2024 Design and Construction Standards - Section 2 - Sanitary Sewers

10 SECTION 2 – SANITARY SEWERS 1 Design 11 Minimum Design Criteria A All sanitary sewer shall be designed at a minimum in accordance with 15A NCAC 2T Regulations , “ Minimum Design Criteria for the Permitting of Gravity Sewers ” and the County Johnston County Water Distribution and Wastewater Collection , and Reclaimed Water Design and Construction Standards , whichever is more stringent B Gravity sewer lines shall be designed and laid on minimum grades per 15A NCAC 2T Regulations Maximum allowable pipe slope shall be 5 or a slope that limits flow to 15 - feet per second A minimum drop of 02 - feet shall be designed across manhole inverts C 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 D A minimum 20 - feet easement shall be provided for all sanitary sewer 0 - 15 - feet in depth A minimum 30 - feet easement shall be provided for all sanitary sewer 16 - 30 - feet in depth Johnston County shall determine minimum width of all easements for sanitary sewer deeper than 30 - feet 12 Manhole Dimensions A Manholes shall be minimum 4 - feet diameter for pipe sizes up to 18 - inch diameter , 5 - feet diameter for pipe sizes of 21 - inch to 30 - inch diameter , and 6 - feet diameter for pipe sizes of 36 - inch to 42inch diameter Where manhole depth exceeds 18 - feet , 5 - feet diameter manholes shall be used 13 Manhole Drops A Internal drops shall be required for grade changes greater than 25 - feet and for all services 25 - feet or higher above the invert of the manhole For 8 - inch internal drops , manholes must be 5 - feet diameter or larger Install a PVC tee inside drop manholes connections where they enter the manholes No more than one drop is allowed per manhole 14 Services in Manholes A Services shall tie into manholes where feasible A maximum of three services shall be allowed in a single manhole B Services must be installed with the flow of the gravity sewer C Services over 25 - feet above the invert must be installed with an inside drop with a tee where it enters the manhole 15 Manhole Spacing A Maximum spacing between manholes shall be 425 - feet unless specifically approved in writing otherwise Section 2 - 1 SANITARY SEWERS 2024 RevisionPageSECTION 2 – SANITARY SEWERS B Sewer 10 - feet or deeper within the right - of - way of new roads should be generally located in the center of the new road or outside rights - of - ways within the center of a dedicated easement 2 Materials 21 General A Pipe shall be of the type , class and diameter as hereinafter specified and called for by the Plans , Specifications and or Contract Documents Pipe shall be protective lined ductile iron , PVC composite type and or polyvinyl chloride B All PVC sewer pipe shall be bedded in stone up to the spring line For pipe depth greater than 10 - feet , sewer pipe shall be encapsulated in stone to 1 foot above pipe Trench width for 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 C Buried pipe shall be designed for laying conditions A or B for PVC pipe and laying conditions C or D for ductile iron pipe and composite pipe , see standard sewer details to withstand all internal pressures and external loads with a minimum depth to cover of 3 - feet , and greater depth of cover where required by the Plans , plus an H - 20 live load in accordance with ASSTHO specifications D Maximum depth for SDR 35 PVC shall be 14 - feet DIP , SDR 26 or AWWA C - 900 shall be allowed for depths of 14 - feet to 18 - feet DIP shall be required for all pipe at depths greater than 22 - feet The minimum class for DIP shall be Class 50 Class for DIP shall be in accordance with Ductile Iron Pipe Research Association recommendations E Pipe diameter and slope shall be consistent between manholes Material changes between manholes must be approved by the County prior to installation 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 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 Dimensions shall conform to the requirements of ANSI A216 , ANSI A218 , ANSI A2111 , and WW - P - 421 C , as applicable Dimensions shall be gauged at sufficiently frequent intervals to assure dimensional control Insides of sockets and outside of spigot ends shall be tested with circular gages D Wall thickness shall be determined for the design depth of cover shown in accordance with ANSI A2150 - 1976 Minimum allowable wall thickness shall be Class 50 E All pipes shall be tested at the factory in accordance with ANSI requirements for each Section 2 - 2 SANITARY SEWERS 2024 RevisionPageSECTION 2 – SANITARY SEWERS type F Each pipe shall be coated on the outside with standard bituminous coating of either coal - tar or asphalt base approximately one mil thick The coating shall be continuous , smooth , and strongly adherent to the pipe and shall not become brittle from cold or sticky from heat 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 equal Pipe must be marked on the outside indicating the interior coating Pipe without these markings shall be rejected G 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 23 Polyvinyl Chloride PVC Gravity Sewer Pipe A PVC gravity sewer pipe shall be type PSM conforming to ASTM D3034 , SDR - 35 , SDR - 