Chapter 18.24 SANITARY SEWERS

All sewers shall be designed and constructed so as to conform to the requirements of the Oregon State Department of Environmental Quality, the Oregon Standard Specifications for Construction, and the city of St. Helens. Public sewerage facilities shall be designed to allow the logical service of all parcels or tracts of land within the basin being considered. Sewer lines shall be extended to adjacent parcels to best facilitate future development. The extension of the public sanitary sewer systems to serve any parcel or tract of land shall be done by and at the expense of the property owner or developer. (Ord. 2875 Appx. § 510, 2003)

18.24.010 Scheduling.

(1) Sequence of Operations. The contractor shall plan and execute construction work to cause a minimum of interference to the operation of existing city facilities. It may be necessary to do certain parts of the construction work outside normal working hours in order to avoid undesirable conditions, and it shall be the obligation of the contractor to make this change to the work schedule. This scheduling, however, is subject to city approval, and does not relieve the contractor from making its work available for inspection.

(a) Connection to Existing System. When installing a new manhole to make a connection to an existing system, the existing main line shall be diverted around the new structure until all testing of the new pipe and manhole(s) has been completed. This can be accomplished by installing a section of temporary pipe and 45 degree bends around the new manhole and backfilling until testing is completed to the city’s satisfaction.

Connections between existing work and new work shall not be made until necessary inspections and tests have been completed on the new work and it is found to conform in all respects to the requirements of the plans and specifications.

(2) Progress of Construction. Construction shall proceed in a systematic manner that will result in minimum inconvenience to the public. Construction staking for the work being performed shall be completed prior to the start of excavation. The contractor shall limit its operations to a small length of work area per crew. At no time shall the trenching equipment be farther than 300 feet ahead of the pipe laying crews, unless advance written permission is given by the city. The trench shall be backfilled so that no section of trench is left open longer than 24 hours. Trenches located in a right-of-way shall be completely backfilled before the contractor leaves the site for the day unless the trench is adequately secured with steel plates.

Cleanup of all construction debris, excess excavation, excess materials, and complete restoration of all fences, mailboxes, ditches, culverts, signposts, and similar items shall be completed immediately following the final backfilling of the trench.

Any area disturbed by the contractor’s operations inside dedicated easements shall be restored to its original condition. Any area that is disturbed by the contractor’s operations outside the dedicated easement shall be restored to the property owner’s satisfaction. (Ord. 2875 Appx. § 510.1, 2003)

18.24.020 Preservation, restoration, and cleanup.

(1) Site Restoration and Cleanup. The contractor shall keep the premises clean and orderly at all times during the job and leave the project free of rubbish or excess materials of any kind upon completion of the work. During construction, the contractor shall stockpile the excavated trench materials so as to do the least damage to adjacent lawns, grassed areas, gardens, shrubbery, trees, or fences, regardless of the ownership of these areas. All excavated materials shall be removed from these areas, and these surfaces shall be left in a condition equivalent to their original condition and free from rock, gravel, boulders, or other foreign material. Stockpiles shall be removed or tarped during wet weather conditions throughout the entire construction process. The contractor shall replace topsoil areas over all trenches with a minimum finished depth of 12 inches of topsoil. All existing drainage ditches and culverts shall be reopened and graded, and original drainage restored. All damaged irrigation and house drainage pipe, drain tiles, sanitary sewer or storm laterals, and culverts shall be repaired expeditiously. The finished surface shall conform to the original surface and shall be free-draining, free from holes, rough spots, or other surface features detrimental to a seeded area.

(2) Preservation of Irrigation and Drainage Ditches. Following the backfill of the trenches, the contractor shall restore all public and private irrigation and storm drain ditches that have been destroyed, damaged, or otherwise modified during construction to the condition of the ditch before construction. Ditches shall be built in their original locations unless otherwise redesigned as part of the project.

(3) Stream and Creek Crossings. The contractor shall comply with all provisions of the permits required by the Oregon Division of State Lands, the U.S. Army Corps of Engineers, Oregon Department of Environmental Quality, Department of Fish and Wildlife, Columbia County, and any other agencies having jurisdiction. (Ord. 2875 Appx. § 510.2, 2003)

18.24.030 Interferences and obstructions.

(1) General. Various obstructions may be encountered during the course of the work. Maps and information regarding underground utilities shall be obtained from the utility owning and operating such utilities, but the location of such utilities is not guaranteed. At least two but not more than 10 business days shall be given to the Oregon Utility Notification Center prior to commencement of the construction operation. The contractor shall comply with the Oregon “locate law,” ORS 757.557. If services of any utility are interrupted due to the construction operation, the proper authority shall be notified immediately.

