weed roots shall be removed as the sod is laid, and the finished surface shall be true to grade even and equally firm at all points. Well screened topsoil shall be lightly sprinkled over the sodded areas and shall be raked to insure sealing the sod joints. The sodded areas shall be thoroughly watered.