26 or AWWA C - 900 , with bell and spigot rubber O - ring gasketed joints The standard length of pipe shall be 125 - feet ± 1 inch All fittings and accessories shall have bell and spigot configurations identical to pipe B 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 C 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 Service Lines A Service lines shall be polyvinyl chloride PVC and meet the material requirements as specified above in section 23 PVC service pipe shall have a minimum wall thickness of 0125 - inch and shall conform to ASTM D3034 - 78a Where services are greater than 14 - feet deep , service must match the material of the main line B A grease trap must be installed on the premises prior to setting the water meter for any food service establishments An oil separator must be on the premises prior to setting the water meter for any automotive service establishment C Service lines shall be installed so that the service line is not exposed no aerial sewer services D Service lines shall be installed on sewer lines adjacent to the front or rear property lines Connections to sewer lines on side lot lines will not be allowed E Services shall tie into manholes where feasible A maximum of three services shall be allowed in a single manhole Section 2 - 3 SANITARY SEWERS 2024 RevisionPageSECTION 2 – SANITARY SEWERS F When services are designed inline on new pipelines , service shall be installed as in - line PVC wyes on PVC lines and epoxy coated wyes on ductile iron pipes G Saddles shall not create an intrusion into the interior profile of the existing pipe Ductile iron saddles shall be Sealtite Tee by General Engineering Co , or equal PVC saddles 25 Tees , Wyes , and Miscellaneous Fittings A Fittings for service connections on new main lines shall be the same material as the main and shall conform to the above applicable specifications Mechanical wyes shall be DIP with interior coating Protecto 401 or Sewper Coat on DIP sewer mains Cleanout risers shall be installed plumb Risers shall be flush with grade with a cast iron valve box No fabricated fittings allowed B Transition couplings may be used to join ductile iron with PVC sewer pipe when a change in pipeline material is required in between manholes as long as the transition does not intrude into the profile of the interior of the pipe Transition couplings shall be ductile iron , deep bell , push on type Material shall comply with ASTM A536 All couplings shall have pipe stops and a flow way tapered to allow a smooth transition between pipes Transitions shall must be preapproved by County 26 Manhole Material A Manhole material shall be precast concrete All materials shall be approved by the County prior to use All manholes requiring an inside drop connection will be a minimum of 5 - feet in diameter B Precast concrete manholes shall consist of precast reinforced concrete sections , a conical or flat top section as required , and a base section conforming in general to the details shown on the plans Precast manhole sections shall be manufactured in accordance with ASTM Specification C478 The minimum compressive strength of the concrete for all sections shall be 4,000 psi The maximum allowable absorption of the concrete shall not exceed 8 percent of the dry weight C The manhole shall have a flexible coupling cast into the manhole making it an integral part of the manhole at each inlet and outlet hole This coupling shall be rigid , secure and provide water tightness yet provide flexibility at the pipeline to manhole connection D Manhole joints shall be sealed with preformed elastomer gasket material Also , manhole joints shall be grouted on the interior and exterior with cement 27 Drop Manholes A PVC or FRP pre - fabricated drops shall be PVC pipe with tee at the inside drop manholes B Interior piping for drop manholes shall be secured with type 316 SS expansion anchors Pipe supports shall be placed no more than 18 - inch apart C All drop manhole designs shall be approved by the County prior to installation Section 2 - 4 SANITARY SEWERS 2024 RevisionPagePage pageNumber5SECTION 2 – SANITARY SEWERS D Schedule 80 PVC pipe material shall be used inside the manhole , but the transition to schedule 80 must be made outside the manhole with approved transition couplings E The interior of manholes receiving an inside drop over 30 - inch shall be coated with at least 50 mils surface dry epoxy sealer prime and finish coating approved by the County Shop drawings material specifications of coating must be supplied to the County for approval All concrete shall cure at least 30 days prior to applying coating 28 Casting and Steps A Cast iron frame and cover shall be provided with each manhole Castings shall meet ASTM A - 48 and shall have an asphalt coated finish Manhole steps shall also be provided for manholes over 4 - feet deep Steps shall consist of ½ - inch grade 60 steel coated with copolymer polypropylene plastic conforming to ASTM D4101 and ASTM A615 Step spacing shall be consistent with the latest OSHA requirements B Manhole covers , frames , and steps shall conform to the details for each type manhole on the plans , or to similar plans differing in detail but of equally good design , provided such castings are approved by the County prior to use Covers and frames shall be machined to provide plane , smooth surfaces for uniform seating and interchangeability of covers Rings and covers that provide imperfect seating will be rejected All covers and frames shall be suitable for traffic service Minimum opening shall be 22 - inch in diameter , minimum weight of cover shall be 120 lbs , and minimum weight of frame shall be 190 lbs Manhole covers shall have no holes unless located on a sanitary sewer outfall above grade and outside the right - of - way Special frames and covers shall be provided where manholes are installed within traffic areas and for sealing manholes watertight at locations shown on the plans These frames and covers shall conform to the above specifications and shall be provided with a one - piece rubber gasket seated into the manhole frame In floodplains , water tight lids with gaskets and bolt down hardware must be provided Manhole rings should be bolted to the concrete and sealed with mastick no grout allowed 29 Concrete A Concrete for piers , protection , and other uses shall be composed of Portland cement , sand , coarse aggregate , water and such admixtures as may be allowed in such proportions as to provide a minimum 28 - day compressive strength of 3,000 psi The source of concrete and mix design shall be approved by the Engineer prior to use 28 - day compression tests are required for pier construction 210 Crushed Stone A Crushed stone for pipe bedding shall conform to ASTM C33 , size no 67 with a size range of ½ - inch to one inch Section 2 - 5 SANITARY SEWERS 2024 RevisionPagePage pageNumber6SECTION 2 – SANITARY SEWERS 211 Steel Encasement Pipe A All gravity sewer lines crossing roadways shall be installed as carrier pipe in encasement pipe B Encasement pipe for installation under highways and railroads shall be spiral welded steel pipe conforming to ASTM Specification A252 - 61 , Grade 2 Encasement pipe shall conform to DOT 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 C Carrier Pipe shall be same as pipe material on line segment PVC pipe shall be installed with locking gaskets through the carrier pipe D Spacers – Stainless steel “ spiders ” shall be provided At least 2 spacers per joint shall be provided for ductile iron pipe and 4 spacers per joint shall be provided for PVC pipe 3 Installation , Inspections and Tests 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 , permits , or other legalities are in order He shall familiarize himself with all conditions and or limitations of such rights - of - way or permits and shall fully comply with all such requirements All work shall be confined to rights - of - way or permit limits and any encroachment beyond such limits shall be the Contractors liability B Relation of Sewer to Water Bodies 1 Horizontal Location a Sewers located along streams , lakes or impoundments , shall be located at least 10 - feet outside of the stream bank unless subject to B 2 of this section or sufficiently removed from the bank to provide for future possible stream widening and to prevent siltation of the stream during construction b A distance of 50 - feet shall be maintained between sewers and water for water classified WS except WS - I or WS - V , B , SA , ORW , HQW , or SB from normal high water or tide elevation and wetlands c If the 50 ft separation cannot be maintained , manhole must meet the following criteria 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 Section 2 - 6 SANITARY SEWERS 2024 RevisionPagePage pageNumber7SECTION 2 – SANITARY SEWERS 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 2 Cover Depth a The top of all sewers entering or crossing streams shall be at a sufficient depth below the natural bottom of the stream bed to protect the sewer line The following cover requirements shall be met i 1 - foot of cover where the sewer is located in rock ii Three feet of cover in other material unless ferrous pipe is specified In major streams , more than three feet of cover may be required ; and iii In paved stream channels , the top of the sewer line should be placed below the bottom of the channel pavement C Relation of Sewers to Water Mains 1 Water mains shall be laid at least 10 - feet laterally from existing or proposed sewers , 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 over 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 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 2 The following minimum separations shall be provided for the sewer system except as Section 2 - 7 SANITARY SEWERS 2024 RevisionPagePage pageNumber8SECTION 2 – SANITARY SEWERS allowed by Paragraph g of this Rule a 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 Alternatives where separations in Paragraph f of this Rule cannot be achieved c For all other separations , materials , testing methods and acceptability standards meeting water main standards 15A NCAC 18C shall be specified 3 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 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 for 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 4 With regards to manholes a Manholes shall be provided with a watertight frame and cover with gasket b