In this issue:Case History Mitigation to Landfill Gas Hazard by Geomembrane, Simple & EffectiveNew Product / Application• A Brand New Usage of

Geotextile - Blasting• Geotextile Container in

Another UseTechnical NoteHDPE Fabrication for Unusual PurposesOpinion ColumnTechnique in Installing Concrete Protection LiningFor Your Information • Sharing with the Young• A Visit to Maccaferri

Philippines• Inventory Available for

Immediate DeliveryReader’s Response

Mitigation to Landfill Gas Hazard by

Geomembrane, Simple & Effective

Dec 2015. Issue No.17

Any development within landfill gas consultation zone poses potential risk frommethane and carbon dioxide. The gas can enter into confined space such as plantroom, lift pit, underground fuel tank etc., through passage within the soil in thefoundation. This can be destructive. Therefore a standard practice to prevent gasingression through underground soil into building by blocking its migration ordiverting it to an external vent is in place. High density polyethylene geomembrane(HDPE), an impermeable membrane, is often used as the barrier to isolate theconfined area so that any gas built up can be dissipated elsewhere.HDPE is usually installed below ground floor slab, in between tie beam, fixed ontopile cap, enclosing underground structure and as a vertical cut off barrier along thesite boundary. HDPE follows the EPD guideline of low permeability of 10-12m/s witha 30 year design life span. A hazard gas assessment usually prepared by theenvironmental specialist would determine the barrier requirement and where itshould be deployed.HDPE has a thickness of usually 1 – 2 mm and can be sized and seamed to fitspecific area. Practical termination details, proprietary welding techniques andtesting would ensure the integrity of impermeability. A protective geotextile isoften applied to cushion against construction damage.

ASD contract SS C506 School for Social Development,

Choi Hing Road by Jordan Valley Landfill, Fook Lee

Construction Co Ltd, 4,000m2 (Aug 2015)

Multimedia Production Distribution Center, next to TKO Landfill, China Resources Construction Co Ltd, 6,800m2 (Nov 2015)

There are a few ongoing projects at the moment where we are installing and testing gas barrier. Many werecompleted and warrant back from the mid 90’s. Reach Stanley at Stanley@g-and-e.com for any details.

High Tier Data Center, adjacent to TKO Landfill,

Sanfield (Management) Ltd, 500m2 (Feb 2015)

G and E Times

2.

Technical Note

Dec 2015. Issue No.17

HDPE Fabrication for Unusual Purposes

Tube made by geotextile

While HDPE geomembrane welding is common in landfill lining system, large scalewater containment, gas barrier and waterproofing, the unique welding techniquecan be applied in other field of HDPE fabrication. Extrusion welding employs moltenHDPE resin to be applied across two heated HDPE surfaces brought into contactunder specific pressure, when the extrudate cools down along the contact, the twosurfaces and the extrudate are fused together to form a single integral unit,resembling a homogeneous component.

New Product / Application

A Brand New Usage of Geotextile - BlastingA fabric is sought as dust cover and containment of small flyingobjects for controlled rock blasting. It is placed over rubber tire andis ballast by steel wire mesh over the area to be blasted. Thematerial should be strong and flexible to confine flying rock, heatresistant, fire extinguishable and inflammable for safety reason, andshould be reasonably economical to be replaced potentially forevery blast.Typical light weight non-woven geotextile was tried but was burnt Blasting at XRL excavation

through. A 1,350 gsm non-woven was too heavy to maneuver, hence not considered. Size of fire blanket was toosmall to be practical. A woven high strength 110 x 110 kN/m 460 gsm geotextile performed but catching fire wasto a lesser extent. While addition of fire retardant compound to geotextile is doable, special production costbecomes exorbitant. By limiting to a small area per blast, the high strength woven geotextile was eventuallyadopted, with a small manageable fire which did not spread and extinguished quickly. It cannot be concluded asan engineered solution, but a practical undertaking. To find out more about this, contact Gary at nangary1@i-cable.com.

Geotextile Container in Another Use – Repair WorkRepair work to an operating submerged pipe needs diversion, bypass andstoppage of flow. A geotextile container can be fabricated into a tube sothat it can be filled up to plug the pipe, downstream can then be kepttemporarily dry. This was the idea at XRL where a 1.2m diameter x 3mlong geotextile tube was used. A high strength geotextile was stitchedinto the shape of a tube with infilling port on top. The unit was placedmanually into the pipe, through a cut opening. Slurry material waspumped into the tube. The pressure created by the expansion of the tubepresses against the internal profile and block any flow. It was then cutopened to re-allow flow. To find out more about this, contact Gary atnangary1@i-cable.com.

