APLICATION TO TECHNIQUES

APPLICATION OF GEOMEMBRANE

1. Equipment

1.1. Transportation and storage at site
Geomembrane reels have to be packed and loaded properly not to give any damage. They have to be stored according to be protected from being punctured, from dirt, oil, water, moisture, mud, wear, excessive heat and other

2. Soil works

2.1 General
Before the application, the top 15 cm. of the soil must be compacted to 95 % . The weak or loose parts which couldn't be compacted adequately, should be removed and replaced by proper material to fit the criteria. All the surface to be covered should be smooth and sharp things, ruble, organic material etc. should be kept away. Water and excessive humidity should be avoided.

2.2. Anchorage ditch
Anchorage ditches should be dug according to the application projects before the geomembrane is laid. Giving the edges of the ditches a round shape, sharp curves should be avoided on the connection points where the geomembrane meets the ditch.

3. Application method

3.1. The geomembrane should be protected from any equipment or tool while carrying or using them, or for any reason.

3.2. Smoking and shoes harmful to geomembrane shouldn't be allowed for the workers on the geomembrane.

3.3. The method used to open the rolls shouldn't cause any scratches or undulation on the surface of the geomembrane and shouldn't damage the ground or geotextile laid under it.

3.4. Adequate weights (sand bags or equivalent) should be put on the edges of geomembrane appropriately not to allow the wind blow it up. (When the wind is stronger these weights may be continuous all along the edges).

3.5. Direct contact with the geomembrane should be kept mininmum. For example the parts which must be used for walking should be protected by means of additional membrane, geotextile or other suitable material.

3.6. Weather conditions
Geomembrane should be laid when the weather is between 0 - 40 degrees. Welding shouldn't start during rain or early in the morning when humidity is high.

4. Welding at site
Approved welding methods are fusion or extrusion welding with automatic machines. Weldings should be done as paralel to the slope as possible. Perpendicular weldings should be avoided, site weldings should be minimum at the corners and parts with geometric shapes. "T" weldings at the bottom shouldn't be closer than 1.5 m. to the slope bank. Weldings should be organized as to create minimum undulation and "fishmouth".

4.1 Welding overlapping Geomembrane plates should be overlapped minimum 10 cm for fusion and 7.5 cm for extrusion welding.

4.2 Welding equipments and accessoriesFusion (hot shoe) and extrusion welding machines are approved for site weldings and equipments below should be kept ready :

1. Fusion (hot shoe) welding machine
2. Extrusion welding machine
3. High speed grinder
4. Hot air blower
5. Vacuum test eqoipments
6. Site tensiometer for peeling and slipping tests and equipments to cut test sample.
7. Equipments for air pressure test
8. Equipments to open the reels
9. Necessary electric cabels and other tools

4.3 Test weldingsSite test weldings should be done to check the suitability of welding conditions and equipments. Test weldings should be repeated for all the welding equipments used during the day, at the beginning of each welding period and after major changes in weather conditions. All the test weldings must be at the site where the welding will be done. The length of test welding must be 2 m. for fusion welding and 1 m. for extrusion welding. 1 inch wide test samples must be cut from the test welding and must be tested for peeling and slipping by using tensiometer.

1. Welding slip test samples will be 1 inch wide, and clamp width will be 4 inches + the width of the welding. Welding must be just in the middle of two clamps and test speed must be 2 inches per minute.
2. Both slipping and peeling tests must be done on 5 similar samples each. At least 4 out of 5 samples must be pozitive after tests. Rupture on the welding for both methods is considered as Non-FTB.
3. Approved welding methods are fusion (hot shoe) and extrusion weldings.
4. Welding rods used for extrusion must be HDPE and physical properties must be the same as of the resin used for HDPE geomembrane production.

Minimum welding values for the HDPE geomembrane

Welding	Test	Minimum Value
Test	Method	1.0 mm	1.5 mm	2.0 mm	2.5 mm
Slipping resistanceppi (N/cm)	ASTM D 4437	87 (152)	131 (229)	175 (306)	218 (382)
Peeling resistanceppi (N/cm)	ASTM D 4437	57 (100)&FTB	86 (150)& FTB	114 (200)& FTB	143 (250)& FTB

4.4 Tests of Site weldings
Al the test tools and equipments should be kept on the site and ready for test.

4.4.1 Vacuum test Vacuum test or spark test is applied for single fusion and extrusion weldings. Equipments of vacuum test consist of :
1. A vacuum box consisting a well-built cabin, a see-through observation window, a soft rubber gasket mounted to the bottom, and vacuum engine.
2. A plastic bucket and a wide brush.
3. A bubbly solution.  

