3-Technical Specifications.pdf

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1. EXCAVATION, TRENCHING AND BACKFILLING…

2. TP 11 INDIVIDUAL SEPTIC TANK

3. TP 12 INDIVIDUAL LIFT STATION

4. TP LOW PRESSURE-DOSED GRAVEL DRAINFIELDS

*SEE DESIGN ATTACHMENT FOR ADVANCED TREATMENT UNIT

SPECIFICATIONS

TABLE OF CONTENTS

1/06 Technical Provisions- TP 3.0 Excavation, Trenching, and Backfilling

3.01 Scope of Work

The work covered by this section includes the furnishing of all plant, labor, tools, equipment, and material, and performing all operations in connection with the excavation, trenching, and backfilling for the installation of all pipelines, structures, and accessories, all in accordance with these technical provisions and applicable drawings.

3.02 Protection of Excavation

In conformance with applicable safety regulations, the Contractor shall provide suitable shoring and sheeting to protect all excavations and provide safe working conditions for workers.

3.03 Excavation

3.03.01 General

All excavation required for the performance of this contract shall be made by open cut methods unless otherwise shown on the drawings, required by applicable encroachment permits, or approved in writing by the Project Manager.

3.03.02 Trench Excavation

The sides of all trenches for the installation of utility piping systems shall be as nearly vertical as soil conditions permit below the level of the top of the pipe. The width of the trench shall not be less than 12-inches or more than 24-inches wider than the outside diameter of the pipe barrel. Trench excavation shall be centered on pipe alignment such that a minimum clear space of 6-inches is provided on each side of the pipe. Trench width above the level of the top of the pipe may be as wide as necessary for shoring and sheeting, and for proper installation of the work.

The depth of all trenches shall be as indicated on the drawings. If not otherwise specified, the depth of all trenches shall be sufficient to provide a minimum cover of 24- inches at all locations after final backfilling.

Unless otherwise required by applicable permits to be less, the maximum length of trench that may be left open at any one time shall not exceed 500-feet. No trenches shall be left open unless otherwise permitted in writing by the Project Manager.

All trench excavation shall comply with Federal and local OSHA regulations for trench safety.

TECHNICAL PROVISION 3.0

EXCAVATION, TRENCHING AND BACKFILLING

3.03.03 Pavement Cutting

Where it is necessary to remove sections of asphalt pavement, the asphalt shall be saw-cut with approved equipment in a neat line 6-inches back from the outside edge of the excavation in order to provide a key when restored, or as approved by BIA roads permit or Tribal Manager.

Where it is necessary to remove sections of concrete pavement, the concrete shall be saw-cut to a depth of not less than 2-inches with neat, vertical, true lines in such a manner that the adjoining surface will not be damaged.

3.04 Placement and Compaction of Pipe Embedment and Backfill Material

3.04.01 Pipe Embedment

Pipe embedment is defined as that material required to bring the trench bottom up to grade and that material placed alongside and above pipe to a level of at least 6 inches over the top of the pipe. The pipe embedment area is divided into three zones as defined below.

Bedding: Bedding is that portion of pipe embedment zone beneath the pipe. If the native soil is suitable for bedding the pipe without over- excavation, the bottom of the trench shall be accurately shaped such that one fourth of the pipe circumference is provided with uniform bearing and support for each section of the entire length of the pipe. Imported bedding material shall likewise be placed to provide uniform and adequate longitudinal support under the pipe. Bedding material shall be placed and compacted in lifts not to exceed 6-inches in loose measure.

Haunching: Haunching is that portion of the pipe embedment zone from the bottom of the pipe to the springline of pipe. Haunching material shall be placed and consolidated to provide adequate side support to the pipe while avoiding both vertical and lateral displacement of the pipe from proper alignment.

Initial Backfill: Initial backfill is that portion of the pipe embedment zone from the springline of the pipe to a minimum level of 6-inches over the top of the pipe. Initial backfill material shall be placed and compacted in lifts not to exceed 6 inches in loose measure. Compaction shall be performed in a manner to avoid damage and disturbance of the embedded pipe.

