A. Definitions: For the purpose of this section, the following words and terms shall have the meanings ascribed to them in this subsection:
PIPE OR PIPELINE: Underground piping.
B. Methods Of Pipe Installation: It is intended that piping be installed by constructing open trenches, unless specifically shown otherwise on the drawings. Piping shall not be installed by open cut methods which do not allow the pipe to be bedded in granular material, such as installation with a trenching machine. Piping may be installed by the boring and jacking method, with or without casing piping, as required by the condition of the installation with approval of the village engineer.
C. Application Of Provisions: Excavation and backfill for underground piping shall include all excavation, backfilling, compacting, disposal of surplus material, and all other work incidental to the construction of trenches, including any additional excavation which may be required for manholes or other structures forming a part of the pipeline.
D. Construction Standards: All excavation shall be in accordance with the "Standard Specifications For Water And Sewer Main Construction", latest edition, and the "Standard Specifications For Road And Bridge Construction", IDOT, latest edition.
E. General Requirements:
1. Along the route of the new piping, the surface materials shall be removed only to such widths as will permit a trench to be excavated which will afford sufficient room for proper efficiency and proper construction. Where sidewalks, driveways, pavements, and curb and gutter are encountered, care shall be taken to protect against fracture or disturbance beyond reasonable working limits. Topsoil suitable for final grading and landscaping shall be piled separately, in locations authorized by the village superintendent of public works or the developer's engineer, and preserved so that it may be restored after the remainder of the backfill is so placed.
2. The subdivider may conduct exploratory excavations to determine if an elevation conflict exists between a new pipeline and an existing utility. These exploratory excavations shall be performed far enough in advance of the work so that after consultation with the developer's engineer, any necessary adjustments to the line and grade of the new pipeline can be made.
3. The subdivider may make any exploratory excavation necessary to confirm the correct size, type, and number of fittings or valves required at a particular location.
F. Hand Or Machine Excavations: Where working space will permit, trenches may be excavated by machine; provided, that by so doing, public and private improvements will not be subjected to an unreasonable amount of damage. If, however, excavation by machine methods cannot be made without material damage being done to public and private improvements, hand excavation shall be employed.
G. Width Of Excavation:
1. The trench shall be excavated to an elevation four inches (4") below the bottom of the pipe and so that the flow line of the finished pipeline will be at the depth and grade specified or established by the developer's engineer. For trench depths of five feet (5') or less and when sheeting and shoring is not required, the trench shall be excavated to a minimum width of two feet (2') wider than the external diameter of the pipe, to permit thorough tamping of the material under the haunches and around the pipe. For trench depths of more than five feet (5') and when sheeting or shoring is required, the trench width shall be a minimum of three feet (3') wider than the external diameter of the pipe. The trench shall generally be excavated so that vertical faces are maintained; except, that when authorized by the developer's engineer and when physical conditions and safety will permit, the sides of the trench may be sloped or benched in accordance with OSHA's 29 CFR part 1926, subpart P, excavation standards.
2. If these trench widths are exceeded without the written authorization of the developer's engineer, the pipe shall be installed with a concrete cradle, or with concrete encasement, or a stronger pipe than originally specified shall be used as authorized by the developer's engineer.
H. Excavation Below Grade: In cases where the excavation is carried beyond or below the lines and grades given by the developer's engineer, all such excavated space shall be refilled with suitable granular material.
I. Trench Protection:
1. Generally:
a. Open cut trenches shall be protected in accordance with applicable rules, laws and regulations of federal, state and village ordinances, but shall not be less than the standards and regulations established by the department of labor, occupational safety and health administration, 29 CFR part 1926, occupational safety and health standards - excavations; final rule, hereinafter called OSHA.
b. Protective systems may include two (2) types:
(1) Structural support systems.
(2) Sloping and benching excavation systems.
c. No protective system shall be required for excavations occurring in other than stable rock up to five feet (5') in depth unless the soil has been determined to be subject to potential cave in based on tests and evaluations, or unless it has been found to experience cave in during construction. If the excavation walls for trenches less than five feet (5') in depth are subject to cave in, a protective system shall be used in conformance with sections 20-2.08 and 20-2.09 of the "Standard Specifications For Water And Sewer Main Construction In Illinois".
d. Any trench excavation which exceeds twenty feet (20') in depth and occurs in other than stable rock shall make use of a protective system which is designed and approved by an Illinois licensed structural engineer for a structural support system or an Illinois licensed professional engineer for a sloped and benched excavation system. For trench excavations occurring in other than stable rock of a depth of twenty feet (20') or less, the protection system provided shall conform to the requirements of sections 20-2.08 and 20-2.09 of the "Standard Specifications For Water And Sewer Main Construction In Illinois", latest edition.