(2) Protection. The contractor shall exercise all due care in protecting property along the route of the improvement. This protection shall include, but not be limited to, trees, yards, fences, drainage lines, mailboxes, driveways, shrubs, and lawns. If any of the above have been disturbed, they shall be restored to as near their original condition as possible. (Ord. 3186 § 24, 2015; Ord. 2875 Appx. § 510.3, 2003)

18.24.040 Permanent survey monuments.

The contractor shall not disturb permanent survey monuments, property corners, stakes, or benchmarks without prior written consent of the appropriate county surveyor. It shall be the responsibility of the contractor to protect such survey markers. Survey markers that are disturbed or lost shall be replaced by a registered land surveyor. When a change is made in the finished elevation of the pavement, or any roadway in which a permanent survey monument is located, the monument cover shall be adjusted to the new grade. (Ord. 2875 Appx. § 510.4, 2003)

Article II. Trench Excavation and Backfill

18.24.050 Materials.

(1) Pipe Bedding. Pipe bedding material shall be clean crushed rock with a maximum size of three-fourths inches, uniformly graded from coarse to fine or as approved by the city.

(2) Trench Backfill. Above the pipe zone will be divided into the following classifications:

(a) Class A Backfill. Class A backfill shall be native or common material, which in the opinion of the city meets the desired characteristics required for the specific surface loading.

(b) Class B Backfill. Class B backfill shall be three-fourths-inch to zero-inch granular grade of crushed rock material, unless otherwise approved. Class B backfill will be required in all public rights-of-way. (Ord. 2875 Appx. § 520.1, 2003)

18.24.060 Construction.

(1) Excavation.

(a) Clearing the Right-of-Way. Clearing shall be completed prior to the start of trenching. The contractor shall observe all federal, state, and local laws relating to fire permits, burning materials, and other requirements. Under no condition shall brush be covered by excavated materials prior to being cleared and removed.

Excavated material shall be placed at locations and in such a manner that it does not create a hazard to pedestrian or vehicular traffic, nor interfere with the function of existing drainage facilities. During wet weather conditions, stockpiles shall be removed or tarped throughout the construction process.

(b) Open Trench Limit. The length of the open trench shall always be kept to a minimum. The city shall determine the amount of the open trench allowed based upon work conditions of the area. In normal cases, the open trench length shall not exceed 300 feet.

(c) Trench Width. The trench width at the surface of the ground shall be kept to a minimum necessary to install the pipe in a safe manner. In all cases, trenches must be of sufficient width to allow for shoring, proper joining of the pipe, and backfilling of material along the sides of the pipe. The minimum trench width in the pipe zone must provide a clear working space of six inches outside the maximum outside diameter of the pipe.

Excavation for manholes and other structures shall be wide enough to provide a minimum of 12 inches between the structure’s surface and the sides of the excavation.

(2) Installation.

(a) Shoring. The contractor shall provide all materials, labor, and equipment necessary to adequately shore trenches to protect the work, existing property, utilities, pavement, etc., and to provide safe working conditions, in compliance with all OSHA requirements. (Ord. 2875 Appx. § 520.2, 2003)

Article III. Pavement Restoration

18.24.070 General.

The stricter of the requirements of this article or the standards of the jurisdiction having authority over the road being repaired shall be followed.

If an existing street that is classified as a collector or an arterial has been paved within five years or any other classification of street has been paved within three years, the trench patch shall be made with a “T” cut and will be fog sealed from the lip of gutter to lip of gutter or flow line to flow line to ensure that the structural integrity of the existing street is maintained. The street shall be milled if necessary to maintain proper crown. (Ord. 2875 Appx. § 530.1, 2003)

18.24.080 Materials.

(1) Crushed Rock. The following rock specifications shall be required unless modified by the local jurisdiction:

(a) Base course rock for the street shall be one and one-half inches and shall conform to the applicable portions of the “Standard Specifications for Highway Construction” of the Oregon Department of Transportation for course aggregate base material.

(b) Rock for the leveling course shall be three-fourths-inch minus, conforming to the applicable portions of the “Standard Specifications for Highway Construction” of the Oregon Department of Transportation for leveling course.

(2) Asphalt Concrete.

(a) Material for prime coat shall be emulsified asphalt-type CMS-2 or approved equal.

(b) Materials for tack coat shall be emulsified asphalt-type RS-1, CRS-1, or approved equal.

(c) When more than three inches of asphalt concrete is required, the asphalt concrete shall be placed in two or more courses. The base course may be Class B asphaltic concrete mix conforming to the “Standard Specifications for Highway Construction” of the Oregon Department of Transportation in lieu of Class C mix.