The test executive will fulfill the items below :
1. Extra parts of the overlap will be cut.
2. Vacuum box observation window and surfaces of gasket will be cleaned, possible leakage points will be checked.
3. Approximately 30 cm x 120 cm (dimensions of the box) of the surface of geomembrane is dampened with the bubbly solution.
4. The box is put on the wet part and pressed down.
5. Vacuum engine is turned on and vacuum box is enabled to suck the geomembrane
6. Leakages are checked.
7. It is checked from the observation window for approximately 15 seconds that there is no bubbles on the geomembrane.
8. If there is no bubbles for 15 seconds vacuum engine is turned off and membrane is released. Overlaping 15 cm. to the tested area, the same procedure is repeated for the next part.
9. Every part that bubbles are seen should be marked, repaired and re-tested

Spark Test
1. A copper wire is placed all along the extrusion welding line.
2. Extrusion welding is applied on the copper wire.
3. Then it is checked with the spark machine if there's any leakage.
4. If there is any leakage it is repaired with extrusion .

4.4.2 Air pressure test (only for double fusion weldings)
Below method is used for the tests of double fusion weldings. Necessary equipments for tests of double fusion weldings are :
1. An air pump with a pressure room which is able to create and hold a pressure of 25-30 psi (1.75-2.10 at) , which is mounted on a pad to protect geomembrane .
2. A manometer mounted sharp tipped needle or another approved pressure feeding tool.  

Executive will fulfill the list below for the test :
1. One end of the welding to be tested is blocked.
2. The needle or approved pressure feeding tool is inserted from the blocked end of the channell made by double fusion welding.  
3. Pressured air is pumped to see if the air channell is totally clean.
4. The other side of the channell is also blocked.
5. An air pressure of 25-30 psi (1.75-2.10 at) is blown inside with the air pump and the valve is turned off. After waiting 2 minutes to balance, the pressure is kept inside for approximately 5 minutes.
6. If the pressure leakage is more than 4 psi (0.28 at) or the pressure is not stable, the leakage would be found, repaired and retested.

4.5.1 Repairment procedure
1. Defected and wrong weldings should be repeated as shown on this specification.
2. Small holes can be repaired by extrusion welding but if the hole is big, it should be patched.
3. Tears must be patched. If the patch is on slope or on a tense part and has a sharp edge, this edge is given a round shape before welding not to allow it to get longer
4. Wide holes, defected parts caused by raw material not homogenically spread and parts effected by any external attack must be patched.
5. The HDPE geomembrane surface to be patched must be cleaned and grinded earliest 10 min. before the repairment. Grinding musn't be more than 10% of the thickness. Welding must be started where the grinding starts and must overlap on the previous welding minimum 5 cm. If there will be another extrusion on top of an old extrusion, the surface of the old extrusion must be grinded.

Patches must be round or elliptical shaped and must overlap the edge of defected part at least 15 cm. All the patches must be with the same thickness and have the same properties as the geomembrane being used. Edges of all patches must be bent by grinding with angled grinder before they are placed on the geomembrane. The patches can only be applied by using the approved methods.

4.5.2. Repair checks Recording results :
Documents showing the results of all the tests done by the executive are recorded daily. These documents include the evidences showing that all the weldings are tested, failed parts are repaired and re-tested successfully.

5. Filling the anchorage ditch
It must be done very carefuly not to damage geomembrane, geotextile, or geonet. If a damage occurs, it must be repaired before the filling procedure finishes.

6. Approval of a geomembrane application Executive holds the full responsibility of geomembrane application until the owner accepts. Approval of geomembrane is possible with the conditions listed below :
1. Procedure must be totally finished .
2. Controls weather all the site weldings and repairs have been done with the necessary tests, will be finished
3. All the documents and AS BUILT drawings prepared and handed over to the authorized level by the executive.