2024 Design and Construction Standards - Section 3 - Force Mains

10 SECTION 3 – FORCE MAINS 1 Design 11 General A All engineering plans must meet the minimum design criteria of the State 15A NCAC 2T Regulations “ Waste Not Discharged to Surface Waters ” and the County Johnston County Water Distribution , Wastewater Collection , and Reclaimed Water Design and Construction Standards , whichever is more stringent B All submittals , construction drawings , specifications and as - built drawings shall meet the minimum criteria stated in Section 8 - Certifications , Submittals and Inspections of this Document 12 Location A All force mains are to be installed within the dedicated street rights - of - way a minimum 5 ’ from the right - of - way where possible Utility easements shall be provided for all exceptions Force mains within the street right - of - way shall be a minimum of 5 - feet from the edge of the street pavement or back of curb Force mains within the NC DOT right - of - way or in an easement immediately adjacent to a NC DOT right - of - way shall be installed at a depth of 3 - feet below the edge of pavement of the road of 3 - feet below grade , whichever is deeper for pipelines 8 - inches in diameter and smaller Force mains greater than 10 - inches in diameter shall be installed 3 ½ - feet below the edge of pavement of the roadway or 3 ½ - feet below grade , whichever is deeper B Force mains within easements are to be installed approximately 5 - feet from the easement boundary and a minimum of 10 - feet horizontally , measured wall to wall , from existing or proposed waterlines C Force mains shall be installed a minimum of 5 - feet horizontally , measured wall to wall , from existing and proposed storm drain and natural gas lines D No permanent structures or other utilities shall be installed over force mains or within utility easements associated with force mains without prior consent of the County 13 Size A Force mains shall be sized to initially maintain a minimum velocity of 2 - feet per second when pumping Initial pumping velocity shall not exceed 4 - feet per second to allow for upsizing of pumps and impellers in the future B Force mains shall not exceed a velocity of 6 - feet per second without consent of the County 14 Valves A Main Line Valves - Main line valves shall be installed at locations determined by the Engineer and shown on plans Valves shall be of the resilient wedge gate type conforming to AWWA C - 509 Valves shall be rated for 150 psi minimum All valves larger than 12 - inch or Section 3 - 1 FORCE MAINS 2024 RevisionPageSECTION 3 – FORCE MAINS installed at a depth 8 - feet or greater shall be enclosed in a manhole Divisional valves shall be installed approximately every 3,000 LF B Air Release Valves - Air Release Valves shall be required on all mains which have a change in elevation of 10 - feet or greater Air release valves shall be installed at the highest point within that elevation change 2 Materials 21 General A All material and appurtenances shall meet the following minimum standard requirements therefore B Pipe shall be of the type , size , class and diameter as hereinafter specified and called for by the Plans and or Bid C Force mains shall be PVC except where special conditions require ductile iron or HDPE material The use of ductile iron pipe must be approved by the county D Trench width or buried pipe design shall be considered as the outside diameter of the pipe plus 2 - feet , at the bottom and up to one foot above the top of the pipe E Buried pipe shall be designed for laying condition E to withstand all internal pressures and external loads with a minimum depth to cover of 3 - feet for pipelines 8 - inches and smaller in diameter , a minimum cover of 3 - ½ - feet for pipeline 10 - inches and larger in diameter , and greater depths of cover where required by the Plans , plus an H - 20 live load in accordance with AASHTO specifications In wet areas pipe shall be bedded in stone to spring line The depth of cover shall be measured from edge of pavement or finished grade , whichever is deeper If the force main is installed in the bottom of the ditch , the depth of cover shall be measured from the bottom of the ditch F Design pressure shall consist of 150 psi working pressure plus 100 psi surge allowance for force mains designated for 150 psi working pressure , or proportionately higher pressures for higher operating conditions G Pipe diameters shall be the minimum net inside diameter of the pipe after any required lining is placed , with a maximum tolerance of 1 4 - inch on the minus side , for sized through 36 - inches diameter H All fittings shall be of at least the same class as the pipe with which they are used Ductile iron mechanical joint fittings shall be used with all ductile iron pipe , and PVC pipe 4 - inch or larger in diameter Ductile iron pipe shall be coated on the interior with Sewper Coat as manufactured by Lafarge Calcium Aluminate or Protecto 401 ceramic lining as manufactured by US Pipe or approved equal minimum of one joint I All valves shall have standard mechanical joint ends , except where flanged or other type ends are specifically required Flanges , where required , shall be furnished with operating nuts , or handwheels as necessary All valves shall be of at least the same class of the pipe with which Section 3 - 2 FORCE MAINS 2024 RevisionPageSECTION 3 – FORCE MAINS they are used A valve box shall be provided for each underground valve Concrete pipe vaults , precast manholes , with cast iron cover shall be provided for all air valves 22 Ductile Iron Pipe A Ductile iron pipe shall be centrifugally cast of ductile iron having a minimum tensile strength of 60,000 psi , a minimum yield strength of 42,000 psi , and a minimum elongation of 10 percent Grade 60 - 42 - 10 It shall be designed , manufactured , and shall conform to the requirements of ANSI A2151 AWWA C151 Standards , for a minimum of 150 psi operating pressure plus a minimum allowance of 100 psi for surge B Nominal laying lengths shall be 18 or 20 - feet nominal maximum of 20 percent of each size for each order being as much as 24 - inches shorter than the nominal laying length and additional 10 percent as much as 6 - inches shorter than nominal laying length C Exterior buried pipe joints shall be either mechanical or push joint type with retainer glands except where flanged ends are required for interior piping D Dimensions shall conform to the requirements of ANSI A216 , ANSI A218 , ANSI A2111 , and WW - P - 421 C , as applicable Dimensions shall be gaged at sufficiently frequent intervals to assure dimensional control 1 Insides of sockets and outside of spigot ends shall be tested with circular gages E Wall thickness shall be determined for the design working pressure and depth of cover shown in accordance with ANSI A2150 - 1976 Minimum allowable wall thickness shall be Class 50 F All pipes shall be tested at the factory in accordance with ANSI requirements for each type G Each pipe shall be coated on the outside with standard bituminous coating of either coal - tar or asphalt base approximately one mil thick 1 The coating shall be continuous , smooth , and strongly adherent to the pipe and shall not become brittle from cold or sticky from heat H Ductile iron pipe shall be coated on the interior with SewperCoat as manufactured by Lafarge Calcium Aluminates or Protecto 401 ceramic lining as manufactured by US Pipe or approved equal I Where a ductile iron pipe discharges into a manhole or wet well , a minimum of one joint must be coated on the interior as specified herein 1 At air release valves a minimum of 10 linear feet of ductile iron with interior coating must be installed J Each pipe shall be weighed prior to placing of the inside lining Weight , nominal thickness , sampling period , and class of pipe shall be shown