(d) Asphaltic concrete for the surface course shall be Class C mix conforming to the Standard Specification of the Oregon Department of Transportation. All surface course mix design is subject to final approval by the city.

(e) If multiple lifts are used, the base course shall be a minimum thickness of two inches, and the wearing course shall be Class C OSHD mix with a minimum thickness of one and one-half inches. (Ord. 2875 Appx. § 530.2, 2003)

18.24.090 Workmanship.

(1) Subgrade. The contractor shall:

(a) Bring the trench to a smooth, even grade at the correct distance below the top of the existing pavement surface, allowing for base rock, leveling rock and asphalt concrete.

(b) Trim existing pavement so that the trench width plus 12 inches of asphalt is removed creating a “T” cut section as shown in the standard drawings.

(c) Remove any pavement that has been damaged or that is broken and unsound and provide a smooth, neat cut with a sound edge for joining the new pavement.

(d) Compact the top four feet of pavement subgrade to 95 percent relative density, ASTM D2049.

(e) Accomplish supplementary compaction where required with approved mechanical vibrating or power tampers.

(2) Base Aggregate Course and Leveling Course. The contractor shall obtain certification of the subgrade material prior to placing any base course material on the subgrade.

(3) Tack Coat. After the leveling course has been compacted, the contractor shall apply the tack coat to the edges of all surfaces being paved at a rate of 0.06 to 0.12 gallons per square yard. The surface upon which the tack coat is applied shall be dry and clean of dirt, dust, and other matter inhibiting asphalt adherence.

(4) Weather Conditions. Asphaltic concrete placement shall conform to Part 700 of the Oregon Standard Specifications for Construction and in no instance shall be placed when the surface temperature is lower than 40 degrees Fahrenheit, during rainfall, or when the surface is frozen or wet.

(5) Protection of Structures. The contractor shall provide whatever protective coverings may be necessary to protect the exposed portions of bridges, culverts, curbs, gutters, posts, guard fences, road signs, and any other structures from the paving operations. All oil, asphalt, dirt, or other undesirable matter that may come upon these structures by reason of the paving operations shall be removed.

Existing and new water valve boxes, manholes, catch basins, or other underground utility appurtenances shall be made level with the finish asphalt grade. The city or other appropriate authority shall be contacted prior to any facility adjustments for guidance as to the appropriate procedures, standards and materials to be used. All covers shall be protected during asphalt application.

Existing monuments shall have paving rings for monument boxes placed over each monument to allow for ease of future access as shown in the standard details. The contractor shall be responsible for all costs associated with this work.

(6) Rock Surfacing. Where so directed by the city, the contractor shall place a minimum of two inches of level course rock, as specified in this chapter, for the full width of all streets, driveways, parking areas, street shoulders, and other areas disturbed by the construction.

(7) Contractor’s Responsibility. The contractor shall repair all settlement of pavement over trenches within the warranty period at no charge to the city.

(8) Driveways. Driveways shall be replaced to original conditions following the work. Such replacement shall be done in accordance with all applicable legal standards for road shoulders within the limits of the work.

Existing drainage patterns shall not be altered unless approved by the city engineer to correct a drainage problem. (Ord. 2875 Appx. § 530.3, 2003)

Article IV. Engineering

18.24.100 Sewage flows.

The Manning’s coefficient value (“n”) to be used in calculating sewage flows is 0.013. Sewers of sizes that are obviously larger than are necessary for satisfactory carrying capacity, but that are specified in order to meet grade requirements, are not allowed. (Ord. 2875 Appx. § 540.1, 2003)

18.24.110 Pipe design.

No public sanitary sewer shall be less than eight inches in diameter unless otherwise approved by the city. Six-inch sanitary sewer may be approved by the city if the line is no more than 250 feet long and is located at the end of a system with no possibility of being extended. Building sewers shall have a minimum of four-inch inside diameter.

(1) Location. Sanitary sewers, whenever possible, shall be installed within five feet of the centerline of the public right-of-way or on the centerline of easements unless otherwise approved by the city. Sewers shall be installed no closer than five feet to an easement side line or 10 feet to the edge of a public right-of-way. The city may require maintenance access easements.

(2) Alignment. Sanitary sewer lines shall be laid on a straight alignment and uniform grade between manholes.

