Mission Viejo Municipal Code Div. 12 Earthwork

(a) Earthwork shall include all necessary clearing, grubbing, grading and excavation for pipelines and appurtenances, backfilling, compaction and disposal of excess excavated material all as required for the complete performance of the work for the installation of sewers, manholes, special structures and appurtenances all as indicated on the plans and as specified herein.

(b) Earthwork, including grading, as referred to herein or in connection herewith, shall be construed as including any or all of the following described operations: clearing of the construction site; excavation of all classes and of whatever substance encountered; backfilling; fine grading as finish for unpaved areas; preparation of right-of-way, subgrade for pipe, structures and paving; and performing any other similar, incidental or appurtenant earthwork operation which may be necessary to properly complete the entire work indicated and specified.

(Ord. No. 88-12, § 9(7-4-243), 6-27-88)

Areas where work is to be performed shall be cleared of all trees, shrubs, rubbish and other objectionable material of any kind which, if left in place, would interfere with the proper performance or completion of the contemplated work, would impair its subsequent use or form obstructions therein. Organic material from clearing and grubbing operations will not be incorporated in excavation backfill.

(Ord. No. 88-12, § 9(7-4-244), 6-27-88)

Excavation for sewer pipe, fittings and appurtenances shall be open trench to the depth and in the direction necessary for the proper installation of the same as shown on the plans or as otherwise approved by the department. Any water which may be encountered or may accumulate in the excavation shall be pumped out or otherwise removed as necessary to keep the bottom of the excavation free and clear of water during the progress of the work. Tunneling may be permitted as indicated by economy of construction or necessity of preserving existing improvements. If the earth in the tunnel sloughs off, the roof of the tunnel shall be broken down and the trench excavated as an open trench.

(Ord. No. 88-12, § 9(7-4-245), 6-27-88)

Except by special permission of the department, the maximum length of open trench shall not exceed 1,500 feet in the aggregate at any one location including excavation, construction, pipe laying and embankment.

(Ord. No. 88-12, § 9(7-4-246), 6-27-88)

(a) The overall trench width shall not be more than 16 inches or less than 12 inches wider than the largest outside diameter of the pipe to be laid therein, measured at a point 12 inches above the top of the pipe exclusive of branches. Excavation and trenching shall be true to line so that a clear space of not more than eight inches or less than six inches in width is provided on each side of the largest outside diameter of the pipe in place. For the purpose of this article, the largest outside diameter shall be the outside diameter of the bell on bell-and-spigot pipe.

(b) Where the trench width, measured at a point 12 inches above the top of the bell of the pipe, is wider than the maximum set forth above, the trench area around the pipe shall be backfilled with class C concrete to form a cradle for the pipe as shown on the detail drawings. Alternate methods of backfilling may be submitted by the applicant for approval by the department and the department may approve such alternate method when in its judgment it will afford adequate protection to the piping.

(Ord. No. 88-12, § 9(7-4-247), 6-27-88)

The applicant shall take the necessary precautions to be consistent with the rules, orders and regulations of the division of industrial safety of the state. Excavations shall be so braced, sheeted and supported that they will be safe, and the ground alongside the excavation will not slide or settle, and all existing improvements of any kind, either on public or private property, will be fully protected from damage. The sheeting, shoring and bracing shall be so arranged as not to place any stress on portions of the completed work until the general construction thereof has proceeded far enough to provide ample strength. Care shall be exercised in the drawing or removal of sheeting, shoring, bracing and timbering to prevent the caving or collapse of the excavation faces which are being supported.

(Ord. No. 88-12, § 9(7-4-253), 6-27-88)

Where excavation is inadvertently carried below subgrade and/or foundation elevations, suitable provision shall be made by the applicant for adjustment of same, as directed by the department to meet requirements incurred by the deeper excavation beneath pipe or structures. Overdepth excavation in such locations shall be rectified by backfilling with approved and/or graded gravel, and shall be compacted to provide a firm and unyielding subgrade and/or foundation, as directed by the department.

(Ord. No. 88-12, § 9(7-4-254), 6-27-88)

The applicant shall control grading in a manner to prevent water running into excavations. Obstruction of surface drainage shall be avoided and means shall be provided whereby storm and waste water can flow uninterruptedly in existing gutters, other than surface drains or temporary drains.

(Ord. No. 88-12, § 9(7-4-255), 6-27-88)

(a) The applicant shall provide and maintain at all times during construction ample means and devices with which to promptly remove and properly dispose of all water from any source entering the excavations or other parts of the work. Dewatering shall be accomplished by methods which will insure a dry excavation and preservation of the final lines and grades of the bottoms of excavations. Such methods may include well points, sump points, suitable rock or gravel placed below the required bedding for drainage and pumping purposes, temporary pipelines and other means, all subject to the approval of the department.

(b) Dewatering for the structures and pipelines shall commence when groundwater is first encountered, and shall be continuous until such time as water can be allowed to rise in accordance with the provisions of this section. No concrete footings or floors shall be laid in water nor shall water be allowed to rise over them until the concrete or mortar has set at least eight hours. Water shall not be allowed to rise unequally against walls for a period of 28 days.

