CHAPTER 3
CONSTRUCTION DETAILS
Section 3301. (previously 3026). Excavations.
Excavations shall be made in such direction and such widths and depths as will give suitable room for properly constructing the sewers and appurtenances to the lines and grades shown on the plans.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3302. (previously 3027). Minimum Width.
For sewers in trenches and tunnels, the minimum width at the top of the sewer pipe shall be 12 inches more than the exterior diameter of the pipe (assumed as six inches on each side of the pipe), exclusive of bells and branches, adding in each case sufficient width to permit placing of sheeting and shoring if required. Refer to Standard Drawing No. 6.
(Added, §1, Ord. 35, 04-06-59)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3303. (previously 3028). Maximum Width.
The maximum width of trench excavation at the top of the sewer pipe, which includes the width required for sheeting and shoring, if necessary, shall be 24 inches more than the outside diameter of the pipe (assumed as 12 inches on each side of the pipe), exclusive of bells and branches. Refer to Standard Drawing No. 6.
(Added, §1, Ord. 35, 04-06-59)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3304. (previously 3029). Excessive Trench Width.
Trench width shall be as shown on Standard Drawing No. 6. If the maximum allowable width is exceeded, except as may be provided for in the plans or by written direction of authorized District representative, the contractor shall furnish all materials, labor, tools, and implements and processes together with all else necessary to provide additional bedding, another more stringent type of bedding, or higher strength pipe as directed by the District or its appointed representative at no additional cost to the District.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 138, 07-01-05)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3305. (previously 3030). Casing, Boring Tunnels and Pipe Bursting.
Sewers which are not to be installed by open cut method may be constructed by casing, boring tunnels, pipe bursting or method approved by authorized District personnel.
(a) Casing Installation.
(1) The minimum inside diameter of the pipe casing shall be 12 inches greater than the maximum outside diameter of the carrier pipe of the sewer to be installed therein.
(2) The casing sections shall be excavated and backfilled in accordance with the requirements of Alameda County Public Works Agency and/or applicable governing authority.
(3) The guide rails for the jacking machine shall be accurately set so that the casing while being jacked will be guided to correct line and grade and to enable the sewer pipe to be centered in the casing.
(4) Voids created between the outside of the casing wall and surrounding earth by pulled or adjusted casings shall be filled as required or approved by the authorized District representative.
(5) When the casing has been completed and before the sewer is installed, it shall be inspected and approved by the authorized District representative or Inspector. Pipe material as shown on the plans shall then be joined and installed on proper grade through the casing.
(6) It is recommended that the contractor make frequent checks on the casing grade during installation.
(7) The sewer pipe shall be securely supported through the casing on the pipe barrel only. If wood is used for supporting the pipe, it shall be structural grade redwood.
(8) After the sewer pipe is installed, it shall be given a preliminary air test in the presence of authorized District representative or Inspector. After the test is satisfactorily completed, the annular space between the pipe and the casing shall be filled with dry sand, mechanically blown in, so as to completely fill all voids after which the space between the end of the casing and the pipe shall be sealed to a watertight condition.
(b) Sewer through Bore. Unless a casing is required by an authorized District representative, building sewer pipe that cannot be installed by open cut methods shall be bored.
(1) When a sewer pipe is to be installed in a bored hole, the hole shall be bored by use of a machine which will cut a true circular bore to the required line and grade. Bored tunnels shall be no more than two inches larger in diameter than the maximum outside diameter of the sewer pipe to be placed therein.
(2) When the bore has been completed and before the sewer is installed, it shall be inspected and approved by the Inspector. Cast iron pressure pipe shall then be joined and installed through the bore.
(3) After the sewer pipe is installed, it shall be given a preliminary air test in the presence of the Inspector. After this test is satisfactorily completed, the annular space between the pipe and the bore at each end shall be sealed to a watertight condition. Sand will not be required to be blown in between the pipe and the bore unless specifically required by authorized District representative.
(c) Pipe Bursting. Unless casing or boring is required by authorized District representative, sewer main and building sewer pipe may be installed via pipe bursting when the sewer is not to be installed by open cut method.
(1) Pipe bursting shall be installed using a constant tension system with a hydraulic or pneumatic bursting device that breaks apart the existing pipe. The void created by the bursting device shall be sufficient in size to accommodate the replacement pipe.
(2) Sections of HDPE pipe shall be joined into continuous lengths on the job site above ground. The joining method shall be heat fusion method (i.e., butt, saddle, or socket) and/or electrofusion method, and shall be performed in strict accordance with the pipe manufacturer’s recommendation.
(3) The sewer main and building sewer pipe shall be inspected and approved by authorized District representative or Inspector. After the pipe is installed, it shall be tested per Section 3411 of this Code in the presence of the Inspector to determine an air or watertight seal.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 52, 08-05-75)
(Amended, §1, Ord. 133, 01-07-03)
(Amended, §1, Ord. 138, 07-01-05)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
(Amended, §1, Ord. 174, 11-07-17)
Section 3306. (previously 3031). Pipe Foundations.
Excavation for sanitary sewers shall be carried to a depth to allow six inches below the outside surface of the pipe when the invert of the pipe is set to designed grade. The bottom of the trench shall be brought up to exterior bottom of the pipe with pipe embedment material as specified in Section 3210 of this Code and thoroughly compacted as specified in Section 3408 of this Code so as to completely support the pipe throughout the entire length of the barrel. The subgrade for the pipe shall be understood to be the exterior bottom of the pipe. Excavations shall be made for pipe bells.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 68, 06-09-82)
(Amended, §1, Ord. 86, 02-06-90)
(Amended, §1, Ord. 133, 01-07-03)
(Amended, §1, Ord. 138, 07-01-05)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3307. (previously 3032). Obstructions.