on each pipe The manufacturer’s year of production and the letters DI or DUCTILE shall be clear and legible and on , or near , the bell end Pipe without these markings shall be rejected Section 3 - 3 FORCE MAINS 2024 RevisionPageSECTION 3 – FORCE MAINS 23 Polyvinyl Chloride Pipe A PVC pipe shall be rigid polyvinyl chloride with integrally formed , factory fabricated , or twice gasketed coupling type , for rubber ring type joints B It shall be suitable for all conditions imposed by Plan locations and for a minimum working pressure of 150 psi at 73 ° F C Pipe shall be Type I , Grade I , made from clear virgin material and shall conform to the requirements of Commercial Standard C5 256 , ASTM D1784 , ASTM D2241 and with standard dimension ratio SDR 21 for pipeline diameter 8 - inches and smaller D All force mains greater than 8 - inches in diameter shall meet all requirements of AWWA Specifications C - 900 or C - 905 , DR 25 E All pipe shall bear the National Sanitation Foundation Seal of Approval , the manufacturer’s name , and the class of pipe F Provisions must be made for expansion contraction at each joint , through the rubber gasket and pipe bell Laying lengths shall be 20 - feet ± 1 - inch , or 38 - feet ± 1 - inch except that , random lengths may be furnished for special connections and other special uses G Stored PVC pipe shall be exposed to sunlight for no more than ninety 90 days Any excess pipe stored on - site for more than thirty days shall be covered with an opaque tarpaulin and means shall be provided for heat dissipation and ventilation Pipe discolored due to sunlight exposure shall not be installed as part of the County’s system The County representative shall determine the suitability of exposed pipe H The installation date for all PVC pipe shall be no later than one year from the date of manufacture as stamped on the pipe 24 Fusible PVC A Fusible PVC pipe shall conform to AWWA C900 , AWWA C905 , ASTM D2241 or ASTM D1785 for standard dimensions , as applicable Testing shall be in accordance with the referenced AWWA standards for all pipe types Fusible PVC pipe shall be extruded with plain ends The ends shall be square to the pipe and free of any bevel or chamfer There shall be no bell or gasket of any kind incorporated into the pipe Fusible polyvinylchloride pipe shall be manufactured in a standard 40 - feet nominal length , or custom lengths as specified 1 Pipe shall be marked as follows a Nominal pipe size b PVC c Dimension Ratio , Standard Dimension Ratio , or Schedule d AWWA pressure class , or standard pressure rating for non - AWWA pipe , as applicable e AWWA standard designation number , or pipe type for non - AWWA pipe , as applicable f Extrusion production - record code Section 3 - 4 FORCE MAINS 2024 RevisionPagePage pageNumber5SECTION 3 – FORCE MAINS g Trademark or trade name h Cell Classification 12454 and or PVC material code 1120 may also be included 2 Pipe shall be homogeneous throughout and be free of visible cracks , holes , foreign material , blisters , or other visible deleterious faults 25 Steel Encasement Pipe A Encasement pipe for installation under highways and railroads , shall be spiral welded steel pipe conforming to ASTM Specifications A252 - 61 , Grade 2 Encasement pipe shall conform to NCDOT Specifications for pipe laying for highway crossings and to AREA Specifications for railroad crossings The pipe shall be furnished with a bituminous coating on the outside B Carrier Pipe AWWA C - 900 905 with locking gaskets or approved equal meeting all PVC requirements set forth in section 23 C Spacers – Stainless steel spacers shall be used to position and stabilize the carrier pipe A minimum of four 4 spacers per joint shall be installed 26 Ductile Iron Fitting A Ductile cast iron fittings shall conform to the requirements of ANSI Specification A2110 , with mechanical joint ends conforming to ANSI Specification A339 , Grade 80 - 60 - 3 All ductile iron fittings shall be Protecto 401 lined and coated with the exception of sleeves All fittings shall be coated on the outside and inside as required for pipe Where flanged ends may be required , flanges shall conform to applicable requirements of ANSI B161 and ANSI B16B Ductile iron pipe shall be coated on the interior with Sewper Coat as manufactured by Lafarge Calcium Aluminate or Protecto 401 ceramic lining as manufactured by US Pipe or approved equal minimum of one joint 27 Joint Material A Gaskets for pipe and fittings shall be continuous rings of rubber material compounded to resist deterioration and a texture to assure a permanent and watertight seal They shall have smooth surfaces , free from pitting , blisters , porosity or any other defects Gaskets shall conform to the requirements of AWWA Specification C111 A2111 B Gasket lubricant shall be a potable hydrogenated vegetable oil , insoluble in cold water , non - toxic and shall not support the growth of bacteria It shall contain no deleterious ingredients and shall have no deteriorating effects on the gaskets The lubricant shall be semi - paste , easily applicable , readily adherent to the inside of the bell and shall remain in an unstable state throughout the range of temperature in which pipe is normally installed Lubricant shall be delivered to the job site in unopened containers bearing the manufacturer’s name and trade name or trademark Section 3 - 5 FORCE MAINS 2024 RevisionPagePage pageNumber6SECTION 3 – FORCE MAINS 28 Plug Valves A Plug valves shall be non - lubricated , eccentric type with resilient seat seal Valves shall meet or exceed the testing requirements of AWWA C517 B Valve bodies shall be of ASTM A536 ductile iron cast with integral piping connections Bodies shall have a minimum 30,000 psi tensile strength The interior of the valve body shall be coated with an epoxy lining C Valves shall be off - set disc type with a minimum port area of 100 full pipe area The valve shall be fully serviceable at full line pressure The valve bonnet cover shall be removable for inspecting and repacking the plug and seat while the valve is installed in the pipeline Connecting hardware shall be type 316 stainless steel D Body seats shall be non - jamming , continuous interfacing type with 360 - degree seating Screw in body seats are not acceptable Body seat materials shall be welded nickel alloys with a minimum nickel content of 95 or type 316 stainless steel E Resilient seat seals shall be of Buna - N or Neoprene , suitable for use in sewage service Seat coating shall be thermally bonded and in conformance to AWWA Standard C550 F Bearings shall be stainless steel , have a minimum working pressure of 150psig , and be permanently lubricated G Valve seats shall be tested and provide leak - tight shut - off to 175 psi for valves 3 - inches - 12 - inches and 150 psi for valves 14 - inches - 72 - inches , with pressure in each direction A hydrostatic shell test at twice rating shall be performed with plug open to demonstrate overall pressure envelope integrity The manufacturer shall certify that the valve shows zero leakage for a period of five minutes at the minimum working pressure H Plug valves 6 - inches and larger shall have gear actuators fully enclosed in a suitable housing to prevent entry of dirt and water into the actuator Gear actuators shall run in a lubricant with seals provided on all shafts A suitable stop shall be set to provide watertight shut - off in the closed position at rated pressure I Buried valves shall be mechanical joint ends complying with ANSI AWWA C111 A2111 Buried valves shall include worm gear operators with a 2 - inch operating nut Above ground valves shall be flanged in compliance with ASME B161 and B1642 Above ground valves shall include worm gear operators with hand wheels J Plug valves in the horizontal position shall be installed with the step horizontal and the plug opening