14.3 HAZARDOUS WASTE MANAGEMENT

14.3.1 Inventorisation of Hazardous Waste

The Central Pollution Control Board had taken up studies on inventorisation of hazardous waste generation in various States, with a view to identify hazardous waste generating units, quantification of hazardous waste generated and present practices adopted for hazardous waste management by various industrial sectors. During the year, studies in the States of West Bengal, Tamilnadu and Union Territory of Chandigarh, Pondichery, Daman, Diu & Dadra Nagar Haveli, have been completed.

14.3.2 Criteria for Hazardous Waste Disposal to Landfill and Management of Leachate

The hazardous wastes generated by the industries are required to be disposed in secure landfill. The landfill sites generate leachate. If leachate is not collected and treated properly, it may contaminate groundwater resources. In view of the hazard characteristics of leachate. CPCB has taken up a project on "Development of Standards for Leachate from Hazardous Waste Disposal Site". The project has been completed and the draft report has been prepared containing identification of hazardous waste suitable for land disposal, guidelines for leachate collection & removal system, criteria for disposal of hazardous waste into secure landfill and suggested treatment options for treatment of leachate generated from hazardous waste landfill site and environmental standards for leachate. The criteria for disposal of hazardous wastes in landfill and leachate collection, removal and detection systems, as suggested in the report, are as follows.

Criteria for Disposal of Hazardous Wastes in Secure Landfill

Depending upon the characteristics of wastes and the reactivity of the wastes with each other as well as with the liner system, the wastes which could be allowed be identified. The wastes coming to the facility for the disposal must be de-watered up to the level of 60 - 70% solids, from the stability point of view, the following listed wastes should not be allowed to dispose off directly into the landfill facility:

• Waste, which is a fluid, slurry or paste.
• Waste, which is delivered under pressure or under vacuum.
• Waste, which has an obnoxious odour.
• Waste, which reacts with moisture to produce considerable amount of heat or gases.
• Waste, which is highly inflammable (flash point < 550C).
• Waste, which contains shock sensitive substances.
• Waste, which contains very strong oxidizing agents.
• Waste, which contains volatile substances of significant toxicity.
• Waste, which falls below a pH value of 4 and exceeds the value of 13, if evaluated in distilled water in the ratio of 1 : 10.
• Waste, which possesses a calorific value of more than 3200 Kcal/kg. These wastes have to go for authorised energy recovery or for incineration.

In addition to above, the criteria for disposal of hazardous waste into secure landfill facility has been recommended in the guidelines, which is presented in Table 14.1.

Leachate collection, removal and detection system

The components of leachate collection, removal and detection system are:

• leachate collection and removal system (LCRS)
• leachate detection and removal system (LDRS)

The leachate collection and removal system shall comprise of the following components:

• Drainage layer
• Filtration/protected layer
• Drainage pipe and channel
• Collection sump and leachate collection pump

General requirements for a leachate collection and removal system are that it should

• be able to drain down leachate within the landfill such that the leachate head acting on the base of the landfill is less than one foot.
• be strong enough to withstand physical damage due to loading imposed by the waste and any compaction equipment working over the system
• be able to accommodate the predicted settlement at the base of the land fill under the applied loads and foundation condition
• be resistant to chemical attack of the waste in land fill
• be able to function without clogging during and after the operational life of the landfill
• be capable to inspection and maintenance until such time as the system is no longer required to function.
• incorporate a suitable level of redundancy in the design taking into account failure of parts of the system and provide alternate drainage route to collection point

Leachate removal from the landfill site could be carried out by two methods depending upon the site design i.e.

• By gravity - this system could be used where the landfill base is at ground level or at shallow depth; and
• By pumping - this system could be used where landfill base is below ground level

Table 14.1: Recommended Criteria for Hazardous Waste before Disposal into SLF