JAPANAN METERING STATION PROJECT (CP-17)

PT PERUSAHAAN GAS NEGARA (Persero)

CONTRACT NO. :

PP JOINT OPERATIONDOC. NO. :

CONTRACT PACKAGE NO. 17 :PENGADAAN JAPANAN METERING STATION PROJECT (CP-17)

DESIGN BASIS MANUALSOIL EROSION MEASURE CONTROL

018/08/2014ISSUED FOR BID

REV.DATEPAGED E S C R I P T I O NPREPRDCHKDAPPDCHKDAPPD

CONTRACTORPMCPGN

REVISION PAGE

REV.DATEPAGESDESCRIPTION

A26/01/2014ALLIssued for Bid

DESIGN BASIS MANUAL

SOIL EROSION CONTROL MEASURES

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 DEFINITION

3.0 CODES, STANDARDS AND SPECIFICATIONS

4.0 GENERAL

5.0 DITCH BREAKERS

6.0 DIVERSION DIKES

7.0 TEMPORARY WATERWAY CROSSINGS

8.0 TEMPORARY LINING

9.0 RIP-RAP

10.0 SEDIMENT TRAP

1. INTRODUCTION

This Design Basis covers the manual for the construction of soil erosion control associated with Contract Package No. 17 (CP-17): EPC for Pengadaan Japanan Metering Station.

2. DEFINITION

For the definition of term appearing with this documents that are not given specifically herein, reference should be made to the Conditions of Contract and Doc. No. CP17-PGN-3514-xxx Rev.0 Scope of Work.

In addition, the following definition shall apply:

THIRD PARTY-Inspection Company approved to act on behalf of MIGAS

3. CODES, STANDARDS AND SPECIFICATION

This design basis manual was prepared based on the following references:

3.1 Soil Mechanics in Engineering Practice.Second Edition Karl TerzaghiRalph B. Peck

3.2 Petunjuk Perencanaan Penanggulangan Longsoran. SKBI 2.3.06.1987UDC : 624.13 (083.7)Departemen Pekerjaan Umum

3.3 Biotechnical Slope Protection and Erosion Control. Donald H. Gray Andrew T. Leiser3.4 O.S.H.A (Occupational Safety and Health Act regulations)Construction Standard for Excavations(29 CFR PART 1926.650.652)Sub part PPipe Line Construction Association

4. GENERAL

Considerations shall be made during design to prevent soil erosion as a result of the development of pipeline facilities. Permanent and temporary control measures shall be designed and implemented which reduce the impact of the erosive forces of increased storm runoff and soil disturbances from construction activities. The following principles should be considered for effective erosion control:

Minimize the extent of disturbed areas - Construction activities should be sequenced to minimize the amount of area disturbed at one time. Divert up slope runoff - Overland flow from upslope areas should be diverted around disturbed areas to minimize the amount of erosion generating runoff from the disturbed area.Keep runoff velocities low - Clearing vegetation reduces infiltration and surface roughness, resulting in increased runoff volumes and velocities. Measures that break slopes and diffuse flows or divert flows to stabilized outlets can reduce problems associated with concentrated flows and velocities.Stabilize disturbed areas - Temporary or permanent stabilization of exposed soils should be provided as soon as practicable after grading or other earthwork activities has ceased. Stabilization practices may include seeding, mulching, geotextiles, and stone rip-rap.

Accumulation of water on pipeline route shall be prevented, and natural flow shall not be interrupted, during construction time. All natural flow shall be reinstate to its original condition after construction is completed. Control measures shall be designed and drawings prepared showing the location of proposed temporary and permanent erosion control measures to be installed. The drawings shall be prepared in accordance with the Environmental Impact Assessment (EIA) document for this project and the standards and regulations Applied. The following control measures shall be utilized as required to provide protection against soil erosion. Specific situations or problems may require additional measures to be considered.

Location of permanent erosion protection shall be surveyed in advance. Resulting in a list of locations and type of erosion protection installed in each area. The list shall be prepared for PGN review and approval.

Installations of each permanent erosion controller shall be performed immediately after back filling of the related section is completed.