All manhole seams shall be externally taped sealed c Manholes shall be provided with a full waterproof interior coating lining d Watertight pipe connections shall be provided consisting of a flexible rubber boot or compression type connector e 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 ” f “ Dog house ” type manholes shall not be used g 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 E Clearing & Grubbing Section 2 - 8 SANITARY SEWERS 2024 RevisionPagePage pageNumber9SECTION 2 – SANITARY SEWERS 1 Clearing and grubbing , where required , shall be done prior to beginning of pipe installation Contractor shall obtain erosion control permit before beginning any work 2 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 3 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 Alternating trees and brush may be cut and mulched with approved equipment with debris mulch uniformly distributed within the easement Trees 6 - inches or more in diameter shall be trimmed , cut into usable lengths of 3 - feet , or as DIRECTED BY THE OWNER and the logs neatly stacked on the edge of the right - of - way or disposed in a manner approved by the Engineer 4 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 5 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 as for brush or laps above 6 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 All trees within a sewer outfall easement shall be removed 7 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 F Work on Highway Right - of - Way 1 The contractor shall not begin work on any property of the Department of Transportation until necessary 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 each Bidder 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 2 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 as 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 3 The Contractor shall provide full - time flagmen , with appropriate stop signs , at all times Section 2 - 9 SANITARY SEWERS 2024 RevisionPage0SECTION 2 – SANITARY SEWERS when work is in progress 4 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 5 The Contractor shall keep all streets open to traffic at all times unless permitted otherwise by the Engineer or Department of Transportation as applicable The Contractor shall provide , place and maintain temporary traffic control devices as directed by the Engineer 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 6 Where pipe is installed in open cut across a highway , the cut shall be immediately backfilled and all work of repairing the pavement completed immediately Any subsequent settlement shall be immediately corrected and repaired 7 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 8 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 9 When required , the Contractor shall furnish to the Department of Transportation a 100 Performance Bond for the amount of paving to be cut and replaced along highways Bond is required in North Carolina 10 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 11 Shoulders of roadways shall be left in good , acceptable condition and all topsoil and grass that is disturbed shall be replaced Grassing shall include seeding fertilizing , and mulching to conform with the Department of Transportation requirements The Contractor shall pay the cost of all Department of Transportation inspectors time , if required on the job G 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 Section 2 - 10 SANITARY SEWERS 2024 RevisionPage1SECTION 2 – SANITARY SEWERS H Bored Encasement Installation 1 Encasement pipe which is dry bored under highways and railroads for installation of water lines 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 The original encasement must be sealed with a watertight concrete plug min 3 - feet deep at each end 2 In event an obstruction is encountered during encasement boring operations which cannot be overcome , a second encasement shall be bored at a location designated by the Engineer In event an obstruction is encountered in the second installation , at the direction of the Engineer , a third attempt shall be made to complete the encasement installation All abandoned encasement pipes shall be sealed as specified in paragraph 3161 above 3 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 4 Casing pipe and joints shall be of leakproof construction , capable of withstanding railway or traffic loading The diameter of the casing pipe shall be at least 2 - inch greater than the largest outside diameter of the carrier pipe , joints , or couplings for carrier pipe less than 6 - inch in diameter and at least 4 - inch greater for carrier pipe , 6 - inch 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 5 Steel encasement and carrier pipe shall be as specified in item 211 of this section or by the railway owner , whichever is greater I Trench Excavation 1 Trench excavation shall be made along the lines designated by the Engineer and to the depth necessary for laying the sewer to the required grade 2 Sides of trenches shall be kept as nearly vertical as is allowable by the Occupational Safety and Health Administration They shall be at least 12 - inch and not more than 24 - inch wider at the top of the pipe than