In the event that storm sewers or appurtenances thereto or any obstruction whatsoever are encountered or a connection to any existing pipe line may be facilitated by a change of grade of the sewer, the contractor shall, at his own cost and expense, make any grade change that the Inspector may direct to properly clear any such obstruction or to facilitate the making of any such connection. Any change in grade shall be approved by the Inspector prior to work being performed.
For capital improvement projects awarded by the District Board of Directors, the contractor may utilize the modification procedures outlined in the contract documents for changes to the work.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 138, 07-01-05)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3308. (previously 3033). Disposal of Excavated Material.
All material excavated and not required for backfilling shall be immediately removed and disposed of. Surplus excavated material shall not be dumped or spread on or along private property, unless written permission is furnished the District, signed by the owner of the property involved, nor shall surplus excavated material be dumped or spread on any portion of any County road unless written permission is furnished to the District signed by the County Surveyor of Alameda County.
Disposal of all construction related materials shall comply with Article V, Chapter 7 of this Code.
(Added, §1, Ord. 35, 04-06-59)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3309. (previously 3034). Shoring, Lagging and Bracing.
The contractor shall furnish, put in place, and maintain such shoring, timbering, lagging, and bracing, etc., both in open cut and tunneling, as may be required to support the sides of the excavation and prevent any movements as set forth in the rules, orders, and regulations established by the California Department of Industrial Relations, Division of Occupational Safety & Health (Cal/OSHA).
The contractor shall be responsible for any injury which may result to any person or persons, structure or structures, or to any interests whatsoever that is due directly or indirectly to the insufficiency of said shoring, timbering, lagging, and bracing, or to the replacing or removal of said shoring, timbering, lagging, and bracing.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 52, 08-05-75)
(Amended, §9, Ord. 60, 11-06-78)
(Amended, §1, Ord. 138, 07-01-05)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3310. (previously 3035). Control of Water.
The contractor shall control all waters encountered during the work in a manner satisfactory to the District.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 52, 08-05-75)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3311. (previously 3036). Foundation Surfaces.
Care shall be taken to preserve manhole and all sewer facility foundation surfaces in an undisturbed condition during construction. If the contractor excavates or disturbs the foundation surfaces, he shall replace such foundation with approved material as specified in Section 3210 or 3408 of this Code to an equal bearing value with the undisturbed foundation.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 97, 09-01-92)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3312. (previously 3037). Manhole Base Reconstruction.
Where reconstruction of the manhole base is necessary to permit installation of a new sewer main through an existing manhole, the contractor shall make the installation by cutting a trench through the existing concrete base of the manhole. The width of the trench shall be wide enough to permit placement of three inches of Class 2 concrete on both sides of the pipe. Where possible the pipe will be laid through the manhole and the top broken out to pipe springline after the concrete in the base has set. Where removal of concrete extends to bottom of manhole base, the material below the pipe cutout shall be over excavated to provide a minimum concrete thickness of six inches below the bottom of the new sewer installation. All manhole base reconstruction shall adhere to Castro Valley Sanitary District Standard Drawing No. 20. Waterstops, Duraseal flexible gasket or approved equal shall be required to be installed a maximum of two feet from the manhole base when connecting a new sewer main to an existing sewer manhole. The manhole barrel shall be protected with Sika non-shrink grout to seat the gasket.
(Added, §8, Ord. 57, 08-02-77)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
(Amended, §1, Ord. 174, 11-07-17)
(Amended, §1, Ord. 183, 09-03-19)
Section 3313. (previously 3038). Pipe Cover and Clearance.
Minimum pipe covers and clearances shall be maintained in the design and construction of sanitary sewers and other subsurface installations. Minimum cover requirements are based on pipe material and surface loading: VCP and HDPE pipe material – four feet minimum in traveled ways subject to vehicular traffic; DIP and CIP pipe material – two feet minimum in all areas.
All crossings of sanitary sewer by other subsurface installations and sanitary sewer crossings of other subsurface installations shall adhere to Castro Valley Sanitary District Standard Drawing No. 5, Method of Bridging. Each location not meeting the minimum cover and clearance requirements will require written approval by authorized District representative for each case.
A construction safety zone of five feet from center line of pipe is defined on all main sewers. Any infringement into this construction safety zone requires written notification to the District.
Any planned improvements by subsurface operators or contractors within the Castro Valley Sanitary District service area shall maintain minimum cover and clearances as set forth in this Code. The operator or contractor shall submit plans and specifications to the District prior to publicly bidding such contemplated work.
(Added, §2, Ord. 128, 04-01-01)
(Amended, §1, Ord. 133, 01-07-03)
(Amended, §1, Ord. 138, 07-01-05)
(Amended §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)
Section 3314. (previously 3054). Filled Areas.
Fill shall be placed to a level providing not less than the minimum required cover for sewers, compacted and certified by the Soils Engineer in responsible charge of the fill placement prior to installation of sewers.
(Added, §1, Ord. 35, 04-06-59)
(Amended, §1, Ord. 52, 08-05-75)
(Amended, §1, Ord. 150, 07-01-09)
(Amended, §1, Ord. 162, 07-01-14)
(Amended, §1, Ord. 169, 05-03-16)