e. Surface encumbrances that are located so as to create a hazard to workers in the trench excavation shall be removed or supported by the contractor.
f. Ramps, runways, or ladders shall be provided for ingress and egress of workers from trenches which exceed four feet (4') in depth in accordance with OSHA standards.
g. Water in trenches shall be controlled by the use of water removal equipment. If the trench excavation interrupts the natural flow of surface water, diversion ditches or dikes shall be used.
h. When the stability of adjoining buildings, walls, sidewalks, pavements, bridges, or other structures is endangered by excavation operations, structural support systems such as shoring, bracing, or underpinning shall be used to ensure the stability of the structure. Excavation below the foundation of an adjacent structure which is not located in stable rock shall require either of the following:
(1) An Illinois licensed professional engineer has determined that the structure is sufficiently removed from the excavation so as to be unaffected; or
(2) An Illinois licensed structural engineer has designed and approved a structural support system to provide adequate protection to the structure.
2. Trenches With Sloping Sides:
a. The subdivider may, at his option and expense, where working conditions and right of way permit, and with the approval of the developer's engineer, provide protection to the excavated trench by sloping and benching the walls of the excavation, in lieu of providing a structural support system, with the following limitations:
(1) Only structural support systems shall be used for protection to excavations in traveled streets, highways, or alleys.
(2) Only structural support systems shall be used adjacent to streets, highways, alleys, or sidewalks below the intersection of a one to one (1:1) slope line from the nearest face of the excavation to the edge of the pavement.
(3) Only structural support systems shall be used adjacent to a building or bridge unless an Illinois licensed professional engineer has determined that the building or bridge is in no danger of being affected by the excavation.
b. When trenching with sloping sides is permitted, the slopes shall not extend below the top of the pipe. Trench walls below the top of the pipe shall be vertical, with size and width not exceeding the specified values herein for the size of the pipe.
c. Design of sloping and benching systems shall be in conformance with the OSHA rules and regulations.
J. Excavated Material: All excavated material shall be piled in a manner that will not endanger the work and that will avoid obstructing streets, sidewalks and driveways. Excavated materials suitable for backfilling shall be stockpiled separately on the site. No materials shall be placed closer than two feet (2') to the edge of an excavation. Fire hydrants under pressure, valve pit covers, valve boxes, curb stop boxes, or other utility controls shall be left unobstructed and accessible until the work is completed. Gutters shall be kept clear or other satisfactory provisions made for street drainage. Natural watercourses shall not be obstructed or polluted.
K. Removal Of Water: At all times during construction, equipment shall be provided and maintained to remove and properly dispose of all water entering the excavation or other parts of the work until all work to be performed therein has been completed. No sanitary sewer shall be used for disposal of trench water. No water containing settleable solids shall be discharged into storm sewers. The proposed method for the control of groundwater shall be prepared by the developer's engineer.
L. Safety Requirements:
1. Barricades, Guards And Safety Provisions: To protect persons from injury and to avoid property damage, adequate barricades, construction signs, torches, lights and guards, as required, shall be placed and maintained at the site during the progress of the construction work and until it is safe for traffic to use the roads and streets. All material piles, equipment and pipe which may serve as obstructions to traffic shall be enclosed by fences or barricades and shall be protected by proper lights when the visibility is poor. The rules and regulations of OSHA and appropriate authorities respecting safety provisions shall be observed.
2. Structure Protection: Temporary support, adequate protection and maintenance of all underground and surface structures, drains, sewers, and other obstructions encountered in the progress of the work shall be furnished by the subdivider. Any structures which may have been disturbed shall be restored upon completion of the work.
M. Deviations Occasioned By Structures Or Utilities: Wherever obstructions are encountered during the progress of the work and interfere to such an extent that an alteration in the work is required, the developer's engineer shall have the authority to change the drawing and order a deviation from the line and grade or arrange with the owners of the structures for the removal, relocation or reconstruction of the obstructions. Where gas, water, telephone, electrical, hot water, steam, or other existing utilities are an impediment to the vertical or horizontal alignment of a new pipeline, the developer's engineer shall order a change in grade or alignment or shall direct the subdivider to arrange with the owners of the utilities for their removal.