CONTRACTOR shall provide all recovery for every damage caused by construction.

5. DITCH BREAKERS

5. 1 Description

A barrier placed around the pipeline consisting of dry soil filled burlap bags or urethane foam to serve as a water barrier by obstructing flow or seepage along a pipeline and thereby controlling erosion of the ditch backfill material.

5. 2 Design Criteria

Ditch breakers shall be installed in the pipeline ditch at the spacing indicated in Table 1 as the minimum requirements. Additional location of the breakers may be required as specified in the field by PGN.

TABLE 1SPACING FOR DITCH BREAKERS

Slope of pipeline ditch

35%

Maximum distance between plugsN/A150m90m60m30m15m

5. 3 Location

Ditch breakers location shall be specified by CONTRACTORs Field Engineer and PGN approval. Locations shall be established prior to commencement of trenching activity.

5. 4 Material

Ditch breakers shall consist of burlap bags filled with dry sandy soil other than topsoil. The CONTRACTOR may substitute urethane foam for burlap bags with PGNs approval.

The CONTRACTOR shall submit the design to PGN for approval.

5. 5 Installation

Permanent and temporary control measures shall be installed to reduce the impact of the erosive forces of increased storm runoff and soil disturbances from construction activity.

The installation shall be completed prior to back filling.

6. DIVERSION DIKES

6. 1 Description

A dike to be constructed across a slope of a disturbed area to redirect sheet flow or concentrated flow runoff around disturbed areas toward a stabilized outlet where water can be discharged without adversely impacting the receiving area or channel. The dike can also serve as an interceptor dike to shorten the length of exposed slopes by intercepting runoff and diverting it toward a stabilized outlet.

6. 2 Condition Where This Practice AppliesOn slope of disturbed areas where erosion is likely to occur and where runoff protection is needed to prevent erosion on sloping right-of-ways or other long, narrow, sloping areas - generally less than 30 meters in width.Design Criteria

Capacity: the capacity of the dike / swale shall be desgined tocarry the peak runoff from at least the 2 years, 24-hour frequency storm with a freeboard not less than 100 mm. The drainage area shall not exceed two (2) hectares.

Top Width : 600 mm minimum

Height: 500 mmm measured from bottom of swale

Side Slope : 2 H : 1 V or flatter

Grade : Positive grade not to exceed 2 percent

6. 3 LocationAlong right-of-way slopes, interceptor dikes shall be spaced in accordance with Table 2 as the minimum requirements. Additional location of the dikes may be required as specified in the field by PGN.

TABLE 2SPACING FOR INTERCEPTOR DIKES

Slope of area above interceptor

10%

Maximum distance between interceptors

150m90m60m30m

On steep slopes, greater than 30%, interceptor dikes may be installed at the top and base of the slope only.

Diversion dikes location shall be specified by CONTRACTORs Field Engineer with PGN approval. Locations shall be established prior to commencement of trenching activity.

6. 4 Material

Fill material of dikes is using local material or soil excavation of diversion ditch. Dikes shall be compacted using earth moving equipment and have positive drainage to an outlet.

6. 5 InstallationPermanent and temporary control measures shall be installed to reduce the impact of the erosive forces of increased storm run off and soil disturbances from construction activity.Each diversion dike or interceptor shall have an adequate outlet capable of diverting runoff to a location where the discharge will not cause erosion or adverse impacts.Diversion dikes shall be stabilized either by sodding or seeding and mulching within 7 days of final grading.The installation shall be completed prior to back filling.

7. TEMPORARY WATERWAY CROSSING

7. 1 Description

A temporary structure installed across a stream or waterway for short-term use by construction vehicles or heavy equipment to move from one side to the other without damaging the streambed, or channel, or depositing sediment into the waterway.

7. 2 Conditions Where Practice Applies

Where heavy equipment must be moved from one side of the waterway to another, or where light-duty construction vehicles must cross the waterway channel frequently for a short period of time.

7. 3 Design Criteria

The travel way for all structures shall be a minimum of 5 meters wide.

Culvert design shall meet local requirements for accommodating fish and marine life passage.