3.04.02 Compaction

Unless otherwise specified by applicable permits or roadway authority, bedding, haunching, initial backfill, final backfill, and gravel resurfacing shall be compacted to the following percent of the maximum density as determined by ASTM D1557. In-place densities of materials shall be determined by the sand-cone method, ASTM D1556 or by nuclear methods, ASTM D2922.

Percent of Maximum Density

Location Bedding Haunching Initial Backfill

Final Backfill

Roadways and Driveways 95% 95% 95% 95%

Unimproved Surfaces, Fields, Etc.

90%

90%

70%

70%

3.05 Surface Restoration and Resurfacing

3.05.01 General

The inclusion of a bid item and estimated quantity for asphaltic, concrete, or gravel resurfacing in the Bid Schedule indicates that these items are probable. However, the exclusion of these items from the Bid Schedule does not preclude the possibility that they will be required, merely that they are not anticipated. If unanticipated resurfacing is required, unit prices will be negotiated between the Contractor and the Contracting Officer.

3.05.02 Surface Restoration

After the piping and structures have been installed and all backfilling has been completed, areas which were disturbed shall be brought to true grades. All slopes shall be trimmed and dressed, and all surfaces graded to maintain existing drainage. All streets, alleys, driveways, sidewalks, curbs, or other surfaces which have been disturbed or damaged shall be resurfaced with like materials to a condition equal to or better than the original condition. All excess excavated material shall be properly disposed of by the Contractor.

3.05.03 Asphaltic Resurfacing

At all locations where asphaltic resurfacing is required, a compacted gravel base, 6-inches in depth shall be placed prior to placement of the asphaltic wear course. This base course shall be 95 to 100 percent 3-inch minus gravel with not more than 40 percent passing a

0.0165 inch square opening (No. 40 sieve). Asphalt shall be plant mixed, with certification that the mix meets the requirements of the applicable roadway authority. Except where greater thickness is required by applicable roadway authority, the minimum thickness of the asphalt shall be the greater of 2-inches or that of the existing adjacent asphalt.

Placement of asphalt shall be in lifts not exceeding 2-inches. Compaction shall be accomplished by pneumatic-tired or steel rollers throughout the spreading operation. Final rolling shall be by steel roller. No surfacing shall be placed while the subgrade is wet, if it is raining, or if the temperature is below 40 degrees F. All edges shall be clean and tack coated prior to placement of the patch.

3.05.04 Gravel Resurfacing

All gravel resurfacing shall be done on a properly compacted subgrade. The gravel shall be spread uniformly and compacted to a minimum thickness of 3-inches. The gravel shall conform to the following gradation requirement.

Sieve Size Percent Passing Square Opening By Weight

3/4 inch 100

0.250 inch (No. 3 sieve) 50-65

0.0029 inch (No. 200 sieve)

5 max.

3.06 Open Cut Road Crossing for Water and Sewer Service Lines

Open cut water and sewer service line crossings shall be completed at all locations shown on the site plan. The Contractor is responsible to comply with all local, county, Tribal and BIA road crossing provisions whether a permit was issued or not. PVC encasement pipe shall be the diameter shown on the drawings and shall conform to material specification ASTM D1784, Type 1, Grade 1, manufacturing specification ASTM D2241, and the pipe shall be PVC schedule 80. All PVC pipe joints shall be rubber compression ring type with rubber gaskets conforming ASTM F477, and equal to J-M Ring Tite PVC Pressure Rated Pipe, or PWPipe TwinSeal PVC.

Steel encasement pipe and fittings shall be the diameter shown on the drawings and shall be Schedule 40 and shall conform to ASTM A120. The pipe shall be joined by the use of threaded steel couplings

3.07 Bored Type Road Crossing for Water and Sewer Service Lines

Water service lines crossing roads or rights-of-way (ROWs) which cannot be open cut, and if noted on the site plan, the crossing shall be bored. The Contractor shall bore the crossing by using a pneumatic or hydraulic boring machine such as a Hole Hog®, or other approved boring equipment. Minimum allowable encasement pipe diameter for the crossing shall be of sufficient size to allow the water or sewer service line to be easily slid into position.