the outside diameter of the pipe plus sheathing where it is necessary Where pavement is to be cut It shall be cut in advance of trenching 1 - foot wider than the required width of the trench Section 2 - 11 SANITARY SEWERS 2024 RevisionPage2SECTION 2 – SANITARY SEWERS 3 Where soil conditions prohibit vertical walls , the trench width at the bottom and to 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 or steel 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 undercutting will be allowed Excess excavating below grade shall be backfilled with suitable material which shall be thoroughly stamped 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 selected 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 crushed stone or gravel to form a 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 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 Well pointing must be removed upon completion of construction 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 10 Whenever necessary , the side of the trench shall be braced and rendered secure and either open or close sheathing used to the satisfaction of the Engineer ; such sheathing 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 be then 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 Section 2 - 12 SANITARY SEWERS 2024 RevisionPage3SECTION 2 – SANITARY SEWERS 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 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 J Rock Removal , Blasting 1 In rock or other unyielding material , the excavation shall be made at least 6 - inch 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 Section 2 - 13 SANITARY SEWERS 2024 RevisionPage4SECTION 2 – SANITARY SEWERS 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 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 mm sec 10 in sec 25 mm sec Vibration PPV lt; 40 Hz 040 in sec 10 mm sec 05 in sec 13 mm sec Air - overpressure noise 120 dBL 133 dBL Section 2 - 14 SANITARY SEWERS 2024 RevisionPage5SECTION 2 – SANITARY SEWERS 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 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 11 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 12 Intermittent drilling , blasting , or ripping performed to increase production and not necessary to permit excavation of material encountered will be classified as earth excavation 13 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 14 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 K Pipe Installation 1 Ductile Iron Pipe a Ductile iron pipe in trench shall be laid as shown in the Standard Sewer Details Pipe Laying Conditions B and C Joints in cast iron sewers in trench shall be completed with rubber gaskets in accordance with Federal Specification WW - P - 421b Each pipe shall be coated on the outside with standard bituminous coating of either coal - tar or asphalt base approximately one mil thick The coating shall be continuous , smooth , and strongly adherent to the pipe and shall not become brittle from cold or sticky from heat Pipe shall be coated on the interior with Sewper Coat as manufactured by Lafarge Section 2 - 15 SANITARY SEWERS 2024 RevisionPage6SECTION 2 – SANITARY SEWERS Calcium Aluminate or Protecto 401 ceramic lining as manufactured by US Pipe , or equal Pipe must be marked on the outside indicating the interior coating Pipe without these markings shall be rejected 2 PVC Gravity Sewer Pipe a PVC gravity sewer pipe shall be type PSM conforming to ASTM D3034 , SDR - 35 , SDR - 26 , or AWWA C - 900 with bell and spigot rubber O - ring gasketed joints PVC pipe I trench shall be laid as shown in the Standard Sewer Details Pipe Laying Conditions A and B b All sanitary sewer pipe for pipe sizes up to 24 - inch in diameter shall be assembled by using a bar and wood block to push the pipe into the home position The wood block shall be placed across the end of the pipe to act as a fulcrum point and protect the joint end during assembly When absolutely necessary , the sanitary sewer pipe may be assembled by using the excavating equipment to apply pressure when pushing the pipe into the home position When this method is used , a wood block shall be provided at the end of the pipe for protection of the end joint , and the pipe shall be held in a horizontal position with a sling and perfectly aligned with the preceding joints before assembly The Contractor shall have the approval of the Engineer before assembling sanitary sewer pipe using the excavating equipment as a means of pushing the pipe into the home position Notwithstanding the Engineers approval , the Contractor shall be liable for any damage to the pipe as a result of using the excavation equipment Pipe which is not true to alignment , or which shows settlement after laying , shall be taken up and relayed 3 Pipe on Piers a Standard installation shall be of an “ H ” Pile configuration with concrete footings and piers only allowed upon County approval i The County must inspect the soil conditions prior to pouring concrete and reserves the right to require a 3rd party geotechnical evaluation of the soil condition compatibility b Carrier pipe shall be AWWA C900 pipe with bell restraints within a spiral wound steel encasement