(3) Grade. All sanitary sewers shall be laid on a grade which will produce a minimum velocity of two feet per second when flowing full or half-full. The minimum grades for various sizes of pipe are listed below:


Inside Pipe Diameter (inches)	Grade (feet per 100 feet)
6	0.60
8	0.40
10	0.28
12	0.22
15	0.15
18	0.12
21	0.10
24	0.08
27	0.07
30	0.06

(4) Steep Slopes. Sanitary sewers on slopes in excess of 20 percent shall be secured through the use of concrete anchor walls. Spacing for anchors shall be as follows:


Minimum Anchor Spacing
Grade (%)	(Center to Center)
20 – 34	35 feet
35 – 50	25 feet
51+	15 feet or concrete encasement

(5) Pipe Cover. Minimum pipe cover shall be in compliance with this section unless an exception is approved by the city.

In paved areas, pipe cover shall be measured from the bottom of the subbase to the upper surface of the pipe barrel. In pavement areas, the pipe bell shall not intrude in to the subbase. In areas without pavement, pipe cover shall be measured from finish grade to the upper surface of the pipe barrel. Minimum cover requirements are as follows:


Type of Pipe	Cover (in.)
Nonreinforced Pipe	36
Ductile Iron	18

(6) Sanitary Sewer in Vicinity of Water Supplies. No sanitary sewer shall be less than 10 feet from any well, spring, or other source of domestic water supply. All sanitary sewers that are located within 50 feet from any such source of domestic water supply shall be constructed of ductile iron water pipe with watertight joints, C-900 PVC, or other city-approved pipe. Sanitary sewers and domestic water lines shall not be laid in the same trench. Parallel water and sanitary sewer lines shall be at least 10 feet apart horizontally. Wherever it is necessary for sanitary sewer and water lines to cross each other, the crossing should be at an angle of approximately 90 degrees. The sanitary sewer shall be located 18 inches or more below the water line or be constructed of ductile iron pipe, have a concrete encasement, or other city-approved pipe material. In such cases, the length of the sanitary sewer pipe shall be centered at the crossing. (Ord. 2875 Appx. § 540.2, 2003)

18.24.120 Manhole design.

Manholes shall be provided at least every 400 feet, at every change in alignment, and at every grade change. A manhole shall be located at the upstream end of the pipe except as allowed in SHMC 18.24.130. Manholes shall not be closer than five feet to a curb line.

All manholes shall be a minimum of 48 inches in diameter. All manholes shall have a minimum 12-inch ledge in the base.

Building sewers are allowed to be connected directly into a manhole providing that they are properly channelized. No more than three building sewers are allowed to be connected to a manhole unless otherwise approved by the city. If any building sewer is connected into a manhole at an elevation more than 12 inches above the top of the ledge, it shall be constructed with an inside drop.

Manholes constructed on lines with 12-inch or smaller pipe shall have at least 0.2 foot of fall through the manhole or as allowed by Oregon DEQ and approved by the city. (Ord. 2875 Appx. § 540.3, 2003)

18.24.130 Clean outs.

Clean outs shall be allowed only on pipelines where the sewer line has no possibility for future extension. The maximum distance between the clean out and a manhole is 150 feet, unless otherwise approved by the city. The standpipe shall be the same size as the pipeline up to a maximum of eight inches.

Temporary clean outs may be installed within the right-of-way at the end of a stub street where the street is expected to be extended in the future and the design of the sewer system does not warrant that a manhole be constructed at this location. When the sewer is extended, the temporary clean out shall be removed. (Ord. 2875 Appx. § 540.4, 2003)

Article V. Technical Specifications

18.24.135 Technical specifications.

The technical specifications contained in this chapter, together with the Oregon Department of Environmental Quality, the Federal Environmental Protection Agency, and the American Public Works Association standards and any other applicable requirement(s) of the city, shall govern the character and quality of material, equipment, installation, and construction procedures for gravity flow portions of public sanitary sewer systems. (Ord. 2875 Appx. § 550, 2003)

18.24.140 Manholes and structures.

(1) Materials.

(a) Aggregate and Portland Cement. Aggregate and Portland cement shall meet the standards set forth in Section 756 of the Oregon Standard Specifications for Construction.

(b) Concrete. Concrete shall conform to the requirement of ASTM C94, Alternate 2. Compressive field strength for manhole bases and miscellaneous concrete structures shall be not less than 3,000 psi at 28 days. Maximum size of aggregate shall be one and one-half inches. Slump shall be between two and four inches.

(c) Manhole Frames and Covers. Casting shall be tough, close-grained gray iron, smooth and clean, free from blisters, blowholes, and all defects, and conform to ASTM A48, Class 30. Covers shall be true and set within ring at all points. Frames and covers shall be standard or suburban, solid, depending upon the type and location of the manhole and as approved by the city. Watertight frames and covers shall be installed on manholes located within floodplain areas, along stream corridors, or where excess surface water may cause inflow problems. Tamper-proof frames and covers shall be installed on manholes in easement areas.

