Erosion and sediment control plan

MMC - GAMUDA JV MMC Corporation Berhad

Gamuda Berhad

PROPOSED DOUBLE TRACKING RAILWAY PROJECT BETWEEN IPOH - PADANG BESAR

MMC-GAMUDA JV SDN BHD

ENVIRONMENT ASIA SDN BHD


Gamuda Berhad

PROJECT BRIEF Project Activities

The Project will involve the following works: • Construction of new double track along new alignment • Removal of the existing railway track, bridges and materials. • Construction of new concrete bridges over rivers, streams and lakes for the new double track. Construction of new culverts. • Construction of road over head bridges (ROB) to replace present level crossings. • Construction of new stations and depots. • Construction of Bukit Larut tunnel and Bukit Berapit Tunnel. • Fencing and electrification of the tracks.


Gamuda Berhad

Erosion and Sediment Control Plan (ESCP) • EROSION RISK ANALYSIS • EROSION AND SEDIMENT CONTROL MEASURES • MONITORING, SITE INSPECTION AND MAINTENANCE MMC-GAMUDA JV SDN BHD

ENVIRONMENT ASIA SDN BHD

EROSION & SEDIMENT CONTROL MEASURES • Erosion and sedimentation control measures under Best Management Practices (BMPs) – – – – – – – – – –

Phasing of Construction Activities Silt Traps Silt Fences Protection for Cut and Fill Slopes Slope Stabilization of Embankments Drainage Control Protection for Stockpiles Vegetation Buffer Turfing Silt Curtains

EROSION & SEDIMENT CONTROL MEASURES • Silt Trap – to collect and store sediment from areas cleared during construction. – 2 types (dry/wet) and 4 sizes

EROSION & SEDIMENT CONTROL MEASURES Design of Silt Traps Sizing for the Silt Traps (for Sandy Loam-Dry Sediment Basin) Length of Track (m)

Disturbed Area (x25m width) Acre Hectare

<500 500-1000 1000-1500 >1500

3.09 6.18 9.27 12.36

1.25 2.50 3.75 5.00

Silt Trap Size (m) Type Width (W) 12 16 19 22

Length (L) 24 36 40 45

Depth (d) 2.5 2.8 3.0 3.0

A B C D

EROSION & SEDIMENT CONTROL MEASURES

Typical Design of Dry Sediment Basin Silt Trap

EROSION & SEDIMENT CONTROL MEASURES Sizing for the Silt Traps (for Clay Soil-Wet Sediment Basin) Length of Track (m)

Disturbed Area (x25m width) Acre Hectare

<500 500-1000 1000-1500 >1500

3.09 6.18 9.27 12.36

1.25 2.50 3.75 5.00

Silt Trap Size (m) Type Width (W) 12 16 19 22

Length Depth (L) (d) 24 2.5 36 2.8 40 3.0 45 3.0

A B C D

EROSION & SEDIMENT CONTROL MEASURES

Sizing for the Silt Traps (for Clay Soil-Wet Sediment Basin)

EROSION & SEDIMENT CONTROL MEASURES • Silt Fences – to intercept drainage and surface flow prior to entering nearby waterways or rivers. – varying lengths of 50-100m depending on site conditions and requirements.

Example of Silt Fence

Typical Silt Fence Design

EROSION & SEDIMENT CONTROL MEASURES • Protection for Cut and Fill Slopes – Slopes above the railway platform will be cut according to the design specified by the geo-technical engineer and based on soil parameters to minimize erosion. – temporary embankment should be well compacted to ensure that the soil particles are not readily eroded by runoff. – The excess earth from cut activity, if any, should be stored temporarily at designated stockpile area. – Fill areas should be compacted and graded so the runoff diverts into the temporary drains, which leads to the silt traps. – The fill material should be compacted properly in order to prevent excessive soil wash down during heavy rains. – Protection of borrow pit areas similar to cut and fill slopes. – All cut and filled slopes will be turfed.