Extrusion welding to join

HDPE pipe

We saw HDPE pipes pieces that can be welded toform Tee, multi cross, lengthy extension, in differentdiameter, at different shape, at acute angle and invarious thicknesses. Puddle and blind end fabricationfollows similar procedure, repair is not beyondpossibility. Even the pipe can also be jointed to HDPE

chamber or tie into HDPE membrane. Joint integritycan be verified by electronical or hydraulically testing.Get in touch with Stanley at stanley@g-and-e.com forfurther information.

HDPE Tee junction is formed

by extrusion welding

Electric extrusion welder

G and E Times

3.

Opinion Column

Technique in Installing Concrete Protection Lining

Dec 2015. Issue No.17

Concrete structure can deteriorate extensively and quickly when exposed constantly to sewage gas. The use ofprotective lining that can be cast into the concrete has been well recognized, adopted in a great many projects.Effectiveness falls on the design detail and proper installation.Concrete protection liner has to be attached to formwork in panels pre-assembled prior to placing reinforcement,formwork is then removed after concrete curing and the lining has to be subsequently jointed and tested toensure a uniform homogeneous coverage over the structure. Special attention is necessary in every stage of work.Contractors are often not aware of the attentiveness, details are overlooked and often disregarded withinsufficient budget or pushy program. Performance can be undermined and quality can be compromised. Clearlystated work procedures and mock up are beneficial.The design of the structure is sometimes quite complex to allow simple application of such liner, not to mentionthe liner has T-ribs or studs. While working over corners, recess, pipe penetration, fixture and awkward shapecan follow standard details, coordination amongst different trade such as attachment to formwork, erection offormwork, placing reinforcement bar, concreting, removal of formwork can become unmanageable. It is wise todesign with less complicated structure to begin with. Contact Stanley at Stanley@g-and-e.com for insights andideas.

For Your Information

We are very much dedicated to sharing our knowledge with the youngergeneration, allowing them to develop and prosper the way we werebrought up. Site visit on hand experience is highly treasured. We saw agroup of Hong Kong University students navigated steep slope on abeautiful Saturday morning, to appreciate the application of flexiblebarrier and gabion buttress wall on natural terrain debris flow mitigation.Thanks to the initiation of CEDD, the consultant engineer and the maincontractor, we were able to contribute in some of their educationalprograms. Contact Nannette at Nannette@g-and-e.com for experiencesharing programs.

HKU students at Luard road Site Visit

Sharing with the Young

Pressure test of HDPE extrusion welding integrity - capping over a cut opening – a successful trial for the repair method

Above and right: New construction utilizes PVC

protection lining keyed into concrete structure

Concrete deteriorates without protection

lining after exposure to hydrogen sulfide

G and E Times

4.

Reader’s Response

Let us hear from you. Write to us at newsletter@g-and-e.com

Disclaimer The materials contained in this newsletter are provided for general information purposes only and do not constitute legal or other professional advice.

G and E Company Limited14th Floor, Kiu Yin Commercial Building, 361-363 Lockhart Road, Wanchai, Hong Kong

Tel: 2570 0103 Fax: 2570 0089 e-mail: wing@g-and-e.com website: www.g-and-e.com

Tell a ColleagueWant your colleague to receive G and E Times also, click here.

Unsubscribe If you do not wish to receive G and E Times in the future, please reply to this e-mail stating “Unsubscribe” in the subject.

For Your Information

Inventory for Immediate Delivery倉有，可隨時送貨

CEDD, HyD, DSD and consultant approval, extensive reference,

Dec 2015. Issue No.17

Green PVC coated

wire mesh,

Indonesia印尼綠色包膠護坡鐵網

Miradrain 5000 and 6000 equivalent

等同Miradrain5000和6000Biodegradable erosion mat

可生物分解的防侵蝕護墊

HDPE membrane,

Thailand 泰國For leakage collection

用作为洩漏收集

Polyamide erosion control mat

防侵蝕控制墊，最新的聚酰胺材料

Maccaferri

Macmat, Italy 意大利

Maccaferri P/6/2.2 wire mesh

Maccaferri is now expanding their rockfall barrier production in Asia. Themanufacturing facility in Philippines rolls out its first unit in December. Ourengineers took a visit to the plant in the inauguration month to get familiar withthe production, quality control, assemble of components and packaging. With astronger quality assurance program, an experienced expatriate managementteam and efficient logistics in Asia, we are sure that the new era of flexiblebarrier fabrication will be more competitive and friendly to users.

A Visit to Maccaferri Philippines

Maccaferri Philippines team

with G and E engineers

excellent prices土木工程拓展署，路政署，渠務署和顧問公司的認可，充分的批函，超值价格

ABG Deckdrain, UK 英國 CCM 700, India 印度