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Section 38 – Sewer and Storm Drain Construction

any discrepancy exists, the work shall be stopped and the discrepancy immediately reported to

the Agency. In addition, when requested by the Agency, a string line shall be used in the

bottom of the trench to insure a straight grade and alignment of the pipe.

The Contractor may elect to furnish a laser beam system for grade and alignment control.

Such laser beam shall have a minimum accuracy of ± 0.01 foot per one hundred feet (100’) on

line; and a minimum visible range of one thousand feet (1000’), and shall comply with OSHA

requirements. The laser system shall have good visibility when used with suitable target

material. The laser system shall be of the self-leveling type so that the laser beam is

automatically compensated for small grade disturbances. The laser system shall also have an

early warning system that warns when the laser is off grade.

38-4.03 Grade Tolerance - Sewer

Grade tolerance of the flow line of sewer pipe shall not exceed ± 0.05 feet. In addition, in

any twenty-five-foot (25’) length, the total variation (plus or minus) from flow line grade shall not

exceed the following:

1. one-quarter of an inch (0.25”) in four inch (4”) or smaller pipe

2. three-quarters of an inch (0.75”) in six- through twelve-inch (6”-12”)

3. one inch (1”) in fifteen- through thirty-six-inch (15”36”) pipe.

4. Grade and total variation tolerance for pipe greater than thirty-six inches (36”) shall be as

required in the Special Provisions.

38-4.04 Grade Tolerance – Storm Drain

The elevation of the pipe invert for storm drain pipe shall not deviate from the design

elevation by more than plus or minus two percent (±2%) of the pipe size concerned, or one inch

(1”), whichever is greater. The rate of deviation from grade or returning to grade shall be limited

to one-sixteenth of an inch (1/16”) per foot (1’) of pipe.

38-4.05 Existing Utilities and Facilities

Mortar or brick plugs shall be installed in existing manholes as directed by the Agency in

order to prevent surface water, ground water, and debris from entering existing sewer or storm

drain systems during construction. Inflatable plugs will not be permitted. Care shall be

exercised in installing plugs to avoid interrupting service to existing sewer or storm drain

services. Plugs shall be removed upon completion of testing as provided in Section 38-10,

“Testing of Pipe”, in this Section of these Specifications.

The Contractor is responsible for avoiding all utility, service, or other conflicting lines that are

not in direct physical conflict with the facility under construction. The Contractor may arrange

with the owner of the utility to temporarily disconnect house service lines or other facilities along

the line of work for the Contractor’s convenience. The Contractor is responsible for all costs for

disconnecting and restoring such utilities.

Utility or other lines which are in direct physical conflict with the structural section of the

facility being constructed or appurtenant structures, and which cannot be avoided by rerouting

the facility being constructed, or for which relocation is not provided in the Plans and

Specifications, will be relocated by the owner of the utility prior to or during construction in

accordance with Section 42, “Relocation and Maintenance of Utility Facilities”, of these

Should it become necessary to reroute the facility being constructed to avoid an existing

utility or other obstruction and such rerouting is ordered by the Agency, compensation for the

installation of such rerouted line shall be made at the unit price bid for the installation of said

facility and no additional compensation will be made except as provided in Section 9, “Changes

and Claims”, of these Specifications. Reroute sewer service in accordance with Standard