Casing pipe diameter and material shall be approved by the Project Manager prior to installation.

1/06 Technical Provisions TP 11.0 Individual Septic Tank

11.01 Scope of Work

and material, and performing all operations in connection with the construction of individual septic tanks, including connection to building (house) drains, solid sewer pipe, cleanouts, abandonment of existing septic tanks, fittings, effluent filters, and appurtenances in accordance with these technical provisions and applicable drawings.

11.02 Permits and Approvals

The Government shall secure the applicable site approvals and sewage disposal permits for the work specified herein.

11.03 Location of Facilities

The location of the facilities specified herein shall be as shown on the drawings and/or as staked in the field by the Project Manager. The Contractor shall not change the designated location of these facilities without the prior approval of the Project Manager.

11.04 Inspection of Installation

In addition to the applicable inspection requirements of the Tribe and/or County, the Contractor shall notify the Project Manager at least 2 working days prior to placing final backfill over the septic tank so that the Project Manager may inspect the installation.

11.05 Solid Sewer Pipe

The Contractor shall install a solid smooth pipe from the septic tank to the building (house) drain. Solid sewer pipe and fittings shall be 4-inch PVC plastic, ASTM 3034, SDR 35 sewer service lines. Installation shall be in accordance with all state and local and/or Tribal standards.

11.06 Effluent Filter

The Contractor shall install in the outlet tee of the septic tank a 1/16th-inch effluent filter cartridge equivalent to Orenco Biotube Residential Septic Tank Effluent Filter or Tuf-Tite EF- 4 Residential Series. The outlet tee in the septic tank shall be of sufficient length to extend one (1) inch below the bottom of the filter cartridge (See detail drawings)

TECHNICAL PROVISION 11.0

INDIVIDUAL SEPTIC TANK

11.07 Septic Tank

11.07.01 Tank

The tank shall be precast, reinforced, watertight concrete as manufactured by an established firm specializing in concrete products conforming to ASTM 6913. Minimum liquid capacity below the outlet level shall be as specified on the drawing(s) and each tank shall have 2 compartments. The walls, floor & top shall have a minimum thickness of 2 ½-inches. Adequate steel reinforcement shall be provided. Each compartment shall be provided with adequate tees, elbows and baffles. The tank shall meet all state and local standards.

11.07.02 Access Riser

Each compartment of the septic tank shall be provided with a watertight access riser with a minimum dimension of 24-inches for inspection and sludge removal. The access riser on the second chamber shall be centered so as to provide access to the effluent filter.

Access risers shall meet all state and local standards. Additional access ports, if required by local health codes, shall be installed by the Contractor at no additional expense to the Government. Risers shall be equal to Orenco systems lids and risers.

11.07.03 Septic Tank Installation

The septic tank shall be set in a hole excavated by the Contractor in accordance with all state and local standards.

11.07.04 Traffic Rated Tank

Where septic tanks are installed beneath driveways, parking areas, roadways, or other areas subject to vehicular traffic, the septic tank, access risers, lids, and all associated structural components shall be designed, manufactured, and certified to withstand AASHTO H-20 (HS-20) traffic loading, or greater.

The septic tank shall comply with ASTM C1227, Standard Specification for Precast Concrete Septic Tanks, and all applicable federal, state, and local regulations. The tank shall be designed with minimum wall and floor thicknesses of 5 inches and a minimum top slab thickness of 6 inches, unless greater thickness is required by the manufacturer's structural design.

The tank shall be constructed of reinforced concrete with a minimum compressive strength of 4,000 psi at 28 days and shall include sufficient reinforcing steel to safely resist all design loads. Reinforcing steel shall conform to ASTM A615, Grade 60, or ASTM A1064 for welded wire reinforcement, as applicable.