to the crown of the body Plug valves shall be install to orient the plug at the top when closed on vertical piping 29 Gate Valves A Gate valves shall be cast iron body , resilient wedge type , bronze fitted with non - rising stem and provided with suitable stem seals They shall comply with AWWA C509 , designed for a minimum operating pressure of 150 psi All valves shall open counter - clockwise Section 3 - 6 FORCE MAINS 2024 RevisionPagePage pageNumber7SECTION 3 – FORCE MAINS 210 Check Valves A Check valves shall be iron body bronze mounted A Clapper Hinge Pin 316 Stainless Steel is required The body and clapper seating surface must be metal to metal or resilient to metal They shall comply with AWWA C508 , ANSI B161 Class 125 , ANSI ASTM A123 , and A153 Cushioned check valves are required for high heads 75feet TDH and above 211 Air Release Valves A Air valve and vent inflow preventer assemblies for portable water distribution system and storage facilities shall conform to the requirements of ANSI C512 Air release valves shall be combination air valves incorporating the functions of an air and vacuum valve with those of a pressure air release valve in a single housing The combination valve shall be designed to release accumulations of air at high points within a pipeline by exhausting large volumes of air as the pipeline is being filled and by releasing accumulated pockets of air while the pipeline is in operation and under pressure Combination air valves shall also be designed to permit large volumes of air to enter the pipeline during pipeline drainage B Valve shall be 2 - inch minimum 1 Valve body shall be stainless steel or reinforced nylon with 2 - inch threaded inlet 2 All internal metal parts shall be made of 316 stainless steel 2 3 Minimum orifice size shall be 0012 - inches 4 Valves shall be suitable for a working pressure specified by the engineer and tested to a minimum 200 psi 5 Valves shall be ARI model D - 020 , ARI model D - 025 , or approved equal C On pipelines 8 - inches and smaller use C - 900 service tee to installed all air release valves , as manufactured by Harco or equal , with stainless steel valves Stainless steel shall be a minimum of grade 316 D On pipelines greater than 8 - inch , a stainless - steel tapping sleeves saddles Romac 305 or approved equal , stainless steel nipples and stainless - steel valves are required on air release valves Stainless steel shall be a minimum of grade 316 E Valves shall be installed in minimum 5 - foot diameter precast flattop manhole with one joint C900 C905 PVC pipe centered in manhole The interior of manholes shall be coated with at least 50 mils surface dry epoxy sealer prime and finish coating approved by the County Shop drawing material specifications of the coating material must be supplied to the County for approval ARV shall be designed to operate at operating pressure specified by the Engineer Force main shall be installed at sufficient depth through high points so that the ARV manhole is flush with finished grade 212 Valve Boxes A Valve boxes shall be of cast iron , three - piece , screw type with covers and bases They shall be suitably sized for the valve with which they are used and fully adjustable for depth of Section 3 - 7 FORCE MAINS 2024 RevisionPagePage pageNumber8SECTION 3 – FORCE MAINS setting , extension pieces being furnished where necessary Drop type covers shall be provided for each box with the word “ SEWER ” designating the valve service cast into its top surface Brick bases shall be provided and shall be so designed to fully support the box without weight of the box or superimposed load being transmitted to any part of the valve or adjacent pipe on either side B All valve boxes and lids shall be the same size and interchangeable with the County’s existing valve box C A circular precast concrete collar shall be installed around all valve boxes 213 Valve Markers A Valve markers shall be as shown on the detail and of concrete , reinforced as shown Concrete shall be of a mix design to produce a 3,000 - psi compressive strength at 28 days They shall be marked with recessed letters , either MV , AV , or BO In subdivisions or residential areas , the valve markers shall be no more than 10 - inch above grade Valve markers in all other areas shall be no more than 18 - inch above grade The markers shall be installed so all letters on the markers may be read 214 Concrete A Concrete for protection and thrust blocks shall be composed of Portland Cement , sand , course aggregate , water and such admixtures as may be allowed , in such proportions as to provide a minimum compressive strength of 3,000 psi The source of concrete and mix design shall be approved by the County prior to use 215 Crushed Stone A Crushed stone for pipe bedding shall conform to ASTM C33 , size no 67 with a range of 1 4 - inch to 1 - inch 216 Electronic Marker Balls A Electronic location markers shall consist of 4 - inch marker balls having a passive device capable of reflecting a specifically designated repulse frequency , unique to the utility being installed B The marker ball will contain a passive - tuned antenna , molded inside a plastic disk , which is free - floating inside a water - resistant polyethylene shell The shell shall be impervious to minerals , chemicals and temperature extremes C Marker balls shall be color coded in accordance with the American Public Works Association’s utility location and coordinating council standards D Electronic marker balls shall be as manufactured by 3M Telecom Systems or equal E Green electronic marker balls specifically designed for sewer installations shall be used Section 3 - 8 FORCE MAINS 2024 RevisionPagePage pageNumber9SECTION 3 – FORCE MAINS F Marker balls shall be installed approximately 6 - inch over the point to be located , and a minimum of 6 - inch from any metal objects G Marker balls shall be installed while pipe is being laid and shall be placed directly over the pipe H Burial shall not be less than 18 - inch nor more than 2 - feet I Ball markers to be hand backfilled to 1 - foot above ball marker as to prevent movement or damage J The maximum depth for marker ball burial shall be 2 - feet K Electronic marker balls shall be installed at the following locations 1 On ductile iron and PVC pipe 2 At a minimum of every one hundred linear feet directly over main line 3 At bends 22 and ½ degrees and larger 4 At capped or plugged ends 5 At tees over main line 6 At reducers 217 Marker Tape Tracer wire A Marker Tape to be installed on all force mains lines B Marker Tape to be laid in the same ditch to the side of the pipe no more than 1 - foot from the pipe , secured to the pipe every 25 - feet , and with a minimum cover of 2 - feet deep C Tracer stations shall be installed at intervals no less than 300 - feet a part or from other above ground conductive appurtenances D Tracer stations shall be housed in a valve box labeled TS E The tracer wire shall be # 12 copper wire F The tape shall be fastened to the inside of valve box with 3 - feet of excess wire in the box for connectivity G All tracer wire installed in steel encasements shall be inspected and tested to ensure that no damage occurred during installation 3 Installation , Inspection , and Testing 31 Installation A Location 1 Pipework shall be installed at the locations shown on the Plans and to the position , alignment , and grade shown thereon Prior to beginning work at any location , the Contractor shall consult with the Engineer and Owner to determine that all rights - of - way , easements , permits , or other legalities are in order He shall familiarize himself with all conditions and or limitations of such rights - of - way , easements and permits and shall fully comply with all such requirements All work shall be confined to rights - of - way , easements or permit limits and Section 3 - 9 