(d) Precast Manholes. Precast manholes shall be concrete. Materials shall conform to the requirements of ASTM C478. Minimum wall thickness shall be five inches. Cones shall have the same wall thickness and reinforcement as riser sections. Joints shall be tongue and groove, rubber ring, or keylock-type. Cones shall be eccentric.

(e) Precast Bases. Precast base sections or manhole bases may be used provided all the details of construction are approved prior to construction.

(f) Pipe Stub Outs for Future Connections. Pipe stub outs for future connections shall be of the same type as approved for use in the lateral, main, or trunk lines. Rubber-gasketed watertight plugs shall be furnished with each stub out and shall be adequately braced against air test pressures.

(g) Manhole Steps. Manhole step material shall be plastic with reinforcing bar, a minimum one-half-inch Grade 60, meeting requirements of ASTM A615 encapsulated with injection-molded copolymer polypropylene with serrated surfaces.

(h) Nonshrink Grout. Nonshrink grout shall be Sika 212, Euco N-S, Five Star, or city-approved equal nonmetallic cementitious commercial grout exhibiting zero shrinkage. Grout shall not be amended with cement or sand and shall not be reconditioned with water after initial mixing. Nonshrink grout shall be placed or packed only with the use of an approved commercial concrete bonding agent. Unused grout shall be discarded after 20 minutes and shall not be used.

(i) Manhole Pipe Connector. Rigid pipe entering or leaving a manhole shall use a flexible connector that is designed to produce a positive watertight connection.

(2) Workmanship on Manholes.

(a) Foundation Stabilization. If unstable material exists that will not support the manhole or other structure, the contractor shall install geotextile fabric or excavate below grade and backfill with foundation stabilization material.

(b) Pipe Connections. Special care shall be taken to see that the openings through which sanitary sewer pipes enter the structure are completely watertight.

(c) Drop Manholes. The maximum fall without an inside drop as measured from the existing flow line to the new flow line is one and one-half feet and shall be constructed with a beaver slide as shown in the standard drawings. When the drop is more than two feet, an inside drop shall be used as shown in the standard drawings.

(d) Poured in Place Concrete Bases. The contractor shall remove water from the excavated area, provide 12 inches minimum layer of compacted three-fourths minus crushed rock for a base, and construct the concrete base so that the first precast manhole section has a uniform bearing throughout the full circumference. There shall be a minimum of eight inches of concrete between the compacted gravel and the lowest invert of the manhole. The contractor shall deposit sufficient concrete on the base to assure a watertight seal between base and manhole wall. Twenty-four hours shall be allowed to elapse before placing the remaining sections on the base.

(e) Placing Manhole Section. The contractor shall clean the end of sections of foreign materials and install the preformed plastic gasket in conformance with the manufacturer’s recommendations.

(f) Manhole Inverts. The contractor shall construct manhole inverts in conformance with details and with smooth transitions to ensure an unobstructed flow through the manhole, and remove all sharp edges or rough sections.

(g) Manhole Extensions, Rings, and Covers. The contractor shall install rings and covers on top of manholes to positively prevent all infiltration of surface or ground water into manholes. Rings shall be set in a bed of nonshrinking grout with the nonshrinking grout carried over the flange of the ring and shall be set so that tops of covers are flush with the surface of adjoining pavement, or one foot above natural ground.

(h) Manhole Taps. Taps into existing manholes shall be core drilled unless approved otherwise by the city. All nonconcrete pipe material used on a manhole tap shall be adapted with a watertight coupling compatible with concrete or approved equal (e.g., inserted manhole boot). The bonding material used to connect the pipe and/or coupling to the manhole must be nonshrink material to ensure no ground water infiltration occurs.

(3) Types of Connections.

(a) Connection to Existing Manholes. The contractor shall connect sanitary lines to existing manholes at locations indicated; provide all diversion facilities and perform all work necessary to maintain sanitary flow in existing sanitary systems during connection to the manholes; and break out existing manhole bases or grouting as necessary and regrout to provide smooth flow into and through existing manholes. The contractor shall allow no debris to enter the existing system while making the connection.