Each tank compartment shall be provided with properly sized inlet and outlet tees, elbows, and baffles as required for the intended service and applicable regulations.

Access risers shall be constructed of reinforced concrete or manufacturer-certified traffic-rated HDPE or polypropylene composite materials. Access lids shall be reinforced concrete, ductile iron, or manufacturer-certified composite traffic-rated assemblies. The complete riser and lid assembly shall be designed for the required traffic loading and shall be watertight, gas-tight, and securely fastened with corrosion-resistant hardware.

Joints between precast concrete tank sections and risers shall be sealed with preformed butyl rubber sealant conforming to ASTM C990, or approved elastomeric gaskets specifically designed for wastewater applications. Lid and riser gaskets shall be manufactured from EPDM or neoprene elastomeric rubber, or approved equal, and shall provide a durable watertight and gas-tight seal.

The completed installation shall safely withstand the anticipated vehicular loading without structural failure, excessive deflection, settlement, cracking that compromises structural performance, or loss of watertight or gas-tight integrity.

11.08 Pump Existing Septic Tank

When included on the bid schedule, the Contractor shall pump existing septic tanks by pumping the liquid and solids out of the tank. The septic tank liquid and solids shall be disposed of as required by local health codes. Backfilling pumped liquid to agitate the accumulated solids in the septic tank is not allowed.

11.09 Abandon Existing Septic Tank

When included on the bid schedule, The Contractor shall abandon existing septic tanks by pumping out the liquid out of the tank, breaking open the cover of the tank, and backfilling the empty tank with approved borrow material. Backfilling shall be carefully placed to eliminate voids, and shall be mounted to allow for settlement. The septic tank liquid shall be disposed of as required by local health codes.

11.10 Underground Cleanout

Where required and as shown on the plans, the Contractor shall install a two-way underground cleanout on the solid sewer line. The cleanout shall have a threaded plug and be constructed as detailed in the drawings. The cleanout shall be extended so that the square nut on the threaded plug is ½-inch below finished ground level. If indicated on the plans, a concrete pad 18-inches square and 4-inches deep shall be poured around each cleanout at the ground surface. This pad shall be reinforced with welded wire mesh with a minimum 1 1/2-inch concrete cover over mesh. The wire mesh shall be ASTM approved W1.4 (1/8-inch) wire mesh on 6-inch centers.

1/06 Technical Provisions TP 12.0 Individual Lift Station

12.01 Scope of Work

and materials, and performing all operations in connection with the construction of an individual lift station, including lift station basin, effluent pump, piping, force main, fittings, control panel, electrical controls and alarms, and appurtenances in accordance with these technical provisions and applicable drawings.

12.02 Lift Station

The lift station basin shall be either the second chamber of a septic tank, as shown in the drawings, or a precast, reinforced, watertight concrete basin as manufactured by an established firm specializing in concrete products, and shall conform to ASTM C1227. The basin shall have a minimum wall thickness of 2½-inches and the concrete shall obtain a minimum 28-day compressive strength of 3,000 psi.

The basin shall be as specified on the drawing(s), including the required minimum volume.

The lift station basin shall be provided with a watertight access riser with a minimum diameter of 24-inches for inspection and maintenance. The access riser shall meet all state and local standards.

If indicated on the plans, an 18-inch square pedestal 4-inches high shall be provided as a base for the pump. The pedestal shall be located as shown on the drawing.

The installation of the lift station basin shall conform to the provisions of TP 11.0 for the installation of the septic tank and meet all state and local standards.

Lift station basins installed beneath driveways, parking areas, roadways, or other areas subject to vehicular traffic, the septic tank, access risers, lids, and all associated structural components shall be designed, manufactured, and certified to withstand AASHTO H-20 (HS-20) traffic loading, or greater. The installation of the traffic rated lift station basin shall conform to the provisions of TP 11.07.04.