FORCE MAINS 2024 RevisionPage0SECTION 3 – FORCE MAINS any encroachment beyond such limits shall be the Contractors liability All locations must meet the minimum requirements required by the State in 15A NCAC 2T 0305 B Relation of Wells to Sewer 1 In accordance with State 15A NCAC 2T 0305 , the minimum separation from a private well shall not be less than 25 - feet , and the minimum separation from a public water supply well shall not be less than 50 - feet Water main standards for piping material and testing methods must be used in cases where the separation is less than 100 - feet from a well C Relation of Water Main to Sewer 1 Water mains shall be laid at least 10 - feet laterally from existing or proposed sewers measured wall to wall , unless local conditions or barriers prevent a 10 - foot lateral separation , in which case 1 the water main shall be laid in a separate trench , with the elevation of the bottom of the water main at least 18 - inches above the top of the sewer ; or 2 the water main shall be laid in the same trench as the sewer , with the water main located at one side on a bench of undisturbed earth and with the elevation of the bottom of the water main at least 18 - inches above the top of the sewer 2 Crossing a sewer under a water main Crossings A water main that crosses a sewer shall be laid a minimum vertical distance of 18 - inches from the outside of the water main and the outside of the sewer , either above or below the sewer , with preference to the water main located above the sewer One full length of water pipe shall be located so that both joints will be as far from the sewer as possible 3 Any deviation from the above separation requirements will only be allowed by the County after the alternate design has been approved by the NC Department of Environmental Quality D Relation of Reclaimed Water Main to Sewer 1 Crossing a Force Main under a Reclaimed Water Main Whenever it is necessary for a force main to cross under a water main , the force main shall be laid at such an elevation that the top of the force main is at least 18 - inches below the bottom of the water main , unless local conditions or barriers prevent an 18 - inch vertical separation , in which case the water main and sewer shall be constructed of ferrous materials and with joints that are equivalent to water main standards for a distance of 10 - feet on each side of the point of crossing 2 Crossing a Force Main over a Reclaimed Water Main Whenever it is necessary for a force main to cross over a water main , both the water main and the sewer shall be constructed of ferrous materials and with joints equivalent to water main standards for a distance of 10 on each side of the point of crossing A section of force main pipe shall be centered at the point of crossing Section 3 - 10 FORCE MAINS 2024 RevisionPage1SECTION 3 – FORCE MAINS 3 Force mains shall not be laid within 2 - feet horizontal from a reclaimed water main If 2 - feet separation cannot be maintained , the following conditions must apply a The reclaimed water main is laid in a separate trench , with the elevation of the bottom of the reclaimed water main at least 18 - inches above the top of the sewer ; or b The reclaimed water main is laid in the same trench as the sewer with the reclaimed water main located at one side on a bench of undisturbed earth , and with the elevation of the bottom of the water main at least 18 - inches above the top of the sewer E Stream Crossing 1 Force mains shall be routed such that the number of stream crossings minimized When a stream crossing is required by the design , the crossing shall be as nearly perpendicular to the stream flow as possible 2 Open cut or horizontal directional drill C - 900 905 with joints equivalent to water main standards With open cut , watertight ferrous encasement pipe , restraints and spacers as described in section 25 C shall be used to construct force mains that cross streams The encasement pipe shall be extended horizontally for a length equal to that required by 15A NCAC 2T 0305 f either side of the stream 3 Force main bedding , haunching , and backfill shall be appropriate for the installation location and pipe material However , the ability of the bedding and backfill material to readily erode , cause siltation , damage the force main during installation , and corrode the force main after installation shall also be considered F Wetland Separation 1 Rule 15A NCAC 2T 0305 provides design criteria for sewer line extensions including required separation distances The rule requires that sewer systems be located at least 50 feet away from all wetlands and provides alternative criteria for instances when the setback cannot be maintained The following provisions are relevant to this policy a f The following minimum separations shall be provided for the sewer system except as allowed by Paragraph g of this Rule i Waters classified WS except WS - I or WS - V , B , SA , ORW , HQW , or SB from normal high water or tide elevation and wetlands … 50 feet b g Alternatives where separations in Paragraph f of this Rule cannot be achieved c 5 For all other separations , materials , testing methods and acceptability standards meeting water main standards 15A NCAC 18C shall be specified 2 While the rule provides alternatives for piping material when the separation to wetlands cannot be met , the rule does not address manholes and pump stations In accordance with the Section 3 - 11 FORCE MAINS 2024 RevisionPage2SECTION 3 – FORCE MAINS provision for alternative design covered under 15A NCAC 2T 0105 n , adherence to the following criteria shall be considered equivalent to the Rule 0305 f a Sewer systems shall be designed to maintain maximum feasible separations when a 50 - foot separation cannot be met b With regards to pump stations serving a single building i Pump stations shall be of a type specifically engineered to be watertight in floodplain conditions including watertight lids ii Wet wells shall be constructed of either high density polyethylene or fiberglass reinforced polyester resins with all seams thermally welded and factory tested iii All necessary penetrations shall be factory sealed and tested No field penetrations will be allowed iv The pump station shall be located no further than 50 feet from the building served and shall be vented back to the building v All pump station wet wells shall maintain a separation of no less than 10 feet from wetlands c All other pump station wet wells shall be located a minimum of 50 feet from wetlands d With regards to manholes i Manholes shall be provided with a watertight frame and cover with gasket ii All manhole seams shall be externally taped sealed iii Manholes shall be provided with a full waterproof interior coating lining iv Watertight pipe connections shall be provided consisting of a flexible rubber boot or compression type connector v All manholes shall be tested in accordance with ASTM C1244 “ Standard Test Method for Concrete Sewer Manholes by the Negative Air Pressure Vacuum Test Prior to Backfill ” vi “ Dog house ” type manholes shall not be used vii All manholes not included as part of a USACOE 404 Permit or Division 401 Certification shall maintain a separation of no less than 10 feet from wetlands G Clearing & Grubbing Clearing and grubbing , where required , shall be done prior to beginning of pipe installation It shall be done in accordance with applicable portions of items of General Conditions and the following 1 The Contractor shall consult with the Owner and Engineer prior to starting clearing and a full understanding is to be reached as to procedure The Contractor shall then conduct clearing and grubbing operations in strict accordance with these agreements a Clearing of trees and brush along the pipeline shall be carefully done so that no damage will occur outside of the limits