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Home My WebLink About2960-5AGENCY's STANDARD SPECIFICATIONS FOR PIPE BEDDING AND TRENCH BACKFILL September 1998 PART 1 - GENERAL 1-1. SCOPE. This section covers pipe bedding and trench backfill and shall include the necessary materials and construction for pipe embedment, identification markers, and trench backfill. PART 2 - Materials 2-1. Granular Fills. Granular fill material shall be crushed rock or gravel; shall be free from dust, clay, and trash; and shall be graded 1" to No. 4 [25 to 4.75 mm] as defined in ASTM C33. 2-2. Granular Embedment. Granular embedment materials shall be coarse grained native soils or imported sand with a minimum sand equivalence of 30 and of such size that 90 to 100 percent shall pass a number 4 sieve and no more than 5 percent will pass a #200 sieve. They shall be free from dust, clay, trash, and or debris. 2-3. Graded Gravel. Gravel for compacted backfill shall conform to the following gradation and shall not vary from the low limit on one sieve to the high limit on the adjacent sieve or vice versa, but shall be well graded from coarse to fine: Percent Sieve Size Passing by Weight 1 1/2 inch [37.5 mm] 100 1 inch [25 mm] 95-100 314 inch [19 mm] 70-90 3/8 inch [9.5 mm] 40-65 No. 4 [4.75 mm] 25-45 No. 8 [2.38 mm] 15-30 No. 200 [75 lam] 2-10 The gravel mixture shall contain no clay lumps or organic matter. The fraction passing the No. 4 [4.75 mm] sieve shall have a liquid limit not greater than 25 and a plasticity index not greater than 5. 2-4. Filter Fabric. Filter fabric shall be a nonwoven fabric consisting of only continuous chains of polymeric filaments or yarns of polyester formed into a stable network by needle punching. The fabric shall be inert to commonly encountered chemicals; shall be resistant to mildew, rot, ultraviolet light, insects, and rodents; and shall have the following properties: Property Test Method Unit Minimum Average Roll Value (weakest principal direction) Fabric Weight ASTM D3776 oz/yd2 (g/m2) 5.7 [193] Grab Strength ASTM D4632 Ib [N] 155 [689] Grab Elongation ASTM D4632 Percent 60 Mullen Burst ASTM D3786 psi [MPa] 190 [1.3] Strength Apparent Opening CW -02215 U.S. Standard 70 [212 um] Size Sieve Size The filter fabric shall be provided in rolls wrapped with protective covering to protect the fabric from mud, dirt, dust, and debris. 2-5, Identification Tape. Conduits PART 3 - Execution 3-1. FOUNDATION PREPARATION. The upper 8 inches of foundation subgrades for concrete structures and trench bottoms shall be scarified, moisture conditioned, and compacted to 90 percent of maximum dry density at a moisture content ranging from -2 to +2 percent relative to the optimum moisture content as determined by ASTM D1557. QRQFESSI W No. 045935 c- ' c` � Exp. 12/31 /02 CF CA4,E6 / SHOULD CONSTRUCTION OF THE REQUIRED IMPROVEMENTS NOT COMMENCE WITHIN TWO YEARS OF THE DATE OF APPROVAL SHOWN HEREON AND CARRIED FORTH IN A DILIGENT MANNER THE CITY ENGINEER MAY REQUIRE REVISIONS TO THE PLANS TO BRING THEM INTO CONFORMANCE WITH CONDITIONS AND STANDARDS IN EFFECT 3-2. STABILIZATION. Subgrades for concrete structures and trench bottoms shall be firm, dense, and thoroughly compacted and consolidated; shall be free from mud and muck; and shall be sufficiently stable to remain firm and intact under the feet of the workers. Subgrades for concrete structures or trench bottoms which are otherwise solid, but which become mucky on top due to construction operations, shall be reinforced with graded gravel. The stabilizing material shall be spread and compacted to a depth of not more than 4 inches (100 mm) and shall be compacted as specified for trench backfill. 3-3. Excavation Below Pipe Subgrade. Except where otherwise required, pipe trenches shall be excavated below the underside of the pipe, to provide for the installation of embedment materials, as indicated on the Agency's Standard Bedding Details. 