EROSION & SEDIMENT CONTROL MEASURES • Slope Stabilization of Embankment – Proposed methods : piled embankments and stone columns • Piled embankments - for ground improvement works and slope stabilization, mostly located at the slope area prior and after bridges. • Stone columns - columns of compacted granular material installed in soil for the purpose of improving the soil characteristics

EROSION & SEDIMENT CONTROL MEASURES • Drainage Control – Before commencement of earthworks, temporary drains to be constructed to channel surface runoff for control of sediment discharge.

– Temporary drains should be directed into silt traps. Sizing of Earth Drains Earth Drain Earth Drain Size (m) Slope Length (m) 1:2 Width Depth <500 1.0 0.5 500 – 1000 1.0 1.0 1000 – 1500 1.5 1.0 >1500 1.5 1.5

Depth

Width

EROSION & SEDIMENT CONTROL MEASURES • Protection for Stockpiles – All excavated material from earthwork activities must be deposited in a designated depository area. – Unsuitable material be temporarily stockpiled prior to being transported to designated dumpsites. – Dumpsites / stockpiles should be located away from surface runoff flow paths and not adjacent to waterways. – Stockpiles should be compacted, covered with plastic / geotextile sheets that should be embedded into the top part of the stockpile or weighted down with heavy rocks. – On sloping ground, silt fences and earth banks recommended.

Stockpile Protection

EROSION & SEDIMENT CONTROL MEASURES • Vegetation Buffer – Site clearing shall be limited to work areas of the alignment for each stage of work. – Vegetation cover should not be cleared until earthworks are ready to begin. – Existing vegetation along the riverbanks should be retained where possible as a natural buffer strip for the purpose of reducing runoff and increasing settling and infiltration.

EROSION & SEDIMENT CONTROL MEASURES • Turfing – All cut and fill slopes will be turfed. – main turfing carried out at sloping areas of the viaduct abutments. – immediately upon completion of earthworks at exposed areas to reduce runoff velocity and to minimise erosion along contors. – Vegetation that is fast growing and hardy is recommended.

– Spot turfing and close turfing techniques are recommended for entirely bare areas.

EROSION & SEDIMENT CONTROL MEASURES • Silt Curtain

– To be used at areas of land reclamation works. – Constructed encircling the fill area to prevent excessive dispersal of sediments during the fill process.

Example of silt curtain

Reclamation Works Methodology

EROSION & SEDIMENT CONTROL MEASURES • Workers Camp, Site Offices, Casting Yard, Storage Areas and Workshops.

– Temporary internal drainage shall be constructed – Channel runoff effectively. – All runoff should be channeled into a silt trap prior to discharge out of the site. – The drainage system and the silt trap should be regularly inspected and maintained especially after heavy rainfall.

Wash trough

Silt Trap

Oil Interceptor

Legend Existing drainage Temporary drainage

Wash trough

Typical design for Workshop / Storage Area

Typical Design for Wash Trough

MONITORING, INSPECTION MONITORING, SITE INSPECTION ANDSITE MAINTENANCE AND MAINTENANCE

Monitoring • Total Suspended Solid (TSS) • Contractor Activity BMP • Sediment and Erosion Control BMPs

Monitoring

MONITORING, SITE INSPECTION AND MAINTENANCE

I) Total Suspended Solid (TSS) Monitoring • Monthly TSS Monitoring shall be carried out at all discharge outlets of the silt traps during both the earthworks and construction work. • The water discharged from the silt traps should not contain suspended solid load exceeding 100 mg/l as stipulated by the DOE’s EIA Condition of Approval No. 21.

Monitoring


II) Contractor activity BMP Monitoring  Inspect for evidence of spills requiring cleaning up activities.  Verify adequate supplies of spill containment and cleanup materials (e.g. oil absorbent rolls/boom).  Examine the integrity of containment structures.  Verify employee education programs for the various activities.  Note the location of activity (e.g. outdoor vs. indoor, concrete vs grass).  Verify adequacy to provision of waste receptacles.  Verify waste disposal practices (e.g. recycle vs. hazardous waste bins).