N. Interruption To Utilities: Prior to proceeding with trench excavation, the subdivider shall contact all utility companies in the area to aid in locating their underground services. The subdivider shall proceed with caution in the excavation and preparation of the trench so that the exact location of underground structures may be determined.
O. Conduit Jacked, Bored Or Tunneled: All work consisting of jacking, boring, or tunneling for pipe installation shall be in conformance with section 20-2.19 of the "Standard Specifications For Water And Sewer Main Construction In Illinois", latest edition.
P. Pipe Bedding:
1. a. "Rigid pipe" may be broadly defined as that which does not depend on side support from trench backfill for its structural integrity, e.g., iron, steel, or concrete pipe. Rigid pipe shall be bedded with granular pipe bedding up to the horizontal centerline of the pipe. Backfill from the horizontal centerline to a level of one foot (1') above the top of the pipe (initial backfill) shall be either of granular backfill or excavated earthen materials.
b. "Flexible pipe" may be broadly defined as that which does depend on side support from trench backfill for its structural integrity, e.g., solid wall ABS, PE, PVC pipe, ABS composite pipe, or corrugated metal pipe. All flexible pipe shall be backfilled with granular pipe bedding to a level one foot (1') above the top of the pipe (initial backfill). Clay pipe is included in this "flexible pipe" category so graded sand will be used for granular pipe bedding and granular backfill in pipe trenches when installing clay pipe.
2. All pipe bedding shall be in conformance with sections 20-2.20 and 20-2.21A of the "Standard Specifications For Water And Sewer Main Construction In Illinois", latest edition.
3. All pipes shall be bedded in well compacted, moist aggregate bedding material at least four inches (4") in depth below the pipe, placed across the entire width of the trench and for the length of the pipe. Material for granular pipe bedding shall be crushed limestone, washed gravel, washed sand, or other granular material authorized by the developer's engineer. Granular pipe bedding shall be placed to the centerline of the rigid pipe and to one foot (1') above the top of the pipe for flexible pipe.
4. For rigid piping (iron, concrete, steel, etc.), the granular pipe bedding for firm, dry trench bottoms shall be crushed limestone, coarse aggregate gradation CA-6 or CA-9 as specified in the "Standard Specifications For Road And Bridge Construction", IDOT, latest edition.
5. For flexible and brittle piping (plastic, clay, copper, corrugated metal pipe, etc.), the granular pipe bedding for firm, dry trench bottoms shall be washed sand, fine aggregate gradation FA 5 or FA 6 as specified in the "Standard Specifications For Road And Bridge Construction", IDOT.
6. PVC sewer pipe shall be bedded and backfilled in general accordance with "Underground Installation Of Flexible Thermoplastic Sewer Pipe", ASTM standard D-2321. The embedment materials shall be class III.
7. When unsuitable soil conditions are encountered in the bottom of the trench, the contractor shall remove unsuitable materials below the depth of the bedding shown on the drawings, and shall replace the material removed with compacted pipe bedding materials authorized by the developer's engineer.
8. In cases where excessively wet conditions exist on the trench bottom, stone larger than those listed above (coarse aggregate gradation CA-1 as specified in the "Standard Specifications For Road And Bridge Construction", IDOT) may be used as ballast to stabilize the bottom; however, the pipe shall not be laid on this large aggregate. Granular pipe bedding is required between the larger aggregate and the pipe.
9. As soon as the condition of the pipe will permit, the entire width of the trench shall be backfilled with moist aggregate to the heights stated above. The aggregate shall be placed longitudinally along the pipe. The elevation of the haunch material on each side of the pipe shall be the same. Special care shall be taken to completely fill the space under the pipe haunches. The aggregate materials shall be placed in maximum six inch (6") layers, loose measurement and compacted by ramming or tamping.
Q. Concrete Cradle: Where, in the opinion of the developer's engineer or the village public works superintendent, subgrade conditions warrant extra precautions for the bedding of pipe, the developer's engineer or the village public works superintendent may order the construction of a concrete cradle to support the pipe. The cradle shall be constructed as directed by the developer's engineer.