3-4. PIPE EMBEDMENT. Embedment materials both below and above the bottom of the pipe, classes of embedment to be used, and placement and compaction of embedment materials shall conform to the requirements indicated the Agency's Standard Bedding Details. The type of encasement required will be selected by the Engineer based on the type of materials utilized and the anticipated foundation conditions. Embedment material shall contain no cinders, clay lumps, or other material which may cause pipe corrosion. 3-4.02. Embedment for Steel, Pipelines. Pipe embedment for coal tar coated steel pipelines shall either be granular fill completely encapsulated with filter fabric, or graded gravel. 3-4.03. Placement and Compaction. Granular embedment material shall be spread and the surface graded to provide a uniform and continuous support beneath the pipe. It will be permissible to slightly disturb the finished subgrade surface by withdrawal of pipe slings or other lifting tackle. After each pipe has been graded, aligned, and placed in final position on the bedding material, and shoved home, sufficient pipe embedment material shall be deposited and compacted under and around each side'of the pipe and back of the bell or end thereof to hold the pipe in proper position and alignment during subsequent pipe jointing and embedment operations. Embedment material shall be deposited and compacted in a mannner which will not cause significant scratching or abrasion of the pipe coating or damage to the polyethylene protection. Embedment material shall be deposited and compacted uniformly and simul- taneously on each side of the pipe to prevent lateral displacement. Each lift of granular embedment material shall be compacted by either jetting, or by mechanical compaction with suitable vibratory equipment. Jetting of the granular embedment will be allowed in areas where the soils exposed in the trench excavation consist of coarse grained, free draining materials with a minimum sand equivalence of 20. Jetting shall conform to the requirements of the Standard Specifications for Public Works Construction 1997 Edition, Section 306-1.3.3. Mechanical compaction, utilizing vibratory equipment, will be required in areas where the soils exposed in the trench excavation consist of fine grained soils classified as CL, CH, ML, MH, OL, OH and or PT by the Unified Soils Classification System with a sand equivalence of less than 20. Granular embedment in these areas will be vibrated with a mechanical probe type vibrator during placement to ensure that all spaces beneath the pipe are filled. Each lift of embedment material shall be compacted with a platform type vibrating compactor to at least 90 percent relative compaction as determined by ASTM D1557. 3-5. TRENCH BACKFILL. All trench backfill above pipe embedment shall conform to the following requirements. A layer of backfill material not more than 8 inches [200 mm] deep may be placed over concrete arch encasement or concrete reaction blocking after the concrete has reached its initial set, to aid curing. No additional backfill shall be placed over arch encasement or blocking until the concrete has been in place for at least 3 days. 3-5.01. Compacted Backfill. Compacted backfill will be required for the full depth of the trench above the embedment in all locations. At the option of the Contractor, compacted backfill may be (a) suitable job excavated material, or (b) graded gravel, or (c) imported soil, as described below: a. Job Excavated Material. Job excavated material may be used for compacted backfill when the job excavated material is finely divided and free from debris, organic material, cinders, any corrosive material, and stones larger than 3 inches [75 mm] in greatest dimension. No more than 30 percent of the backfill volume shall be larger than 3/4 -inch in greatest dimension. Rocks greater than 1 inch in greatest dimension shall not be placed within 12 inches of pavement subgrade. Masses of moist, stiff clay shall not be used. Job excavated materials LOCKWOOD ENGINEERING CO. 380 W. FOOTHILL BOULEVARD STE. F RIALTO, CALIFORNIA 92376 (909) 875-5015 FAX (909) 875-4567 MARK I DESCRIPTION REVISIONS shall be placed in uniform layers not exceeding 8 inches [200 mm] in uncompacted thickness. Each layer of material shall have the best possible moisture content for satisfactory compaction. The material in each layer shall