12.03 Effluent Pump

The sewage pump shall be as specified on the drawing(s), 230/240 volt, single phase submersible effluent pump. The pump shall be capable of passing 3/8-inch solids and running

TECHNICAL PROVISION 12.0

INDIVIDUAL LIFT STATION

at the flow rate and total dynamic head as specified in the design. Differing site conditions may require a similar pump with minor differences in flow/head characteristics to be provided by the Project Manager. The pump power cord shall be easily detachable from motor housing.

Connector shall be sealed to motor housing with rubber O-ring. The pump details shall be as shown on the drawings or equal. If specified in the design, the effluent pump shall be installed within an Orenco Systems or equivalent effluent filter vault. If installed in the septic tank, the vault shall be installed with the inlet holes of the vault not less than 31-inches from the floor of the septic tank.

12.04 Electrical Controls and Alarm

The Contractor shall furnish and install a control system compatible with the supplied pump.

The controls shall include; circuit breakers for the pump and alarm system, magnetic contactor, mercury level control floats, a high liquid level alarm, running and alarm lights, and a Hand- Off-Automatic selector switch. All wiring shall be in accordance with the National Electrical Code and applicable state and local electrical codes. The installation shall be inspected and approved by the State Electrical Inspector.

Electrical service to the lift station shall be either from a new properly sized circuit breaker in the existing circuit breaker panel servicing the home, if space permits, or through a separate subpanel. Separate circuit breakers are required for both the pump magnetic contactor and for the alarm system. In any case a fused disconnect is required if service entrance panel or sub-panel is greater than 50 feet from the lift station and/or not in clear sight of the lift station and shall be located as shown on the drawings or as directed by the Project Manager.

The control panel shall be a NEMA 4X enclosure and shall house the "Hand-Off-Automatic" switch, green "pump on" indicator light, a terminal block for connecting the mercury float level controls, and the alarm system. The green "pump on" light, red alarm light and silence button shall be mounted through the enclosure door.

The magnetic contactor, alarm system, and control panel shall be mounted on outside wall of the home at a location acceptable to the homeowner. As an alternative, and with the approval of the Project Manager, the control panel or alarm panel may be located on a post near the lift station as long as the components are housed in NEMA 4X enclosure.

The pump electrical cable shall be Type UF single conductor cable sized to limit the overall voltage drop from the service entrance to the pump motor to less than 2 percent. In no case, shall wires smaller than 12 gauge be used. The electrical cable and control wires shall be buried at least 18 inches deep. House interior wiring shall be 12 gauge minimum and shall be Type NM or UF cable, while required conduit shall be EMT, PVC, or liquid tight flexible metal. All supports, nails, bolts, straps and screws shall be galvanized. The submersible power cable from the pump and the float cables shall be secured to a hook and secured such that the cables are not allowed to slip from their adjusted height.

The mercury level control switches shall be completely encapsulated in polyurethane foam and equipped with cord weights. The float switch shall be installed at the elevations indicated or as otherwise directed by the Project Manager. The electrical cable housing from the switches to the control panel shall be Type UF 14 gauge copper single conductor cable. Splices shall be made by using mechanical connectors and covering with heat-shrink tubing.

12.05 Control System Functional Requirements

12.05.01 Demand Dosing

The liquid level in the individual lift station is sensed by three mercury level control switches suspended at different elevations from the top of the lift station. The first (lowest) mercury level control switch shall be a redundant off switch and shall de-energize the pump should the middle dual action on-off float fail. The middle float shall be dual action and energizes and de-energizes the lift station pump. The third (highest) mercury level control switch energizes the red light and alarm bell indicating a high water level condition.

During the normal mode of operation, the HAND-OFF-AUTOMATIC switch shall be in the "Automatic" position. As the liquid level in the individual lift station reaches energize level of the middle dual action mercury level control switch, an electrical signal shall be transmitted through the buried electrical cable to the control panel. The controls shall energize the lift station pump and green running light. As the liquid level in the individual lift station drops to the middle de-energize level, an electrical signal shall be transmitted to the control panel which shall de-energize the lift station pump and green running light.