R. Backfill:
1. Backfill Above The Pipe Bedding:
a. Method I: Method I applies to pipes installed under yards and unimproved areas. In this method, the trench shall be backfilled with originally excavated materials in a manner which will not dislodge or damage the pipe or cause bridging action in the trench. The material shall be deposited in uniform layers not exceeding twelve inches (12") thick, loose measure. Each layer shall be compacted by ramming or tamping or, if directed by the developer's engineer, shall be inundated or deposited with water. The top of the trench shall be left neatly rounded to allow for settlement. The top four inches (4") shall be topsoil. Any rocks or clods greater than two inches (2") in diameter shall be removed from the topsoil as it is spread.
b. Method II: Method II applies to all pipes installed in all alleys, driveways or parking areas which do not have permanent surfaces or oil and chip surfaces. In this method, the trench from the top of the granular pipe bedding to eight inches (8") below the ground surface shall be backfilled with granular backfill. Then eight inches (8") of temporary aggregate surface course, type B, gradation CA-6 or CA-9, as specified in the "Standard Specifications For Road And Bridge Construction", IDOT, shall be applied so that the finished surface of the aggregate is at the new elevation or matches the existing surface elevation. The temporary materials shall be removed as necessary during the final roadway construction.
c. Method III: Method III applies to all pipes installed beneath existing utilities or structures. In this case, the trench from the top of the granular pipe bedding to at least six inches (6") above the existing utility or structure shall be backfilled with granular backfill. The granular material shall be deposited in uniform layers not exceeding six inches (6") thick, loose measure, and each layer shall be compacted by ramming or tamping. The trench from six inches (6") above the existing utility or structure to the surface shall then be backfilled in accordance with another applicable method: I, II, IV, V, or VI.
d. Method IV: Method IV applies to all pipes installed in any area where the existing or new surface is portland cement concrete. In this case, the trench from the top of the granular pipe bedding to the bottom of the existing or proposed surface shall be backfilled with granular backfill.
e. Method V: Method V applies to all pipes installed beneath oil and chip driveways or streets or bituminous concrete surfaces and all other driveways or streets not covered by method II. In this case, the trench from the top of the granular pipe bedding to twelve inches (12") below the surface shall be backfilled with granular backfill. The top twelve inches (12") of the trench shall be temporary aggregate surface course, type B, CA-6 or CA-9 gradation. The temporary materials shall be removed as necessary during the final roadway construction.
f. Method VI: Method VI applies to all pipes installed in cultivated fields. The backfill shall be placed as in method I; except, that no excavated material shall be allowed within the upper zone originally occupied by topsoil. After the backfill reaches the approximate lower limit of the original topsoil zone, the stockpiled topsoil shall be spread in such a manner that natural settlement will not result in a depression along the sewer route. All rocks and boulders greater than two inches (2") in diameter shall be removed from the topsoil as it is spread.
g. Method VII: Method VII applies to all pipes constructed in the earthen berm. From the top of the pipe bedding to twelve inches (12") below the proposed finish grade, the trench shall be backfilled with class A compacted select excavation materials in eight inch (8") layers. The top twelve inches (12") shall be filled with topsoil.
2. Controlled Low Strength Material: In lieu of the granular pipe backfill required by subsection R3 of this section, controlled low strength material (CLSM) may be used, if authorized by the developer's engineer and the village public works superintendent. The CLSM shall conform to mix 1 for CLSM as specified in section 1019 of the "Standard Specifications For Road And Bridge Construction", IDOT, latest edition. Contractors shall take precautions to prevent pipe dislocation during installation of CLSM.
3. Granular Backfill:
a. Material conforming to this specification for granular backfill shall be placed and compacted in those locations shown in section 12-7-6 of this title. Granular backfill shall be used to fill the trench and shall be compacted by mechanical methods unless such compaction is waived by the developer's engineer.
b. Granular backfill for rigid pipe shall be coarse aggregate gradation CA-6, CA-9, or CA-13 as specified in the "Standard Specifications For Road And Bridge Construction", IDOT, latest edition. Granular backfill for flexible pipe shall be fine aggregate gradation FA-5 or FA-6 as specified in the "Standard Specifications For Road And Bridge Construction", IDOT, latest edition.
c. Materials for granular backfill shall consist of washed sand, stone sand, crushed stone, pit run or crushed gravel. Granular backfill shall be reasonably free from an excess of soft and unsound particles and other objectionable matter. Granular materials from local deposits, graded to the limits specified above, and authorized by the developer's engineer, may be used for granular backfill. At the time of use, the granular backfill shall be free of frozen lumps and foreign materials that may have become mixed with it during handling.
4. Water Jetting Backfill: The water jetting backfill method of trench backfill shall only be allowed in yards.
5. Deficiency Of Backfill Material: Where there is a deficiency of suitable backfill material due to a rejection of part or all of the excavated material as unsatisfactory for backfill purposes, the contractor shall furnish satisfactory backfill material wasted from trench excavation in other locations or from other sources.