(c) Groundwater shall not be allowed to rise around the pipe until jointing compound in the joints has set hard.

(Ord. No. 88-12, § 9(7-4-256), 6-27-88)

Wherever the term "granular soil" is used in this division, it shall be defined as a soil having a minimum sand equivalent of 30 as determined in accordance with state division of highways, Test No. "California 217," and not more than 20 percent of it will pass through a 200 mesh sieve.

(Ord. No. 88-12, § 9(7-4-257), 6-27-88)

The trench bottom shall be graded to provide a smooth, firm and stable foundation at every point throughout the length of the pipe. At each joint in the pipe, the bottom of the trench shall be recessed in the firm foundation in such a manner as to relieve the bell of the pipe of all load, and to insure continuous bearing along the pipe barrel upon the firm foundation. Should large gravel and cobbles be encountered at the trench bottom or pipe subgrade, they shall be removed from beneath the pipe and replaced with clean granular material which shall be compacted to provide uniform support and a firm foundation. The applicant shall be responsible for accurately shaping the pipe subgrade and fitting the bottom of the pipe to the excavation for the width shown on the "bedding details." Use of a drag templet shaped to conform to the outer surface of the pipe will be required if other methods do not give satisfactory results.

(Ord. No. 88-12, § 9(7-4-263), 6-27-88)

Where rock is encountered, it shall be removed below grade and the trench backfilled with clean imported sand to provide a compacted foundation cushion with a minimum allowable thickness of three inches under the outside diameter of the pipe bell.

(Ord. No. 88-12, § 9(7-4-264), 6-27-88)

If excessively wet, soft, spongy, unstable or similarly unsuitable material is encountered at the surface upon which the bedding material is to be placed, the unsuitable material shall be removed to a depth as determined in the field by the department.

(Ord. No. 88-12, § 9(7-4-265), 6-27-88)

Where the trench excavation and pipe foundation and/or subgrade consist of granular or sandy material, the pipe shall be bedded in the material found in the trench as hereinafter specified. In the event the trench excavation material and pipe foundation are not an acceptable granular material for bedding, an imported or selected granular material shall be used for bedding. In all cases, the material to be used for pipe bedding will be subject to the approval of the department.

(Ord. No. 88-12, § 9(7-4-266), 6-27-88)

(a) All trenches shall be backfilled after pipe, fittings and appurtenances have been installed. Whenever a relative compaction requirement value is specified herein, the optimum moisture content and relative density shall be determined in accordance with state division of highways, Test No. "California 216."

(b) All wood and waste material shall be removed from excavation preparatory to backfilling. Backfill material shall be approved in all cases by the department and shall be free of trash, wood, large rock or other objectionable debris. Backfilling shall include the refilling and compacting of the fill in trenches or excavations up to the subgrade of the street or to the existing ground surface.

(Ord. No. 88-12, § 9(7-4-267), 6-27-88)

The pipe shall be carefully bedded by hand placing and compacting and/or consolidating select or imported granular backfill material from the pipe foundation to the upper limit of the pipe zone. The pipe zone shall be considered to extend from the pipe foundation to 12 inches above the top of the outside diameter of the pipe bell. Imported granular material will be used for pipe bedding when excavated materials are not suitable or when required by the bedding detail indicated on the construction drawings.

(Ord. No. 88-12, § 9(7-4-273), 6-27-88)

Selected backfill material consisting of loose earth or sand free from stones, clods or other deleterious material shall be placed in the trench simultaneously on each side of the pipe for the full width of the trench in layers of about six inches in depth. Each layer shall be thoroughly compacted, or consolidated when approved by the department, to a relative density of 90 percent. Care shall be exercised in backfilling to avoid damage to the pipe.

(Ord. No. 88-12, § 9(7-4-274), 6-27-88)

The remaining portion of the trench to within 2½ feet of the roadway surface or ground surface, as the case may be, shall be backfilled, compacted and/or consolidated by approved methods to obtain a relative density of 90 percent. Backfilling shall be done with good, sound earth, sand or gravel and no oil cake, bituminous pavement, concrete, rock or other lumpy material shall be used in the backfill unless these materials are scattered and do not exceed six inches in any dimension, and are not placed within one foot of the 2½-foot limit. Material of a perishable, spongy or otherwise improper nature shall not be used in backfilling, and no material greater than four inches in any dimension shall be placed within one foot of any pipe, manhole or structure.

(Ord. No. 88-12, § 9(7-4-275), 6-27-88)

In open fields across private property within easements, where paving or structures will not be above the excavated area, backfill above the pipe zone to the top of the trench shall be compacted and/or consolidated by approved methods to obtain a density equal to the density of the adjacent undisturbed soil but not less than a relative density of 90 percent.

(Ord. No. 88-12, § 9(7-4-276), 6-27-88)

(a) The top 2½ feet of the trench within roadbed areas shall be compacted in horizontal layers not exceeding eight inches in thickness, using approved hand, pneumatic or mechanical type tampers to obtain a relative density of 90 percent. Flooding and jetting will not be permitted in this upper 2½ feet.