The culvert structure shall be designed to pass the bankfull flow or peak flow from a 2-year recurrence-interval storm, whichever is less, without over-topping. Measures shall be taken to ensure that no erosion will result from the 10-year recurrence interval peak storm. Over topping is allowed during the 10 year recurrence-interval peak storm if contained within the limits of the channel banks.

7. 4 Location

The design flow velocity at the culvert outlet of the crossing structure shall not cause erosion of the receiving channel.If the slope above the stream banks is greater than 2 percent, a diversion dike shall be placed above the stream banks to divert surface runoff away from the disturbed channel section and discharge to a stable outlet. A temporary culvert shall be designed to support the maximum expected load. The minimum culvert size shall be 12-inches. The maximum culvert length is 12 meters.

7. 5 Materials

Culverts shall be steel pipe, reinforced concrete pipe, or corrugated steel.

Aggregate fill shall be clean stone with a minimum size 40 mm - 90 mm and shall be used on the top 10 cm; otherwise, stone shall have an average diameter of 10 cm.

Geotextile fabric shall meet or exceed the following requirements:

Tensile strength90 kg Trapezoid35 kg Puncture strength45 kg Maximum elongation at failure75% Minimum lap length60 cm Permeability of fabric must be greater than permeability of soil, and Stone placement drop height shall be less than 1 meter.7. 6 Installation

Fords may be constructed at watercourses where bank height is less than 1.5 meters and flow is intermittent. Approach sections shall be graded to a maximum 5H: 1V slope. Stream bed shall be stabilized with clean stone.

8. TEMPORARY LINING

8. 1 Description

A fabric matrix blanket consisting of natural fibers placed on a seedbed of a channel or steep slope to prevent erosion by providing a protective cover and stabilization during the establishment period of vegetation.

8. 2 Conditions Where Practicable

Waterways where channel velocity exceeds maximum velocities listed in Table 3.

On slopes of 3H: 1V or greater where erosion hazard is high and vegetation is likely to be slow to establish adequate protective cover.

TABLE 3

Soil Material

Sandy LoamAlluvial Silt*Stiff Clay

Velocity (meters/second)

0.751.001.50

* Non colloidal

8. 3 Design Criteria

Channel lining selection shall be based on the Permissible Shear Stress method**

Td= x d x s

Where: Td = Maximum Shear Stress on channel lining(kg/sq m) = Unit weight of water (9.8 kN/cu m)d =Maximum flow depth in center of channel (meters)s = Channel slope gradient (m/m)

The selected lining must have a permissible shear stress greater than the maximum calculated shear stress. If a lining is not available which has a permissible shear stress greater than the maximum calculated, then stone rip-rap may be required.

**Developed by U.S. Federal Highway Administration - Hydraulic Engineering Circular #15, 1988, "Design of Roadside Channels with Flexible Linings".8. 4 Location

Temporary Lining location shall be specified by CONTRACTORs Field Engineer and with PGN approval. Locations shall be established prior to commence trenching activity.

8. 5 Material

Fabric shall be straw, coconut or wood fibers sewn together with a biodegradable netting, or woven jute matting and shall be a minimum of 1.25 meters in width.

Anchors shall be No. 11 gauge wire staples or heavier, 150 mm to 250 mm in length.

Placement and installation shall be in accordance with manufacturer's specifications.

8. 6 Installation

Permanent and temporary control measures shall be installed to reduce the impact of the erosive forces of increased storm runoff and soil disturbances from construction activity. The installation of control measures shall comply with standard specification.

9. RIP-RAP9. 1 Description

A layer of crushed concrete, rock, or stone placed over an erodible soil surface to prevent erosion by providing a permanent protective cover.

9. 2 Conditions Where Practicable

Proposed waterways (roadside ditches, swales) where soil conditions, vegetative cover, and water velocity are such that erosion may occur under the design flow conditions.Disturbed waterways (stream banks) where vegetative lining stabilization is not adequate for protection against erosion.

9. 3 Design CriteriaRip-rap lining thickness shall be 1.5 times the maximum stone size and composed of a well graded mixture, but most of the stone (50%) should be of the size indicated by the curve in Figure 1 and based on maximum channel velocity. The smaller pieces shall not exceed 15% of total weight.