S. Sewer And Water Main Separation:
1. General Requirements: Water mains and water service lines shall be protected from sanitary and storm sewers, house service connections and drains. Installation of water mains and sewer mains shall comply with standard drawings 18 through 24 of the "Standard Specifications For Water And Sewer Mains In Illinois", latest edition.
2. Horizontal Separation:
a. Water mains shall be located at least ten feet (10') horizontally from any existing or new drain, storm sewer, sanitary sewer, combined sewer or sewer service connection.
b. Water mains may be located closer than ten feet (10') to a sewer line when:
(1) Local conditions prevent a lateral separation of ten feet (10'); and
(2) The water main invert is at least eighteen inches (18") above the crown of the sewer; and
(3) The water main is either in a separate trench or in the same trench on an undisturbed earth shelf located to one side of the sewer.
c. When it is impossible to meet either of the conditions in this subsection S2 or subsection S3 of this section, both the water main and drain or sewer pipe shall be constructed of push on or mechanical joint ductile iron pipe or PVC SDR rated pipe equivalent to water main standards of construction. The drain or sewer shall be pressure tested to the maximum expected surcharge head before backfilling.
3. Vertical Separation:
a. A water main shall be separated from a sewer pipe so that its invert is a minimum of eighteen inches (18") above the crown of the drain or sewer pipe whenever water mains cross storm sewers, sanitary sewers or sewer service connections. The vertical separation shall be maintained for that portion of the water main located within ten feet (10') horizontally of any sewer or drain crossed. A length of water main pipe shall be centered over the sewer pipe to be crossed with joints equidistant from the sewer or drain pipe.
b. Both the water main and sewer pipe shall be constructed of push on or mechanical joint ductile iron pipe or PVC SDR rated pipe equivalent to water main standards of construction when:
(1) It is impossible to obtain the proper vertical separation as described in subsection S3a of this section; or
(2) The water main passes under a sewer or drain pipe.
c. A vertical separation of eighteen inches (18") between the invert of the sewer or drain pipe and the crown of the water main shall be maintained where a water main crosses under a sewer; there shall be support for the sewer or drain pipes to prevent settling and breaking the water main, as shown in section 12-7-6 of this title, as authorized by the developer's engineer. Construction shall extend on each side of the crossing until the perpendicular distance from the water main to the sewer or drain pipe is at least ten feet (10').
4. Prohibition: No water main shall pass through or come into contact with any part of a sewer or sewer manhole.
T. Repair Of Existing Drain Tiles And Storm Sewers:
1. Drain tiles and storm sewers broken during the trench excavation shall be repaired so their carrying capacities shall not be impaired. Broken drain tiles shall be replaced with larger sized piping, either PVC plastic pipe SDR-26 or ductile iron pipe, as shown in section 12-7-6 of this title. The length of the pipe shall be such that it extends a minimum of ten feet (10') on either side of the water main. All repairs of drain tile encountered shall be observed by the developer's engineer or a representative of the village prior to backfilling. Compacted granular backfill will be required as for any existing utility or structure. The pipe to field tile junction shall be wrapped with burlap and encased in concrete. Care shall be taken to prevent concrete from entering the flow line of the pipe.
2. Drain tiles and storm sewers uncovered during the trench excavation which are laid parallel to the trench shall be protected and kept in service. Those tiles or storm sewers accidentally broken shall be repaired or replaced. If necessary, they shall be rerouted around the improvements.
U. Conflict Manholes: Drain tile or storm sewers discovered to be at the same elevation as a wastewater sewer under construction may be handled as follows:
1. A manhole will be constructed at the intersection of the pipes.
2. A sixteen foot (16') minimum section of ductile iron pipe will be laid through the manhole (centered on the manhole) and will be connected to and become a part of the wastewater sewer. Connection of dissimilar pipes shall be made with suitable couplings and concrete encasement.
3. The drain tile or storm sewer shall be connected to the manhole but not laid through it.
V. Ditch Reconstruction: Where ditches have been altered or ruined by construction procedures, it shall be the responsibility of the contractor to regrade the ditch to drain. The shape of the ditch, back slopes, etc., shall be equivalent to that existing prior to pipeline construction.
W. Existing Sewer Removal: Where called for on the drawings, or required for proper operation of new piping, existing piping shall be removed and disposed of off site. All castings and/or valves shall be salvaged and turned over to the village. Where new sewers are at the same location and depth as existing sewers, the existing sewers shall be removed as the excavation is made for the new sewers. (Ord. 2007-19, 5-21-2007)