Monitoring


III) Sediment and Erosion Control BMPs • Monitor effectiveness of Sediment and Erosion Control BMPs. • Sediment and Erosion Control BMPs may be ineffective if: – Silt is present outside the control area. – Structural controls are breached or fail under storm events of minor intensity. – Rills and gullies are present in stabilized slopes. – Silt buildup downstream of site. – Controls are not maintained in accordance with design guidelines. • Any change in drainage patterns and the extent of the change to be addressed accordingly.


Site Inspection • Regular site inspection to ensure the ESCP is always operating in accordance with it’s design intent. • The results of the inspection and assessment will be recorded in writing. • Frequency of Inspections: – After any rain or storm event with substantial runoff (silt trap and silt fences). – Daily when grass cover is less than 100% on vegetated areas. – Weekly as a matter of site routine for all site practices. – Before site closure.

Site Inspection


Overall site inspection activities: • Inspection of catch drains, earth banks, table drains, and slope drains. Initiate cleaning if required. • Removal of any stockpile material or sediment that has encroached within 2 m distance to surface drain. • Restoration of low spots in earth banks and diversion drains to their original height and compact. • Where necessary, construction of extra earth drains and/or diversion drains that help separate on-site silted waters from other rain water runoff.

Site Inspection


Overall site inspection activities: • Install any new erosion and sediment control measures that have become necessary since previous inspections due to severe storms or progress / changes in the site’s development. • Check to ensure that all earth banks, diversion drains, and waterways are operating within the safe limits for the surface conditions by observing any scouring evidence. • Ensure that any construction work at site since previous inspection has not diverted sediment and water away from planned runoff channels. • Inspect structural integrity of silt traps and silt fences.


Maintenance Program • • • •

Silt trap maintenance Silt fence maintenance Maintenance of vegetated surfaces Repairing of damaged and breached structures

Maintenance


I) Silt trap maintenance • When filled with sediment greater than 2/3’s of the depth, de-silting works to remove the accumulated sediment must be carried out immediately. • The sediment should be removed for dumping at the approved dump site. • All breaches of the gabion / bund wall must be repaired. • Vegetative debris or construction waste material washed into the silt trap must be removed immediately to prevent blockage and damage to the bund wall or outlet pipe/riser.

Breach in bund wall

Blocked riser

Maintenance


II) Silt fence maintenance • Where the silt fence is being back-filled with accumulated sediment, these should be removed manually. • The sediment should be removed for dumping at the approved dumpsite. • All breaches of the silt fence must be repaired or replaced. • Vegetative debris or construction waste material washed onto the silt fence must be removed to prevent any damage to the silt fence.

Maintenance


III) Maintenance of vegetated slopes      

Seek professional agricultural advice where necessary Additional irrigation (watering) Application of fertilizers Reseeding Mulching Weed control

IV) Repairing of Damaged and Breached Structures  Repair, re-pin, or replace torn detached and damaged liners, biodegradable blankets, geo-fabric.  Fill and compact low spots in earth banks and diversion drains where vehicles or other factors have reduced the design height and stability.  Repair (re-stabilize) any eroded areas.

MONITORING, SITE INSPECTION AND MAINTENANCE Plan Review and Modifications – The ESCP should be reviewed and modified if any changes significantly affect it were to occur such as: • • • • •

Changes to the Project schedule Staging area modifications Off-site drainage impacts Repeated failures of designed controls. Properly installed systems are ineffective in preventing silt transport off the site. This may be due to unforeseen site conditions or construction techniques. • A new, relocated activity that could result in the discharge of significant amounts of sediment.

– Changes should be identified accordingly, made known and the ESCP revised accordingly. – During the preparation and review of the modified ESCP, construction work to continue with temporary modifications to the erosion and sediment control BMPs.

Erosion and sediment control plan

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