be wetted or dried as required and thoroughly mixed to ensure uniform moisture content and adequate compaction. The method of compaction and the equipment used shall be appropriate for the material to be compacted and shall not transmit damaging shocks to the pipe. Job excavated material shall be compacted to 95 percent of maximum dry density at a moisture content ranging from -2 to +2 percent relative to the optimum moisture content, as determined by ASTM D1557 for the upper three feet of trench soils underlying pavement. All other trench backfill shall be compacted to 90 percent of the maximum laboratory density per ASTM D1557. b. Graded Gravel. Gravel backfill shall be deposited in uniform layers not exceeding 12 inches [300 mm] in uncompacted thickness. The backfill shall be compacted with a suitable vibratory roller or platform vibrator to at least 90 percent relative density as determined by ASTM D1557. Imported Soils. Imported soils shall be free of all perishable materials and have the following characteristics: (1) less than 30 percent by weight retained in 314 -inch sieve, (2) a minimum of 15 percent by weight passing the #40 sieve, but not greater than 40 percent by weight passing #200 sieve, (3) plasticity index of fines <10 and liquid limit <30, and (4) no particles larger than 3 inches in largest dimension. 3-5.02. Water Densified Compacted Backfill. Compacted backfill may be densified by jetting provided the materials to be jetted and the soils exposed in the trench excavation are coarse grained, free draining materials. Mechanical compaction, utilizing appropriate equipment, will be required in all areas where the soils exposed in the trench excavation consist of fine grained soils classified as CL, CH, ML, MH, OL, OH and or PT by the Unified Soils Classification System with a sand equivalence of less than 20, or where the backfill materials have a sand equivalence of less than 30. Jetting shall be performed in accordance with the Standard Specifications for Public Works Construction, Section 306-1.3 Where jetting is utiilized, the backfill shall be allowed to drain sufficiently until the surface of the backfill is firm and unyielding, prior to the placement of additional backfill. 3-6. STRUCTURE BACKFILL. Structure backfill which will be placed beneath pipes, roads, parking areas, walks, curbs, gutters, or other surface construction or structures shall be deposited in layers not to exceed 8 inches [200 mm] in uncompacted thickness and shall be compacted to at least 95 percent of maximum dry density at a moisture content ranging from -2 to +2 percent relative to the optimum moisture content as determined by ASTM D698. Backfill placed around structures in other areas shall be compacted to the extent necessary to prevent future settlement. Compaction of structure backfill adjacent to structure walls shall be performed with hand operated compaction equipment. The minimum limits of hand compaction shall be within the limits defined by a line which projects upward from the edge of foundation at a one horizontal to one vertical slope. Compaction of structure backfill by inundation with water will not be permitted. No backfill shall be deposited or compacted in water. Wherever a trench is to pass through structure backfill, the structure backfill shall be placed and compacted to an elevation not less than 12 inches [300 mm] above the top of pipe elevation before the trench is excavated. Compacted areas, in each case, shall be adequate to support the item to be constructed or placed thereon. End of Section APPR. I DATE I CITY APPR. I DATE i o.41- 7-.1 e, 4� CIVIL ENGINEER FOR INLAND EMPIRE UTILITY AGENCY b INLAND EMPIRE UTILITIES AGENCY* *A Municipal Water District Date o/, �a fl� LOCATION MAILING ADDRESS 9400 Cherry Avenue, Building A Post Office Box 697 Fontana, California 92335 Rancho Cucamonga, California 91730 Telephone (909) 357-0241 CITY OF FONTANA, CALIFORNIA PUBLIC WORKS DEPARTMENT DRAWN BY: SEWER IMPROVEMENT PLANS SCALE: HORIZ.-1 "=40' DWH USF BE AY, INC. VERT. -l"=4' DESIGNED BY: ETIW V N U E DATED: DWH TWEEN SLOVVE ANTA ANA AVE os/12/o� CHECKED BY: APPR D:. DR. No. SHEET CWLZ&V92f00 5 of 5