c Spacers – Stainless steel “ spiders ” shall be provided At least 4 spacers per joint shall be provided for PVC pipe 4 Connecting to Existing Sewers a Where shown on plans or directed by the Engineer , new sewers shall be connected to existing sewers by constructing a manhole or by cutting through the wall of an existing manhole Connections to the County’s manholes and pump - station wet - wells shall be cored with a booted connection A representative of the County must witness connections to any part of the sewer system ; otherwise , the County will not accept the new installation After construction of the new manhole , the old sewer shall be broken Section 2 - 16 SANITARY SEWERS 2024 RevisionPage7SECTION 2 – SANITARY SEWERS out and the inverts properly formed For an existing manhole an opening shall be completely filled around the pipe with cement mortar and brick so as to be watertight A channel shall then be formed over the manhole floor , or the floor cut through and the channel formed in it , as may be required by the grade L Manholes 1 “ Doghouse ” manholes shall not be used 2 Manholes shall be constructed in accordance with details on the Plans and shall be of true dimension and form They shall be so constructed as to exclude all ground water 3 The following manholes must be epoxy coated on the interior a Manholes receiving a force main and the next manhole downstream b Manholes with drops greater than 2 ½ - feet c Manholes in or within 10 - feet of wetland areas and all manholes within 50 - feet of a waterbody 4 The interior coating of manholes shall be at least 125 mils surface dry epoxy sealer prime and finish coating approved by the County In each case the system approved is listed by the epoxy product listed The contractor shall use the manufacture’s recommended system and method of surface preparation and base coating specific to the material selected to ensure proper bonding and meet the one 1 year workmanship bond adherence warranty Pre - approved systems for all depths include Sewer Guard TG , Spectrashield , Raven 405 , Perpetucoat , Sherwin Williams Dura - Plate 6100 , Permaform Cor - Roc and EpoxyTec CPP For application in manholes 15 feet in depth or less approved systems also include Standard Cement Materials , Inc 4553 Epoxy , Dinjer SG Mastic , Cor - guard 301 and Tnemec Series 434 Perma - Shield FR a Alternate products must be preapproved by the County Shop drawings material specifications of coating must be supplied to the County for approval b Interior coating shall include the entire bench area and channel , side walls and cone to the lid ring frame providing an adequate seal on all pipe inlets and outlets c Material Specifications i Product Type Polyurethane or solid epoxy ii Compressive Strength 12,000 psi for manholes 0 - 15 feet in iii Depth ; 15,000 psi for manholes greater than 15 feet in depth iv Tensile Strength 1,500 psi v Hardness Type D 60 vi Bond Strength concrete gt; Tensile strength of concrete d Coating systems must be applied by a Certified Applicator of the coating manufacture with a minimum of 200 hours field experience and according to the manufacturer specifications e Coating systems shall have a one 1 year manufacturer warranty and a one 1 Section 2 - 17 SANITARY SEWERS 2024 RevisionPage8SECTION 2 – SANITARY SEWERS year workmanship including bond adherence warranty 5 Precast Manholes - Precast manholes shall be constructed as follows a Precast base sections shall be installed on stabilized foundation so prepared to prevent settlement and misalignment Pipe openings shall be exactly aligned to that of the pipe entering and leaving the manhole b Rubber ring joints or semi - rigid composition joints shall be carefully made in accordance with the manufacturers instructions and generally in the following manner Bells shall be wiped clean , be free of all dirt or other matter , and liberally lubricated for receiving the spigot ends The gasket groove and gasket shall be well cleaned and lubricated prior to placing c Cement mortar joints shall be carefully made to the manufacturers requirements Grout shall be as stiff as possible to be consistent with good practice and all joints shall be well filled d Sewer pipe shall be placed in the openings provided in the base section and properly aligned and set to grade They shall be firmly held in place by the flexible coupling and the base opening shall be filled with an expanding type grout well rammed into place e Steps shall be properly placed at 16 - inch intervals f Cast iron frames and covers shall be properly secured to top of manhole using a minimum of 4 ea ½ - inch expanding stainless steel anchor bolts and gaskets in non - traffic areas and on raised manholes Internal joint seals shall be used to secure the frame to the manhole in traffic areas 6 Manhole Tops Manhole tops shall be set to the proper elevation as dictated by the location , or as directed by the Engineer Care shall be exercised to set the tops at the proper elevation Where manholes are located in streets or roads , the tops shall be set to conform to the finished grade of the roadway Tops of manholes located in yards , roadway shoulders or populated areas shall be set flush with the ground