of the right - of - way Trees and brush must be cut by hand and trees felled within the right - of - way limits All trees located within the Section 3 - 12 FORCE MAINS 2024 RevisionPage3SECTION 3 – FORCE MAINS permanent utility easement shall be cut and removed from the site Trees 6 - inches or more in diameter shall be trimmed , cut into usable lengths of 3 - feet , or as DIRECTED BY THE OWNER disposed of in a manner approved by the Engineer b Brush , laps , roots , etc , shall be disposed off - site in a manner approved by the Engineer Burning of trees , brush and debris will not be permitted , unless the appropriate permits have been obtained c Grubbing of stumps that are in the way of construction shall be done in any convenient manner , which will not cause damage to remaining trees or adjacent property Stumps shall be disposed of as brush or laps above d Limits of the pipe - laying operation shall be confined to the right - of - way and easements The width of clearing shall be held to a minimum and in no case more than the width of the easement , without the written consent of the Engineer e Easement markers shall be installed on both sides of the easement in - line with every manhole and at distances no greater than 100 - feet of all outfall lines in areas not maintained by others H Work on Highway Right - Of - Way 1 The Contractor shall not begin work on any property of the Department of Transportation until necessary right - of - way encroachment permits are in hand He shall conform to all requirements of the Department of Transportation or its authorized representatives in the prosecution of this portion of the work Prior to construction , the contractor is responsible for video taping the proposed utility route to verify pre - construction conditions It shall be the responsibility of the contractor to contact the local highway representative and to determine the exact requirements for work to be done Requirements shall include , but are not limited to the following a Where a pipeline crosses under a highway , it shall be installed by open cut , in tunnel , or in encasement under the highway Materials and method of crossing shall be indicated on the Plans for each crossing Where pipe is installed by open cut , at least one full lane for traffic shall be kept open and clear at all times The contractor shall be responsible for any certifications required for open - cut installations No joints shall be installed in uncased dry bores where dry bore is short enough to be spanned by one joint b The Contractor shall provide full - time flagmen , with appropriate stop signs , at all times when work is in progress c Necessary warning and descriptive signs shall be provided and placed at each end of the working area while work is in progress along highways These signs shall be well tended and shall be placed at sufficient distances from the site of the work so that ample warning is given to approaching traffic Signs shall be adequately lighted at night Signs should be removed , as necessary , after daily work is completed Section 3 - 13 FORCE MAINS 2024 RevisionPage4SECTION 3 – FORCE MAINS d The Contractor shall keep all streets open to traffic at all times unless permitted otherwise by County Representative or Department of Transportation as applicable The Contractor shall provide , place and maintain temporary traffic control devices as directed by the County Representative or Department of Transportation The latest edition of the Manual on Uniform Traffic Control Devices for Streets and Highways as prepared by the National Joint Committee on Uniform Traffic Control Devices shall be used as a guide in the placement of devices and all devices shall meet the requirements of said manual e Where pipe is installed in open cut across a highway , the cut shall be immediately backfilled with ABC stone and all work of repairing the pavement completed immediately Any subsequent settlement shall be immediately corrected and repaired f Where pavement is cut and replaced , the Contractor shall cut the edges to a straight and even line before repairing the pavement No ragged edges will be allowed or accepted g Where asphalt pavement or bituminous surfacing is cut , the entire area to be repaired shall be primed with an asphalt prime coat , acceptable to the Department of Transportation before the pavement is replaced h When required , the Contractor shall furnish to the Department of Transportation a 100 Performance Bond for the amount of work to be undertaken dry boring or paving to be cut and replaced along highways Bond is required in North Carolina i Unless otherwise indicated , no excavated material shall be placed on the pavement side of the ditch , along State Highways The least possible amount of trench will be left open when work is not in progress and equipment shall be removed from the pavement and shoulders during shutdown periods j Shoulders of roadways shall be left in good , acceptable condition and all topsoil and grass that is disturbed shall be replaced The Contractor shall pay the cost of all Department of Transportation inspectors time if required on the job I Work on Railroad Right - Of - Way 1 The Contractor shall not begin work on any property of the railroad until he has secured necessary permits Prior to any construction in the railroad right - of - way , the contractor shall videotape the proposed utility route in order to verify pre - existing conditions He shall conform to all requirements of the railroad , or its authorized representatives , in the prosecution of this portion of the work J Bored Encasement Installation 1 Encasement pipe which is dry bored under highways and railroads for installation of force main shall be installed at the locations , to the gradients , and within the tolerances if any , as shown on the plans In event the encasement is installed off grade or seriously out of line , then another encasement pipe will be dry bored as close as practical to the original pipe Section 3 - 14 FORCE MAINS 2024 RevisionPage5SECTION 3 – FORCE MAINS with no additional compensation allowed therefore The original encasement must be sealed with a watertight concrete plug min 3 - feet deep at each end 2 Pipelines installed through steel encasement shall meet specifications herein described and all Department of Transportation or Railroad specifications and guidelines for installing pipelines through steel encasement pipe Upon insertion of the pipeline through the encasement pipe , the ends of the encasement pipe shall be sealed with brick and mortar Brick and mortar shall be as herein specified , and the seal shall be such to withstand hydrostatic pressure from ground water and all backfill loads Contractor shall provide means to prevent water line from floating within the encasement pipe Grouting procedure will not be allowed 3 Casing pipe and joints shall be of leak proof construction , capable of withstanding railway or traffic loading The diameter of the casing pipe shall be at least 2 - inches greater than the largest outside diameter of the carrier pipe , joints , or couplings for carrier pipe less than 6 - inches in diameter and at least 4 - inches greater for carrier pipe , 6 - inches in diameter and greater , unless indicated differently on drawings Further , the casing pipe shall be of great enough diameter to allow carrier pipe to be removed subsequently without disturbing the case pipe and immediate areas 4 Steel encasement and carrier pipe shall be as specified in item 25 of this section K Trench Excavation 1 Trenches for pipe shall be dug true to line and grade and to the following requirements Depth of cover shall not be less than 3 - feet - 0 - inches for pipe up to 8 - inches in diameter and 3 - feet - 6 - inches for pipe 10 - inches and larger in diameter , measured to the top of pipe , unless shown differently