This cycle shall continue to repeat itself. Should the middle dual action on-off float fail, the redundant lowest level float shall de-energize the pump and activate the alarm bell and red alarm light indicating a low level float failure.

If the liquid level in the individual lift station rises to the top mercury level control switch, the red light and alarm bell shall be energized indicating a high liquid level condition. The alarm shall be silenced by manually pushing the "Alarm Silence" button, however, the red pilot light shall remain energized until the liquid level has fallen below the third mercury level control switch. This high liquid level light and alarm shall operate independently of the position of the pump selector switch.

When the pump selector switch is in the "Hand" position, the mercury level float switches shall be overridden and the lift station pump and green running light shall be energized independently of the liquid level in the lift station. When the pump selector switch is in the "Off" position, there shall be no power provided to the lift station pump and green running light.

12.05.02 Timed Dosing

Timed dosing may control the liquid level in the individual lift station, if specified by the Project Manager and shown on the drawings, with three mercury level control switches.

The third (highest) mercury level control switch serves as a high water level alarm and energizes the red light and alarm bell indicating a pump failure condition. When the pump is operational and dosing overload occurs, the liquid level will reach the second (mid-level) mercury level control switch and the timer shall be overridden, energizing the lift station pump and the green pump running light on the control panel. As the liquid level drops, reaching the first (lowest) mercury level, the control switch overrides the timer and de-energizes the lift station pump and the green running light.

When the liquid level in the individual lift station does rise to the third (highest) mercury level control switch, the alarm shall be silenced by manually pushing the “Alarm Silence” button. However, the red pilot light shall remain energized until the liquid level has fallen below the second mercury level control switch. This high liquid level light and alarm shall operate independently of the position of the pump selector switch.

When the pump selector switch is in the “Hand” position, the timer and mercury level float switches shall be overridden and the lift station pump and green running light shall be energized independently of the liquid level in the lift station. When the pump selector switch is in the “Off” position, there shall be no power provided to the lift station pump and green light running.

12.06 Piping

12.06.01 Lift Station Influent and Pump Discharge

The piping from the septic tank outlet to the lift station inlet shall conform to TP 11.0, solid sewer pipe. The inlet shall include a tee or baffle, as specified. The outlet discharge from the pump shall be Schedule 40 PVC 1120 pipe installed as shown in the drawings and to the approval of the Project Manager. Fittings shall be Schedule 40, ASTM 2466, except for the union, which shall be Schedule 80. The union shall be installed within easy reach from the manhole cover, hand-tight only. The male adapter that screws into the discharge port of the pump shall not be glued in place; standard plumbers’ pipe joint compound shall be used.

12.07 Force Main

12.07.01 Pipe and Fittings

The effluent force main pipe from the lift station to the shallow drainfield shall be the size shown on the drawings, PVC 1120, conforming to ASTM 2241. All fittings for the pipe shall be 160 psi PVC with rubber compression ring joints or schedule 40 PVC with solvent welded joints.

The force main pipe shall be laid on grade in a trench at least 12-inches wide. Care shall be taken to bed the pipe in a material that is free of rocks or otherwise unsuitable material.

Backfill shall be compacted by hand from the bottom of the trench to a minimum of 6-inches over the top of the pipe for the full width of the trench. A minimum of 18-inches of cover is required over the top of the pipe.

12.07.02 Distribution Valves

If indicated on the drawings, mechanical distribution valves (Orenco or approved equal) shall be installed on the transport line between the pump and discharge laterals.

The mechanical distribution valve shall be sized to match the number of distribution zones in the treatment area. Valves shall be installed per the manufacturer’s instructions, with particular regard given to the elevation placement of the valves on the pressurized transport line.

If the final distribution elevation is more than 2 feet above the elevation of the distribution valves and the system does not drain back into the dosing tank, check valves should be installed immediately downstream from the valves, and a pressure release should be installed immediately upstream of the valves.

