International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 3, March 2017) 30 Construction of Pond in a Sandy Strata with Mixture of Sand and Bentonite as Liner Dr. Manish Gupta 1 , Dr. R. Chitra 2 , C. B. Sarma 3 1 Divisional Head (GS&S), 2 Group Head (Soil), 3 Assistant Research Officer, Central Soil and Materials Research Station, New Delhi, India Abstract— Well graded compacted sands are stable materials. But these coarse grained soils are pervious when devoid of fines. When sands become finer and uniform, its characteristics are similar to that of silts possessing decreased permeability and reduced stability in the presence of water. Mixing sand with the optimum amount of bentonite, gives a sand-bentonite mixture with a low drainage characteristics. Bentonites mainly the sodium bentonite has been proven to be the most effective liners in the geotechnical engineering practice. The sodium bentonite swells to many fold when it gets contact with water and forms a good sealant to be installed in the ponds. Since it does not contain any chemical, additives, any toxic material, the sodium bentonite is named as environmentally friendly material. In order to arrive at the optimum amount of bentonite to be mixed with sand for the desired hydraulic conductivity, detailed investigations are carried out. Further, the thickness of the sand-bentonite mixture layer is designed with allowable seepage loss. The soil investigations for an artificial pond to be constructed in the western part of the state Uttar Pradesh for a botanical garden in a sandy stratum was undertaken by CSMRS. The paper presents the geotechnical investigations carried out on the samples of bentonite, sand, sand – bentonite mixture and the design of the bentonite lining layer. Keywords— Pond Liner, Sand, Bentonite, Permeability, Seepage Loss, Soil Investigations. I. INTRODUCTION Water containment systems such as ponds, reservoirs, canals etc. and the waste containment systems are required to be lined in order to prevent any seepage losses or leakages of the leachates leading to the ground water contamination. Generally clay and synthetic liners are used for preventing the leakages. Though the compacted clay liners which are impervious material usually possess a hydraulic conductivity less than 1×10 -7 cm/sec, it is difficult to fulfill its function with sand which is a pervious material. Usually the hydraulic conductivity of the sand ranges from 1.0 to 1×10 -5 cm/sec depending on the percentage of fines present. The hydraulic conductivity of the sands can be reduced remarkably by mixing the sand with a highly impervious material such as cement, bentonite and any workable chemicals. Bentonite comprises of montmorillonite group of clay minerals possess high cation exchange capacity, large specific area, high swelling potential and totally impervious. Specifically, the sodium bentonite has been proven to be a liner material. It does not contain any harmful chemicals, additives, any toxic material which has named the sodium bentonite is named as environmentally friendly material. Extensive and meticulous investigations are required to arrive at the optimum amount of bentonite to be mixed with sand for the desired hydraulic conductivity. Moreover, for the given amount of seepage loss allowed, the thickness of the sand-bentonite soil mixture is determined. The soil investigation for the pond to be constructed for a botanical garden was undertaken by CSMRS. The present paper presents the studies carried out on the different components of the pond. II. BENTONITE Bentonite, a form of clay, is absorbent aluminium phyllosilicate clay consisting mostly of montmorillonite. Different types of bentonite namely, potassium bentonite, calcium bentonite, sodium bentonite and aluminium bentonite are available. However, only two types of bentonites namely the Sodium Bentonite and the Calcium Bentonite are extensively used for the industrial purposes (drilling muds, thickeners for slurry trenches, landfill and pond liners, floculents, foundry sand binders, and animal feed binders, binders and carriers for pesticides and drugs). The Sodium Bentonite has a natural swelling ability and maintains its swelling ability throughout its use. The Calcium bentonite is a non-swelling bentonite and it does not swell without any additives or chemicals but the enhanced swelling characteristics lost for very short period only. The swelling ability of the sodium bentonite enables it to bond with the soil to create an impermeable layer in the soil. Sodium bentonite is a natural sealant and is used for sealing stock and recreational ponds, dairy and sewage lagoons, and city landfills. It is also effective as a hole plug as well as for controlling dust on highways. Sodium bentonite is one of the most effective low cost methods of treating porous soils. It is environmentally safe, because it contains no chemicals, no additives, nothing toxic.