on the profile or authorized by the Engineer The depth of cover shall be measured from edge of pavement or finished grade , whichever is deeper If the water main is installed in the bottom of the ditch , the depth of cover shall be measured from the bottom of the ditch 2 Sides of trenches shall be kept as nearly vertical as possible They shall be at least 12 - inches and not more than 18 - inches wider at the top of the pipe than the outside diameter of the pipe , plus sheathing where it is necessary Where paving is to be cut , it shall be cut in advance of trenching 1 - foot wider than the specified width of the trench 3 Where soil conditions prohibit vertical walls , the trench width at the bottom and at 1 - foot above the top of the pipe shall be as specified above with the remainder being held to the least possible width greater than that specified Where soil conditions prevent ditch excavation without excessive widths , or where directed by the Engineer , wood sheeting , as hereinafter specified , shall be driven to support the trench walls or a suitably reinforced steel trench box shall be employed 4 Trench bottoms shall be hand graded to provide uniform and continuous bearing for the pipe along its entire length , with bell holes being dug for pipe bells No ridges , sags , or Section 3 - 15 FORCE MAINS 2024 RevisionPage6SECTION 3 – FORCE MAINS undercutting will be allowed Excess excavating below grade shall be backfilled with suitable material which shall be thoroughly tamped 5 If approved by the Engineer and subject to suitable soil conditions , the trench may be excavated a few inches below the established subgrade and backfilled with select material from the excavation , if available well compacted and so shaped as to give the pipes uniform bearing throughout their lengths at the established grade Bell holes shall be dug to relieve the bells of load and to provide for completing the joints 6 Where the material at grade is unstable , soft , and incapable of supporting the pipe , the trench shall be excavated below grade , as directed by the Engineer , and refilled to grade with crusher - run stone or gravel to form a firm foundation for the pipe Stone shall be compacted and graded to provide a stable foundation and a uniform bearing for pipe Bell holes shall be provided as in other types of foundations 7 When authorized by the Engineer , the Contractor shall dispose of material excavated from the trench that is unsuitable for backfill material The Contractor shall provide the place select borrow material to replace unsuitable material for backfilling the trench as directed 8 Should ground water be encountered in the bottom of the trench , causing the trench bottom to be unstable , the material , as directed by the Engineer , shall be excavated below grade sufficiently to allow a bed of crushed rock or gravel to be place in which to bed the pipe The crushed rock or gravel shall be placed up to the spring line of the pipe The work shall be done as for unstable foundations The depth of cut below grade shall be only the minimum amount to accomplish the purpose , and shall be as directed by the Engineer 9 The Contractor shall furnish all machinery for pumping , bailing , and or well pointing and shall pump , bail , or otherwise remove any water which may be found or shall accumulate in the trenches , and shall perform all work necessary to keep them clear of water while the pipe is being laid The disposal of water after removal shall be satisfactory to the Engineer Well pointing must be removed upon completion of construction 10 Whenever necessary , the side of the trench shall be braced and rendered secure and either open or closed sheeting used to the satisfaction of the Engineer ; such sheeting and bracing to be left in place until the trench is refilled to a safe limit , not less than 2 - feet above the top of the pipe The top portion may then be cut off , but the lower portion shall remain undisturbed In lieu of sheeting , suitable trench boxes may be employed All sheeting , bracing , trench boxes , and trench construction methods shall conform to the latest Department of Labor Safety and Health Regulations for construction promulgated under the Occupational Safety and Health Act of 1970 11 All existing water , sewer , and gas lines , buried electrical and telephone cable , and other known utilities intersecting the lines of construction , if requested by the Engineer or County’s representative , shall be uncovered by the Contractor at his expense and exposed to the Engineer at least 100 - feet ahead of pipe laying operations of insure the correctness of grades Section 3 - 16 FORCE MAINS 2024 RevisionPage7SECTION 3 – FORCE MAINS 12 The Contractor shall at all times take necessary precautions in preventing gutters , catch basins , ditches and other drainage facilities from being clogged that might cause flooding conditions and damage to public or private properties L Rock Removal , Blasting 1 In rock or other unyielding material , the excavation shall be made at least 6 - inches below subgrade elevation The trench shall be refilled with select material compacted in place as specified for ordinary excavation Suitable material from excavation may be used , if available If not , it shall be hauled in 2 All blasting , where required , shall be done under the personal supervision of someone thoroughly skilled in this class of work All necessary measures to protect life and property shall be taken When in close proximity to buildings , transmission lines , telephone lines or other facilities , timber mats or other means of preventing damage from flying debris shall be used Ample and suitable signals shall be given in proximity to the work before each blast , and flagmen shall be placed on all roads , beyond the danger zone , in every direction to warn traffic All responsibility for damage rests on the Contractor 3 Prior to any blasting , a pre - blast survey must be conducted including an evaluation of any structures within 500 - feet of the proposed blasting The survey shall also determine well recover rates for any water supply wells within 100 - feet of the proposed blasting The Contractor shall not contact property owners directly for pre - blast surveying until the County has first provided notification to affected residents The County is not responsible for any delays associated with pre - blast surveying or notifications 4 The approved NCDOT Encroachment Agreement for the project does not allow blasting in the NCDOT right - of - way If the contractor wishes to perform blasting in the right - of - way , it shall be the responsibility of the contractor to provide any necessary information to NCDOT and acquire the revised encroachment agreement The Owner shall not be responsible for any delays associated with seeking blasting approval from NC DOT 5 Submittals required for blasting approval a Names , addresses , telephone numbers , and qualifications of the blasting subcontractor s and explosive supplier s that will be used Contact and licensing for the designated Blaster - In - Charge b Copies of certificates of completion of specialized training for the handling of explosives for the designated Blaster - In - Charge , blasting foreman and any other key personnel responsible for the work c A blasting plan , indicating the methods , materials , and equipment to be used The blasting plan shall indicate the types of explosives , drilling patterns , and general layout to be used to execute the work A licensed blaster shall select the materials and design the blasting pattern The blasting plan shall include a schedule The plan shall meet all State regulations and be sealed by a professional engineer licensed in the North Carolina Section 3 - 17 FORCE MAINS 2024 RevisionPage8SECTION 3 – FORCE MAINS d A ground vibration and air blast monitoring