12.08 Submittals

The Contractor shall submit for approval prior to construction product/material information on the sewage lift station pump and controls.

1/06 Technical Provisions TP 14.0 Low-Pressure-Dosed Gravel Drainfields Page 13

TECHNICAL PROVISION 14.0

LOW PRESSURE-DOSED GRAVEL DRAINFIELDS

14.01 Scope of Work

The work covered by this section consists of furnishing all labor, tools, equipment, and materials in connection with the construction and installation of a low pressure drainfield absorption system, in accordance with applicable technical provisions and drawings.

14.02 Site Preparation

Prior to installation, the Contractor shall remove all ground vegetation, stumps, and other extraneous material from the construction area of the drainfield, as shown on the drawings, dispose of it in a manner approved by the Project Manager. The Contractor shall, as best as possible, maintain the drainfield’s undisturbed natural soil structure. Excess excavated soil, if any, shall be removed from the construction site or stockpiled in an area on the property as directed by the Project Manager. In order to install the facilities specified herein at the optimum grade and elevation, the Contractor is required to utilize an accurate builder's level and rod, or approved equal, during construction. The level shall be mounted on a tripod and shall be on site at all times during installation

14.03 Piping

14.03.01 Transport and Manifold Pipe

The transport and manifold pipes shall be Schedule 40 PVC pipe, PVC 1120, conforming to ASTM 1785, at the diameter as defined in the Bid Schedule and drawings. Fittings shall be Schedule 40, conforming to ASTM 2466. If specified in the drawings, adjustable ball valves shall be installed on the feeder pipes to each lateral.

14.03.02 Distribution Laterals

The distribution laterals shall be at the diameter as specified on the drawing(s) and shall be Schedule 40 ASTM 1785 pipe, PVC 1120. Field perforations (orifices) shall be at the diameter as specified in the drawings, spaced as shown in drawings, oriented in the 12 o'clock position, except that the last hole in each lateral shall be drilled so that the hole is pointing down (the 6 o'clock position).

Fittings shall be Schedule 40, ASTM 2466. The ends of the laterals shall be fitted with a male adapter and cap, screwed on hand-tight. Teflon tape shall be used. All fittings, except as specified shall be glued in place. All joints shall be primed before gluing.

14.03.03 Observation Pipe

Observation pipes shall be installed at locations shown in the drawings. Observation pipes shall be 4-inch diameter perforated PVC drainfield pipe fitted with a secure screw cap. At least one pipe shall be wrapped with filter fabric all the way from the ground surface to the bottom, and shall be installed so that it extends to the bottom of the sand layer. At least one pipe shall be wrapped from

1/06 Technical Provisions TP 14.0 Low-Pressure-Dosed Gravel Drainfields Page 14 ground surface down to the top of the gravel layer, and installed so that it extends to the bottom of the gravel layer. All pipes shall extend at least 6-inches above the trench surface.

14.04 Solvent Cement

All fittings, except as specified shall be glued in place. Solvent cement shall meet ASTM D2564.

Laterals shall not be glued to the manifold until after the pressure test. Pipe shall be cut square and deburred inside and out. All joints shall be primed before gluing.

14.05 Gravel

The gravel shall be clean, hard, strong, non-deteriorating stone, free from coal, clay, soft fragments, or other deleterious materials, and may vary in size within the diameter range specified on the drawings, with not more than ten (10) percent fines below the ½-inch size. Gravel shall be considered clean if water poured through it remains clear. The top of the gravel shall be covered with a polyester polymer plastic filter drainage fabric having a nominal weight of 5-ounces per square yard. Gravel to be used must be approved by Project Manager.

14.06 Low Pressure Drainfield

14.06.01 Installation

The shallow pressurized drainfield shall be located as shown on the drawings. The Contractor shall excavate to the length, depth, and in the direction shown in the drawings. All compacted surfaces of the trench shall be raked to expose the natural texture of the soil. All loose material shall be removed from the trench. If unanticipated conditions are encountered in the field which will adversely affect the performance of the drainfield (clay, bedrock, hard pan, groundwater, etc.), the Project Manager shall be notified immediately. Open trenches shall be protected from surface runoff by diversion ditches or other methods.