(b) Manholes over Existing Sanitary Sewer Systems. The contractor shall construct manholes over existing sanitary lines at locations shown on plans. Final connection to the existing sanitary sewer shall not be made until the system has been tested in accordance with the requirements of SHMC 18.24.180 and is ready for acceptance as outlined in this chapter. All broken edges shall be covered with nonshrinking grout and troweled smooth. The contractor shall prevent any debris from entering the manhole while breaking into the existing pipe. (Ord. 2875 Appx. § 550.1, 2003)

18.24.150 Sewer pipe and fittings.

(1) General. Sanitary sewer pipe shall have flexible gasket joints. Joints on all fittings shall be the same as the joints used on the pipe. Caps or plugs shall be furnished with each fitting, outlet, or stub as required with the same type gasket and/or joint in the pipe.

(2) Materials.

(a) Polyvinyl Chloride Pipe (PVC). PVC pipe shall be as follows:


Diameter	Type
4″ – 15″	ASTM 3034 SDR 35
18″ – 24″	ASTM F-679 SDR 35
4″ – 12″	ASTM C-900; D-1784 DR

Gaskets shall conform to the requirements of ASTM 477 and ASTM 3212.

Fittings shall conform to the applicable portions of the following specifications: ASTM D1785, ASTM D2729, ASTM D2466, ASTM 2467, ASTM D3033, and ASTM D3034. Fitting joints shall be the same as the pipe joints.

(b) Ductile Iron Pipe. Ductile iron pipe shall conform to the requirements of ANSI A21.50-1 or AWWA C150-1, cement lined push-on joint. The minimum thickness class shall be Class 50 (up through 12-inch diameter pipe) and Class 51 (for 14-inch diameter and larger pipe).

Fittings shall be mechanical or push-on of the class as specified. Mechanical joint cast iron fittings shall conform to AWWA C110 and shall be of a class at least equal to that of the adjacent pipe. Push-on joint fittings shall be gray iron with body thickness and radii of curvature conforming to ANSI A21.10.

(c) Line Tap Fittings. Service laterals installed with new construction of main line(s) shall be manufactured tee connections and will be installed as shown in the standard detail drawings.

PVC tee saddle shall be in accordance with ASTM D-3034 with minimum cell classification of 1245B-C or 12364-C as defined in ASTM D-1784. Elastomeric seals meeting ASTM F-477 specifications, and located at both the lead and skirt ends of the saddle. Stainless steel band shall be a full nine-sixteenths inch wide. This saddle is allowed on PVC, clay, IPS, concrete, asbestos cement, and PE pipe.

Inserta Tee shall meet the same standards as the PVC tee saddle. This saddle is allowed only on thick wall pipe material, e.g., concrete, ductile iron, or rib-type plastic.

(d) Grout. Grout shall be Sika 212, Euco N-S, Five Star, or approved equal nonmetallic cementitious commercial grout exhibiting zero shrinkage per ASTM C-827 and CRD-C-621. Grout shall not be amended with cement or sand and shall not be reconditioned with water after initial mixing. (Ord. 2875 Appx. § 550.2, 2003)

18.24.160 Pipe installation.

(1) Workmanship.

(a) Line and Grade. The contractor shall establish line and grade for pipe by the use of lasers or by transferring the cut from the offset stakes to the trench at whatever intervals necessary to maintain the line and grade. The contractor shall check line and grade as necessary. In the event that the limits prescribed in this chapter are not met, the work shall be immediately stopped, the city notified, and the cause remedied before proceeding further with the work. Variance from the established line and grade shall not be greater than one-thirty-second inch per inch of pipe diameter and shall not exceed one-half inch for line and one-fourth inch for grade, providing that such variation does not result in a level or reverse-sloping invert. Variation in the invert elevation between adjoining ends of pipe shall not exceed one-sixty-fourth inch per inch of pipe diameter, or one-half-inch maximum.

(b) Pipe Handling. The contractor shall unload pipe only by approved means. Pipe shall not be dropped to the ground and shall not be dropped or dumped into trenches. The contractor shall inspect all pipe and fittings prior to lowering into trench to ensure no cracked, broken, or defective materials are used. The contractor shall clean ends of pipe thoroughly, remove foreign matter and dirt from inside of pipe, and keep it clean during laying and joining. The contractor shall lower pipe into the trench in such a manner as to avoid any physical damage to the pipe. The contractor shall remove all damaged pipe from the job site.

(c) Tying to Existing Sanitary Sewer. When a contractor ties into a “live” line, the contractor shall keep the new line plugged at the downstream end of the construction to prevent entry of ground water and debris into the city sanitary sewer system.

(d) Foreign Material. The contractor shall take all precautions necessary to prevent excavated or other foreign material from entering into the pipe during the laying operation. At all times, when laying operations are not in progress, the contractor shall use a mechanical plug at the open end of the last laid section of pipe to prevent entry of foreign materials or creep of the gasketed joints.