plan , indicating structures that will be monitored , monitoring equipment that will be used , and personnel responsible for the monitoring 6 A minimum of 24 hours prior to each round of blasting , the Contractor shall submit a detailed blast round design plan to the Engineer’s on - site representative The blasting plan submitted is for quality control and record keeping purposes Review by the Engineer shall not relieve the Contractor of his responsibilities as provided herein The blast round design submittals shall include a Location state grid coordinates and limits of the shot b Number , diameter , and depth of blast holes to be detonated in the round , and a plan showing drill hole pattern , spacing and distance to the free face c Depth of overburden d Types and total weight of the explosives to be used in the round e Loading diagram showing the location of explosives , primers , and initiators ; location , depth , and type of stemming to be used in each hole f Initiation sequence , including delay timer and delay system , total weight of explosive to be detonated on each delay , and a list of timing of delays g Manufacturer’s data sheet for all explosives , primers , and initiators used h Planned seismic monitoring positions , distances from the blast round , and seismograph types to the used to monitor vibrations and air blast overpressures i Type and amount of blasting mats and or depth of soil cover to be used over the top surface of the shot j Any other information required by applicable State and Federal regulations 7 The Contractor and subcontractor s shall comply with all applicable Federal , State , and local codes , laws , rules and regulations as well as professional society standards for the storage transportation and use of explosives 8 Blasting is subject to the following warning levels and not to exceed limits Variable Warning Level Not - to - Exceed Limit Vibration PPV gt; 40 Hz 075 in sec 19 10 in sec 25 mm sec mm sec Vibration PPV lt; 40 Hz 040 in sec 10 05 in sec 13 mm sec mm sec Air - overpressure noise 120 dBL 133 dBL 9 Post - Blast Reporting – within three 3 days of each blast , the Contractor shall submit post - blast reports including the following information at a minimum a Results and effectiveness of the blast and any proposed changes to subsequent site - specific blast plans b Blast monitoring report Section 3 - 18 FORCE MAINS 2024 RevisionPage9SECTION 3 – FORCE MAINS i Type , identification and specific location of monitoring equipment ii Distance and direction of blast iii PPV in each direction and peak vector sum iv Maximum air - overpressure c Blast damage report when necessary d Drilling records including blast pattern and blast hole drill logs 10 Rock Excavation for trenches and pits includes removal and disposal of materials and obstructions encountered that cannot be excavated with a track - mounted power excavator , equivalent to Caterpillar Model No 330 CL , and rated at not less than 247 HP flywheel and 66,094 - pound drawbar pull and equipped with a short stick and a 30 - inch - wide , tight tip radius rock bucket with rock teeth rated at 075 cubic yard heaped capacity a Typical of materials classified as rock are boulders one - half 1 2 cubic yard or more in volume , solid rock , rock in ledges , and rock - hard cementitious aggregate deposits b Intermittent drilling , blasting , or ripping performed to increase production and not necessary to permit excavation of material encountered will be classified as earth excavation c Do not perform rock excavation work until material to be excavated has been cross - sectioned and classified by the Owner’s representative , and such information provided to the Engineer for approval 11 Rock shall be defined as that solid material that cannot be excavated under the conditions stated above All blasting shall be done after coordination with the County representative and subject to all applicable regulations The County reserves the right to require the removal of rock by means other than blasting where any pipe or conduit is either too close to or so situated with respect to the blasting as to make blasting hazardous Rock taken from the ditch shall immediately be hauled away and disposed of by the contractor at his expense M Pipe Installation 1 The Contractor shall haul the pipe and appurtenances to the site of the work and distribute them neatly along the trench prior to laying The pipe shall be carefully handled to prevent damage Mechanical hoists or other approved methods shall be used in the handling Depth of cover shall not be less than 3 - feet for pipes 8 - inches in diameter and smaller , or 3 - feet - 6 - inches for pipes 10 - inches and larger in diameter , measured to the top of pipe , except where shown differently on a profile or specifically authorized by the Engineer The depth of cover shall be measured from edge of pavement or finished grade , whichever is deeper If the force main is installed in the bottom of the ditch , the depth of cover shall be measured from the bottom of the ditch 2 Pipe and appurtenances shall be kept clean and open ends securely plugged when pipe and bell and spigots shall be thoroughly inspected and cleaned prior to lowering into the Section 3 - 19 FORCE MAINS 2024 RevisionPage0SECTION 3 – FORCE MAINS ditch and care shall be exercised after the pipe is in place to prevent dirt or other extraneous material from getting into the pipe or bells and into the spigot 3 Spigots shall be fully seated in the bells and the pipe shall be uniformly bedded on the bottom of the trench for its entire length with bells lying in previously dug bell holes sufficiently large to allow proper bedding and jointing Fittings , valves , and other appurtenances shall be located where shown on the Plans or directed by the Engineer , with the pipe being cut where necessary After joining , a reasonable amount of deflection may be made in the joint Such deflection shall not exceed the allowable amount specified by the manufacturer for each size of pipe 4 PVC pipe shall be installed to all applicable portions of requirements for other pipe material and to the exact instructions of the manufacturer Adapters shall be furnished and installed as necessary when connections are made to other types of pipe 5 Fittings shall be installed where shown on the Plans or directed by the Engineer They shall be handled and installed in the same manner as the pipe and all shall be well blocked as hereinafter specified 6 HDPE pipe for directional drilling must be SDR9 or heavier and sized to have the inside diameter to match the inside diameter of the connecting force main Connection of HDPE pipe shall be installed with a fused HDPE flanged connection to FL x PE or DIP Connection details must be specifically approved by the County prior to installation 7 Fusible PVC pipe shall conform to AWWA C900 , AWWA C905 , ASTM D2241 or ASTM D1785 for standard dimensions , as applicable Testing shall be in accordance with the referenced AWWA standards for all pipe types Fusible PVC pipe shall be extruded with plain ends The ends shall be square to the pipe and free of any bevel or chamfer There shall be no bell or gasket of any kind incorporated into the pipe Fusible polyvinylchloride pipe shall be manufactured in a standard 40 - feet nominal length , or custom lengths as specified a Pipe shall be marked as follows i Nominal pipe size ii PVC iii Dimension Ratio , Standard Dimension Ratio , or Schedule iv AWWA pressure class , or standard pressure rating for non - AWWA pipe , as applicable v AWWA standard designation number , or pipe type for non - AWWA pipe , as applicable vi Extrusion production - record code vii Trademark or trade name viii Cell Classification 12454 and or PVC material code 1120 may also be included b Pipe shall be homogeneous throughout and be free of visible