9. 4 Location

Rip-rap location shall be specified by CONTRACTORs Field Engineer and with PGN approval. Locations shall be established prior to commence trenching activity.

9. 5 InstallationRip-rap shall be placed on geotextile fabric or bedding of graded filter stone. Placement operation shall ensure a well graded uniform arrangement of stone. Stone placement drop height shall be 1 meter or less. Stone placement drop height shall be 30 cm or less for stone sizes up to 45 cm. For larger stones set in place at 0 drop height.

FIGURE1

9. 6 Material

9.6.1 Aggregate fill

Rip-rap shall consist of a well graded mixture composed primarily of larger stone, but with a sufficient mixture of smaller sizes to fill the voids. Rock or stone used for rip-rap shall be clean, durable and insoluble in water, having a minimum specific gravity of 2.5.

9.6.2 Geotextile fabrics shall meet or exceed the following requirements:

Geotextile fabrics shall meet or exceed the following requirements: Tensile strength115 kg Trapezoid tear40 kg Puncture strength65 kg Maximum elongation at failure30% Minimum lap length shall be60 cm Permeability of fabric must be greater than permeability of soil.

See Drawing No. DW-024-S-008-A3 (Soil Erosion Control Measures Rip-Rap)

10. SEDIMENT TRAP

10.1 Description

A temporary device formed by excavation and/or embankment to intercept sediment laden runoff and trap the sediment laden runoff and trap the sediment to prevent sedimentation in waterways or on adjacent property. 10.2 Conditions where Practice Applies

Construction sites with less than 6 hectares of land disturbance. Areas greater than 6 hectares may require more than one sediment trap.

10.3 MaterialGeotextile fabricClean stone

Design Criteria

Drainage area:The contributing drainage area shall not exceed 6 hectares.

Trap size:The volume of the sediment trap as measured at 500 mm below the elevation of the crest of the outlet shall be at least 126 cubic meters per hectare.

Embankment:Embankments shall not exceed 1.5 meters in height as measured at the low point of the original ground along the centerline of the embankment. The embankment shall have a minimum top width of 1.2 meters.

Side slopes:Fill slopes shall be 2H: 1V or flatter; cut slopes 1H : 1V or flatter.

Outlet:The sediment trap must out fall onto stabilized ground, into a waterway or stabilized channel.

The outlet shall be designed, constructed and maintained in such a manner that sediment does not leave the trap and that erosion at or below the outlet does not occur.

The minimum weir length for the outlet structure shall be as indicated in Table 4.

Trap Cleanout:Sediment shall be removed and the trap restored to the original dimensions when the sediment has accumulated to one-half of the design depth of the trap.

TABLE 4RIP-RAP OUTLET WEIR LENGTH

Drainage Area(hectares)Depth of ChannelmmLength of Weir(meters)

1.05001.8

2.05003.7

3.05004.9

4.06003.7

5.06004.6

6.06005.5

10.4 Location

Sediment Trap location shall be specified by CONTRACTORs Field Engineer with PGN approval. Locations shall be established prior to commence of trenching activity.

10.5 Installation

Area under embankment shall be cleared, grubbed and stripped of any vegetation and root mat. The pool area shall cleared. Embankment shall be constructed with suitable fill material in 200-mm lifts and compacted by traversing equipment over each lift.

Embankment shall have a maximum height of 1.5 meters and all fill slopes shall be 2H : 1V or flatter and cut slopes 1H : 1V or flatter. The elevation of any dike directing water to the trap shall be equal to or exceed the height of the embankment.

Geotextile fabric shall be placed over the bottom and sides of the outlet channel prior to placement of stone. Sections of the geotextile fabric shall overlap at least 50 cm with section nearest the entrance placed on top. Fabric shall be embedded at least 15 cm into existing ground at entrance of outlet channel.

Sediment shall be removed and trap restored to its original dimensions when the sediment has accumulated to the design depth of the trap. Removed sediment has shall be deposited in a suitable area, compacted and graded.

PPJOSoil Erosion Measure ControlPage 15 of 15