elevation , unless directed otherwise by the Engineer Manhole tops set flush with ground elevation shall have no holes In cultivated fields , wooded areas and along outfall sewers the manhole tops shall be set approximately 2 - feet 1 - foot for residential lots above the elevation of the ground unless the line is subject to flooding or other hazards In such instances , manhole tops shall be set to the elevations given by the Engineer Vents shall be installed on selected manholes , as specified on the plans M 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 above the top of pipe shall be Section 2 - 18 SANITARY SEWERS 2024 RevisionPage9SECTION 2 – SANITARY SEWERS placed by hand in layers of not over 6 - inch 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 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 , or unpaved streets , the trench shall be backfilled with suitable material free from large stones or clods in 8 - inch 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 Owner For trenches located in streets and highways trench backfilling shall be in accordance with the requirements of item 31 O 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 The pavement and or road surface shall be cleaned daily with a mechanical broom and or washed if requested by the Engineer The Contractor shall correct any future settlement within the guarantee period 7 In unpaved streets and shoulders the top 6 - inches of trench shall be filled with well compacted crusher - run stone 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 On outfall lines and at other points where damage to the system or property will not occur , the backfill material more than 1 above the top of the pipe may be placed in 12 - inch layers and compacted with mechanical tamps The upper portion of the backfill , more than 5 - feet above the pipe may be compacted by rolling with wheeled equipment Excess material may be mounded on the trench 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 9 Backfilling around manholes shall , in general , conform to requirements for backfilling trenches , except that no backfill shall be placed around manholes until all mortar has properly set , and backfilling shall be carried up symmetrically around structures N 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 , Section 2 - 19 SANITARY SEWERS 2024 RevisionPage0SECTION 2 – SANITARY SEWERS public nuisance , or condition endangering the value , utility , or appearance of any property The Contractor will not be directly compensated for any dust control measures necessary , as this work will be considered incidental to the work covered by the various contract items The Contractor will provide dust control measures as directed by the County O Cutting and Replacement of Pavement 1 Where pavement is to be cut for installation of pipe or other utilities , the Contractor shall cut it nearly in advance of trenching and shall replace the pavement with base and new pavement 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 - inch wider than the excavated area on each side Ragged and irregular edges will not be allowed and work completed with ragged 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 - inch thick and thoroughly compacted Compaction shall be such as to prevent future settlement and shall be done by acceptable means , approved by the Engineer 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 4 Base for pavement for all non - NCDOT maintained streets shall be 6 - inch of HB binder and 2 - inch of I - 2 asphalt All base shall be placed in accordance with plan and or encroachment permit details Base width shall be as 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 - inch 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 - inch of stone without the addition of cement 8 Binder base for secondary roads shall be a minimum of 6 - inch HB binder conforming to specifications of the Department of Transportation 9 Concrete base shall consist of 8 - inch of concrete , reinforced with # 4 reinforcing steel bars placed at 8 - inch on center in the transverse direction # 4 tie bars in the longitudinal direction Concrete shall be designed to produce a compressive strength of 3,000 psi at 28 days The design of the mix and source of supply shall be subject to approval of the Engineer 10 All pavement shall be repaired within the same week that it is cut Should inclement weather delay pavement replacement , the Contractor shall not cut additional pavement until Section 2 - 20 SANITARY SEWERS 2024 RevisionPage1SECTION 2 – SANITARY SEWERS he has notified the Engineer and received specific permission and instructions If the Contractor fails to make repairs within the same week , the County reserves the right to hire an outside contractor to make such repairs and bill the Owner Contractor for the work performed 11 For asphalt pavement or bituminous surfacing , the entire area to be resurfaced including edges of existing pavement shall be primed with an acceptable asphalt prime coat just prior to placing new pavement P Removal and Replacement of Driveway , Sidewalk , Other Items 1 Where pipe is to be placed under existing concrete driveway or sidewalk , the concrete shall