The distribution laterals shall be pressure tested before covered and all clogged holes cleared. All shallow pressurized drainfield trenches shall be a minimum of 36-inches wide or as shown on the drawings. The bottom of the trench shall be laid level to within plus or minus 0.1 feet. The drainfield trench shall be carefully backfilled in a manner that will not damage the distribution laterals. Excavation in excess of backfill requirements shall be spread over the drainfield area.

Gravel shall extend below and over the top of the drainfield distribution lateral pipe to the depths shown on the drawings. The drainfield gravel shall be placed carefully to avoid damage to the soil.

14.07 Low Pressure Sand Lined Drainfield

14.07.01 Materials

14.07.01.1 Medium Sand Fill

The medium sand fill material shall meet the following particle size gradation (Source:

ASTM C-33, Specification for Fine Aggregate):

1/06 Technical Provisions TP 17.0 Pressure-Dosed Chamber and At-Grade Drainfields

Effective % Passing

Sieve Particle Size by Weight

3/8 inch 9.50mm 100% No. 4 4.75mm 95-100% No. 8 2.36mm 80-100% No. 16 1.18mm 50-85% No. 30 0.60mm 25-60% No. 50 0.30mm 5-30% No. 100 0.15mm 0-10%

The sand shall be not more than 45% passing any one sieve and retained on the next consecutive sieve of those shown above.

The fineness modulus shall not be less than 2.3 nor more than 3.1. The fineness modulus is defined as the sum of the cumulative percentages retained in the sieve analysis, divided by 100, for the sieve sizes shown above. Each load of fill sand shall be approved by the Project Manager.

14.07.02 Installation

The Contractor shall excavate a bed with a width and length as shown on the drawing(s), to the depth specified. The medium sand fill shall be placed as shown in the drawings with a minimum depth of 24-inches except for where the gravel shall be placed, where the depth shall be at least 15-inches.

Then the gravel bed with a minimum overall depth of 10-inches shall be installed in the area cut out of the sand. The gravel bed must be laid level in the bed cut into the top of the sand fill. The bottom of the bed shall be level within ± ½-inch. A minimum of 6-inches of gravel shall be placed below the distribution laterals and a minimum of three 3-inches of gravel shall be placed over the laterals.

Install the two observation pipes, ensuring that they are secured in place during the rest of the installation.

The distribution laterals shall be placed on the first layer of gravel. The manifold to the force main shall be connected from the pump chamber. The laterals shall be laid level, removing any large rises and dips. Pressure test the distribution system for uniformity of flow. All clogged orifices shall be cleared; all soil and other obstructions shall be removed from the laterals. Glue the laterals to the manifold. Orifices shall be oriented in the 12 o'clock position, except that the last hole in each lateral shall be drilled so that the hole is pointing down (the 6 o'clock position).

Place 3 inches of gravel over the laterals to fill the bed. The top of the gravel bed shall be covered with filter fabric equal to Type 3401, overlapping the edge of the bed by at lest 6-inches. The gravel bed shall have a minimum 12-inch cover of sandy loam on top of the gravel trench. Place topsoil over the backfill material and seed the topsoil. Alternatively, the Contractor may sod the site.

14.08 Site Restoration, Grading and Ditching

The Contractor will be held responsible for repairing trench settlement problems during the one-year warranty period. Excess excavated soil shall be distributed evenly around the site and all soil shall be seeded. The Contractor shall provide grading and/or ditching around the completed drainfield to direct the flow of surface runoff away from the drainfield. The exact location of the ditch lines will be determined by the Project Manager after the drainfield installation is completed.

1/06 Technical Provisions TP 17.0 Pressure-Dosed Chamber and At-Grade Drainfields

14.09 Submittals

The contractor shall submit all product/material information. The Contractor shall also submit after construction an as-built drawing of the co