cracks , holes , foreign material , blisters , or other visible deleterious faults Section 3 - 20 FORCE MAINS 2024 RevisionPage1SECTION 3 – FORCE MAINS 8 No pipe joints shall be installed in uncased dry bores where dry bore is short enough to be spanned by one joint 9 Valves shall be installed at the locations shown on the Plans They shall be carefully handled , cleaned , and checked for operation prior to backfilling Care shall be taken to ensure that no dirt , rock , or other obstacles that would interfere with the valve operation are left in the valve 10 A valve box shall be installed with each underground valve They shall be carefully set , centered exactly over the operating nut and truly plumbed The base shall be set on brick , so arranged that the weight of the valve box and superimposed loads will bear on the base and not on the valve or pipe 11 Extension stems shall be furnished where depth of bury places operating not in excess of 4 - feet beneath finished grade 12 Valve markers shall be installed for each main line valve and shall be set where directed by the Engineer They shall be carefully set with the letters facing the valves and shall be plumb Distance to valve or shall be stamped on brass or bronze embed on marker N Thrust Blocking 1 Concrete for blocking and protection shall be poured in accordance with the following requirements All fittings , bends , dead ends , etc , shall be acceptably blocked with concrete having bearing on undisturbed earth in the side and or bottom of the trench Bearing area shall be equal to that shown on the Plans and greater if deemed necessary by the Engineer No concrete shall be poured or splattered on fitting bells , glands , or bolts Bags of unmixed sacrete or other bagged concrete for blocking and bracing shall not be acceptable 2 Reaction blocking for force mains 12 - inches and larger shall be transit - mixed concrete This concrete shall have a 28 - day compressive strength of 3000 psi 3 Material for reaction blocking for force mains less than 12 - inches may be composed of bagged 3,000 psi concrete that has been mixed with the correct proportion of water in accordance with the manufacturer’s recommendations O Backfilling 1 All trash , forms , debris , and other foreign material shall be cleared from around all pipes and structures before backfilling 2 Backfilling of trenches shall be completed after the installation of each section of pipe Backfilling shall be kept up with the pipe laying to the satisfaction of the Engineer 3 Backfilling around the pipe and to a depth of at least 1 - foot above the top of pipe shall be placed by hand in layers of not over 6 - inches Only select material containing no rocks or other objectionable material shall be used for this portion of the backfill As fast as the material is placed , it shall be cut under the haunches of the pipe with a shovel and thoroughly Section 3 - 21 FORCE MAINS 2024 RevisionPage2SECTION 3 – FORCE MAINS compacted with mechanical tamps for the full width of the trench to provide support for the bottom and sides of the pipe Filling shall be carried up evenly on both sides 4 The balance of the backfill shall be placed and tamped to prevent excessive settlement in a manner satisfactory to the Engineer If the trench backfill is located under miscellaneous paved areas , areas to be paved , unpaved streets , or driveways , the trench shall be backfilled with suitable material free from large stones or clods in 8 - inches layers loose measurement and thoroughly tamped and compacted to 95 of maximum as established by AASHTO Specification T99 , Method A , with mechanical tampers , so as to avoid future settlement Where applicable , the compaction shall be acceptable to the Department of Transportation or County For trenches located in streets and highways , trench backfilling shall be in accordance with the requirements of item 31 Q of this section , Cutting and Replacing Pavement 5 For pipe outside street limits , compaction shall be at least 90 of maximum as established by AASHTO Specification T99 , Method A 6 Excess material shall be promptly removed from the site , and the pavement or road surface cleaned of objectionable material Contractor shall provide screenings if trench material is placed on pavement The pavement and or road surface shall be cleaned daily with a mechanical broom and or washed if requested by the County or Department of Transportation officials 7 In unpaved streets and shoulders of roads , the top 6 - inches of trench shall be filled with well compacted topsoil In paved areas , the top of the trench shall be filled with the specified base for pavement , well mixed and compacted Any settlement of backfill below finish grade shall be promptly corrected 8 The Contractor will be responsible for all final subsidence of all trenches and shall leave the same flush with the original ground after all settlement has taken place Trenches must be protected against scour due to surface drainage The Contractor shall correct any future settlement within the guarantee period at his own expense P Dust Control 1 The Contractor shall control dust throughout the life of the project within the project area and at all other areas affected by the construction of the project Dust control shall not be considered effective where the amount of dust creates a potential or actual unsafe condition , public nuisance , or condition endangering the value , utility , or appearance of any property The Contractor will provide dust control measures as directed by the County Q Cutting and Replacement of Pavement 1 Where pavement is to be cut for installation of pipe or other utilities , the Contractor shall cut it neatly in advance of trenching and shall replace the pavement with base and new pavement Section 3 - 22 FORCE MAINS 2024 RevisionPage3SECTION 3 – FORCE MAINS 2 All pavement shall be neatly cut to a straight edge in advance of trenching with the method of cutting being subject to approval of the Engineer Pavement shall be cut 12 - inches wider than the excavated area on each side Ragged or irregular edges will not be allowed and work completed with barred edges shall be redone Concrete pavement shall be sawed with suitable concrete saw cutting equipment 3 Trench backfilling shall be done in layers not over 6 - inches thick and thoroughly compacted Compaction shall be such as to prevent future settlement and shall be done by acceptable means , approved by the County Rolling with rubber - tired vehicles or track - type equipment will not be allowed Compaction shall be at least 95 of maximum as established by AASHTO Specification T99 , Method A The entire trench shall be backfilled with crushed run stone for open cut NCDOT roads 4 Base for pavement shall be 6 - inches of HB binder and 2 - inches of I - 2 asphalt for all non - NCDOT maintained streets All base shall be placed in accordance with plan and or encroachment permit details Base width shall be shown on the plans and or encroachment permits for various types of pavement cuts 5 Crusher run stone shall be well mixed and compacted by tamping and rolling Compaction shall be to such degree as to preclude settlement Crusher run base material shall be placed at the same time that the trench is backfilled Backfilling to top of ditch , to be cut out and replaced with base material at a later date , will not be allowed 6 Crusher run base for highway pavement and adjacent drives shall be 8 - inches of stone , stabilized with 5 Portland cement It shall be thoroughly mixed prior to compacting 7 Crusher run base for non - highway pavement and drives shall be 8 - inches of stone without the addition of cement 8 Binder base for secondary roads shall be a minimum of 6 - inches HB binder conforming to specifications of the Department of Transportation 9 Concrete base shall consist of 8 - inches of concrete , r