(e) Pipe Laying. Pipe laying shall proceed upgrade with spigot ends pointing in the direction of the flow. After a section of pipe has been lowered into the prepared trench, the contractor shall clean the end of the pipe to be joined, the inside of the joint, and the rubber ring (if required) immediately before joining the pipe, and make assembly of the joint in accordance with the recommendations of the manufacturer for the type of joint used. The contractor shall provide all special tools and appliances required for the jointing assembly. After the joint has been made, the pipe shall be checked for alignment and grade. The trench bottom shall form a continuous and uniform bearing and support for the pipe at every point between joints. Pipe should be rotated so that stenciling (pipe size, material, etc.) is on top and visible when pipe is exposed.

(f) Transition Fittings. When joining different types of pipes, the contractor shall use approved ridged fittings. No flexible fittings will be approved. Bell-type couplings are considered flexible and are not acceptable.

(i) Shear ring/ridge transition couplings meeting the ASTM C564 or equal shall be used.

(ii) PVC couplers or adapters shall meet the ASTM 3034-SDR 35/C-900-DR 18-D1784 specifications.

(iii) Ductile iron transition couplings shall meet the ASTM A536-80 for center and end rings, ASTM D2000 3 BA 75 for gaskets and AWWA C-111-80 for bolts and nuts.

(g) Pipe Bedding. The contractor shall install pipe zone material uniformly on both sides of the pipe up to the springline of the pipe. Material shall be compacted to ensure proper support within the haunching area.

(h) Line Taps.

(i) Line taps shall be core drilled unless approved otherwise by the city. Core-drilled holes shall be done using a cylinder-style hole saw for plastic pipe material or a diamond core bit for concrete and ductile iron pipes.

(ii) Prior to installation of the saddle, the area around the saddle installation shall be clean and free of all rough edges.

(iii) While installing the saddle, no rock, dirt, or debris shall be allowed to enter the main sewer line.

(iv) The contractor shall install three-fourths-inch minus gravel in the pipe zone around the line tap, from four inches below the pipe or to undisturbed ground and to six inches above the pipe.

(v) Magnetic tape shall be installed on all building sewers per the standard details. (Ord. 2875 Appx. § 550.3, 2003)

18.24.170 Building sewers.

(1) Service to Lots. Where streets or main line sewers are being constructed as part of a development, individual building sewers shall be constructed to serve each lot.

(a) Installation. All new building sewers being constructed as part of a development shall be installed with a permanent cap for testing purposes and to prevent migration of ground water and other unwanted materials from entering the line. The cap is to remain until the lateral is extended to new building.

Building sewers shall be installed in accordance with the Uniform Building Code (UBC) and Council of American Building Officials (CABO).

(b) Material. Pipes for building sewers shall be one of the following types:

(i) PVC (polyvinyl chloride), conforming to ASTM D3034 (green).

(ii) Ductile iron conforming to Class 50.

(c) Alignment and Grade. Building sewers shall be laid in a straight grade and alignment from the main sewer line to the edge of right-of-way or edge of permanent easement. The grade shall be a minimum of two percent. The pipe shall be laid on a pipe base of four inches of three-fourths-inch minus crushed rock. All plastic pipe shall have three-fourths-inch minus rock placed six inches over the top of the pipe.

(d) Markings. Building sewers shall be marked with a detectable underground magnetic tape. The magnetic tape shall be placed from the main pipeline to the end of the side lateral with 18 inches separation between the tape and pipe. The magnetic tape shall be green in color and have the following marking:

CAUTION SEWER BURIED BELOW

A two-by-four stake shall be installed at the end of the sanitary lateral from the invert of the pipe to three feet above the ground surface. The stake shall be of outdoor wood and marked for sanitary sewer. A magnetic tape shall be placed alongside the two-by-four. (Ord. 2875 Appx. § 550.4, 2003)

18.24.180 Testing and acceptance.

(1) General. All gravity sanitary pipeline shall pass the required air tests, pass a deflection test, be video-inspected, and be free of visible leaks. All projects shall pass the required manhole tests. The contractor shall furnish all necessary testing equipment and perform the tests in a manner satisfactory to the city and Oregon DEQ.

(2) Line Cleaning. Prior to the internal pressure testing and inspection of the system, the contractor shall ball and flush and clean all parts of the system. The contractor shall remove all accumulated construction debris, rocks, gravel, sand, silt, and other foreign material from the system at or near the closest downstream manhole.

(3) Manholes.

(a) General. Sanitary sewer manholes shall be tested for acceptance after the trench has been backfilled, compaction requirements have been met, road base rock has been installed and the street paved, and concrete manhole closure collars have been installed. If the manholes have passed the tests and the castings have been disturbed by construction activities and need to be reinstalled, the manholes shall be retested.