(b) From existing street grade to 2½ feet below street grade, the material for backfill may contain stones ranging in sizes up to two inches in diameter in quantity not exceeding 20 percent of the volume where the coarse materials are well-distributed throughout the finer material and the specified compaction can be obtained.

(Ord. No. 88-12, § 9(7-4-277), 6-27-88)

Compaction shall be done by use of vibratory equipment, tamping rollers, pneumatic tire rollers or other mechanical tampers of the type and size approved by the department. The backfill shall be placed in horizontal layers of such depths as are considered proper for the type of compacting equipment being used in relation to the backfill material being placed. Each layer shall be evenly spread, properly moistened and compacted to the specified relative density in section 6.60.1254. The applicant shall repair or replace any sewer pipe fittings, manholes and/or structures as directed by the department where damaged by the applicant's operations.

(Ord. No. 88-12, § 9(7-4-283), 6-27-88)

Consolidated fill shall be performed by flooding, poling or jetting so as to obtain a relative density of the fill material at least equal to that specified in section 6.60.1254. When flooding, poling or jetting methods are used, material for use as backfill shall be placed and consolidated in layers not exceeding four feet in thickness. Flooding, poling or jetting methods shall be supplemented by the use of vibratory or other compaction equipment when necessary to obtain the required relative density. Care shall be taken in all consolidating operations to prevent the movement or floating of the sewer pipe. Consolidation methods shall not be used where the backfill material is not sufficiently granular in nature to be self-draining during and after consolidation, or where foundation materials may be softened or otherwise damaged by the quantities of water applied. The applicant shall rectify any misalignment of the pipe because of consolidation operations as directed by the department.

(Ord. No. 88-12, § 9(7-4-284), 6-27-88)

The applicant will engage the services of an approved testing laboratory to determine the relative density of the backfill. The relative density shall be determined in accordance with the methods specified by the state division of highways, Test No. "California 216." If the backfill fails to meet the relative density requirements set forth herein, the applicant shall rework the backfill until the requirements are complied with. The applicant shall make all necessary excavations for density tests as directed by the department.

(Ord. No. 88-12, § 9(7-4-285), 6-27-88)

(a) The applicant shall make the necessary arrangements for, and shall remove and dispose of all excess excavated material.

(b) It is the intent of this division that all surplus material not required for backfill or fill shall be disposed of by the applicant outside the limits of the public rights-of-way and/or easements, and shall be subject to all provisions and regulations of the excavation and grading code of the county.

(c) No excavated material shall be deposited on private property unless written permission from the owner thereof is secured by the applicant. Before the department will accept the work, the applicant shall file a written release signed by all property owners with whom he has entered into agreements for disposal of excess excavated material absolving the department from any liability connected therewith.

(Ord. No. 88-12, § 9(7-4-286), 6-27-88)

Whenever the excavated material is not suitable for backfill, the applicant shall arrange for and furnish suitable imported backfill material, which is capable of attaining the required relative density. He shall dispose of the excess trench excavation as specified in the preceding section. The backfilling with imported material shall be done in accordance with the methods described herein.

(Ord. No. 88-12, § 9(7-4-287), 6-27-88)

Structure excavation shall include the removal of all material of whatever nature necessary for the construction of structures and foundations in accordance with the plans and this division. The sides of excavations for structures shall be sufficient to leave at least two feet in the clear as measured from the extreme outside of formwork or the structure as the case may be. Where excavation is inadvertently carried below designated elevations, suitable provision shall be made by the applicant for adjustment of construction, as directed by the department to meet requirements incurred by the deeper excavation. No earth backfill will be permitted to correct overdepth excavation beneath structures, and overdepth excavation in such locations shall be rectified by backfilling with sand, graded gravel or concrete as directed by the department.

(Ord. No. 88-12, § 9(7-4-293), 6-27-88)

After structures and foundations are in place, backfill shall be placed to the original ground line or to the limits designated on the plans. No material shall be deposited against the walls of concrete structures for a period of 14 days following pouring of concrete.

(Ord. No. 88-12, § 9(7-4-294), 6-27-88)

Backfill material shall consist of loose earth or sand free from stones, clods or other deleterious materials. When material from the excavation is unsuitable for use in backfill, it shall be disposed of as specified in section 6.60.1269 above, and suitable material, which is capable of attaining the required relative density, shall be used in its place.

(Ord. No. 88-12, § 9(7-4-295), 6-27-88)

Backfill shall be placed in horizontal layers not exceeding six inches in depth and shall be moistened and thoroughly tamped, rolled or otherwise compacted to a minimum relative density of 90 percent in accordance with the provisions of section 6.60.1245 above. Water settling will not be permitted except with the written permission of the department.

(Ord. No. 88-12, § 9(7-4-296), 6-27-88)

After backfill has been completed, the job site shall be dressed smooth and left in a neat and presentable condition.

(Ord. No. 88-12, § 9(7-4-297), 6-27-88)