be removed in construction units unless their length is more than 10 - feet , in which case the concrete shall be cut as specified in paragraph 31 O of this section The backfill shall be thoroughly compacted for the entire depth of the trench 2 The driveway shall be replaced with 3,000 psi concrete , 6 - inch thick ; sidewalks shall be 3,000 psi concrete , 4 thick The concrete shall be placed monolithic and dressed off with a wooden float , brush and edging tool Where pipe is to be placed under concrete driveway or walk , the Contractor may , with the permission of the Engineer , install the pipe by tunneling instead of removing and replacing the driveway or walk If pipe is to be placed under curb and gutter , it shall be done by tunneling 3 The Contractor shall be responsible for removing and replacing items such as mail boxes , fences , shrubbery , walls , steps , and any other private ornamental items that are in direct conflict with the water line work All items shall be replaced within the same day that it is removed , unless otherwise approved by the County If the Contractor fails to replace items within the same day , the County may hire an outside Contractor to make such repairs and bill the Owner Contractor for the repair work performed Q Piers and Protection Work 1 Protection concrete shall be poured in such locations as shown on the plans or directed by the Engineer It shall consist of one - part Portland Cement , two parts sand and four parts crushed stone 2 The end of openings between the encasement and carrier pipes shall be sealed with clay or concrete bricks and low strength mortar R Miscellaneous Items 1 The Contractor shall be responsible for removing and replacing miscellaneous items in conflict with the sewer line work such as mail boxes , signs , fences , walls , shrubbery , private ornamental items , etc Shrubbery and plantings shall be preserved by proper root protection and watering until replanted Tree limbs shall be protected where possible Damaged trees shall be repaired with an approved tree dressing Section 2 - 21 SANITARY SEWERS 2024 RevisionPage2SECTION 2 – SANITARY SEWERS S Repairs to Damaged Services and Utilities 1 Repairs to damaged services and utilities shall be promptly made at the Contractors expense The Contractor shall use every effort to avoid damaging or breaking water , sewer , gas , power , telephone or other utility services Utility lines shall be properly supported across the pipe trench until backfilling is completed Should damage occur , immediate action shall be initiated to effect satisfactory repairs All repair work shall be satisfactory to the Engineer and owner of the damaged utility T Cleanup 1 All pipeline rights - of - way and pipework areas shall be cleaned up and left in satisfactory condition 2 Cleanup of work along highways or roads shall be made immediately upon completion of the backfill operation Ditching and pipe laying shall be stopped at any time that cleanup work lags and shall not be resumed until cleanup progress is satisfactory to the Engineer Final cleanup and condition of the work area shall be subject to the approval of the State Highway Representative , the Owner , the County , and the Engineer 3 Cleanup of work for cross - country locations shall follow immediately upon the completion of any major part of the work or upon instructions by the Engineer Topsoil shall be replaced on all areas disturbed by the pipeline work throughout the length of the sewer main , and to the full satisfaction of the property owner Topsoil may be removed from the line of work and stockpiled for future use It shall be carefully removed , stockpiled , protected , respread , dressed off , and the entire right - of - way left in condition acceptable to the Engineer and property owner If topsoil is not stockpiled and protected , suitable , approved material from other sources shall be provided Where the line is located on pasture land , grassed areas , or roadway shoulders , grass shall be replaced 4 All disturbed pipeline area shall be seeded in accordance with NC DOT Standards 32 Testing A Vacuum Testing 1 Vacuum testing for gravity sewer within streets will be done after the stone base or asphalt has been completed 2 Prior to testing , all lifting holes shall be plugged with non - shrink grout and all manhole tops shall be bolted to the cone section using concrete expansion anchors and sealed down with asphaltic cement or “ ram - neck ” In doing the vacuum test , all pipes entering the manhole shall be plugged and secured from being drawn into the sewer line Inflate the compressor band to affect a seal between the vacuum base and the manhole cone section Connect the vacuum pump to the outlet port with the valve open A vacuum of ten inches 10 - inch of mercury shall be drawn and the vacuum shut off with the valves closed , the time Section 2 - 22 SANITARY SEWERS 2024 RevisionPage3SECTION 2 – SANITARY SEWERS for the vacuum to drop to nine inches 9 - inch of mercury shall not be less than the following table Manhole Depth 48 ” Dia 60 ” Dia 72 ” Dia 0 - 10 - feet 60 sec 75 sec 90 sec 10 - 15 - feet 75 sec 90 sec 105 sec 15 - feet - Greater 90 sec 105 sec 120 sec 3 If the manhole fails , repairs wi