(b) Vacuum Testing. The test will consist of plugging all inlets and outlets. A vacuum of 10 inches of mercury shall be drawn and the vacuum pump shut off. With the valves closed, the time shall be measured for the vacuum to drop to nine inches. Minimum time of test shall be 30 seconds. The manhole shall pass if the time for the vacuum reading to drop to nine inches meets or exceeds the values indicated in the table below:


Depth of Manhole	Allowable Time (seconds)
(feet)	48-inch	60-inch	72-inch
8	20	26	33
10	25	33	41
12	30	39	49
14	35	46	57
16	40	52	65
18	45	59	73
20	50	65	81
22	55	72	89
24	59	78	97
26	64	85	105
28	69	91	113
30	74	98	121

(c) Hydrostatic Testing. The test will consist of plugging all inlets and outlets and filling the manhole with water to the rim. Leakage in each manhole shall not exceed 0.2 gallons per hour per foot of head above the invert. Leakage will be determined by refilling to the rim using a calibrated or known volume container.

(4) Air Testing Pipeline.

(a) General. After construction of the system, including service connections, required compaction testing, and backfilling, the contractor shall conduct a low-pressure air test. The contractor shall provide all equipment and personnel for the test. Tests shall be conducted during normal working hours. Air tests for storm lines will not be required.

(b) Safety. Only qualified personnel shall be permitted to conduct the test. All plugs used to close the sewer for the air test must be capable of resisting the internal pressures and must be securely braced, if necessary. All air testing equipment must be placed above ground and no one shall be permitted to enter a manhole or trench where a plugged line is under pressure. All pressure must be released before the plugs are removed.

(i) Clean the lines to be tested and remove all debris.

(ii) The contractor has the option of wetting the lines prior to testing.

(iii) Plug all open ends with suitable test plugs; brace each plug securely.

(iv) Check the average height of ground water over the line. The test pressures required below shall be increased 0.433 psi for each foot of average water depth over the line.

(v) Add air slowly to the section of system being tested until the internal air pressure is raised to the test pressure specified below.

(vi) After the internal test pressure is reached, at least two minutes shall be allowed for the air temperature to stabilize, adding only the amount of air required to maintain pressure.

(vii) After the temperature stabilization period, disconnect the air supply.

(viii) Acceptance shall be based upon meeting or exceeding the requirements specified by Section 1140 of the Oregon Standard Specifications for Construction.

(ix) Record the diameter (inches), length (feet), end manhole number, time, pressure drop, and ground water level of the test on an inspection form. The recording form shall become a permanent record of the project.

(5) Deflection Test for Flexible Pipe. Sanitary sewers constructed of flexible pipe materials shall be deflection-tested. The test shall be conducted by pulling an approved mandrel through the completed pipeline. The diameter of the mandrel shall be 95 percent of the nominal pipe diameter. The mandrel shall be a rigid, nonadjustable, odd-numbering leg (nine legs minimum) mandrel having an effective length of not less than its nominal diameter.

Testing shall be conducted after the line has been completely balled and flushed out with water. The contractor will be required to locate and repair any section failing to pass the deflection test and to retest the section with air and deflection tests. Air test for storm lines will not be required.

(6) Video Inspection of Gravity Systems. All sanitary sewers shall be video-inspected and taped with an omni-view style camera prior to the city acceptance of the system(s). All pipes shall be thoroughly flushed immediately prior to the video inspection. A one-inch target ball shall be placed in format of the camera. A copy of the videotape and a written TV inspection report shall be supplied to the city. The videotape shall be recorded in color and on VHS format. Any and all problems, deficiencies, and imperfections discovered during the video inspection shall be noted on the videotape and the written report.

(7) Video Inspection for Warranty Acceptance. The city shall conduct video inspection of all sanitary sewer lines after one year of service to determine any defects in the system. Problems found shall be corrected/repaired by the contractor at the contractor/developer’s expense. A new one-year warranty period will apply to all lines requiring repair.

If defects appear to be minor, an extended warranty period to be determined by the city will be required. (Ord. 2875 Appx. § 550.5, 2003)

18.24.190 Prohibited activities.

The discharge, placement, deposit, dumping, or otherwise contributing a solid or liquid material into the public sanitary sewer system, either directly or indirectly, which may obstruct flow or otherwise interfere with the operation or function of a public sanitary sewer facility is prohibited. This shall include, but is not limited to, placing of soil or rock without an approved fill permit, or the dumping of debris, rubbish, trash, or other waste material. (Ord. 2875 Appx. § 550.6, 2003)