Page 34 - DPR Rishikesh Legacy_Neat

11. Post-closure care should be 15 years with monitoring of leachate (to be treated or
sent to a sewage treatment plant [STP]), gas generation, and groundwater quality
(in monitoring wells).

These components are described in detail in the following subsections.

4.1.1 COMPONENTS AND INTERVENTIONS OF SCIENTIFIC CLOSURE

The final cover layer is to be applied to the entire dumpsite surface after confining
the dumpsite into smaller footprint area and grading into the designed slope. The
final cover usually consists of multiple layers designed to enhance surface
drainage, intercept percolating water and support surface vegetation. The final
cover shall have a barrier soil layer comprising of 60cm clay or blended soil with
-7
permeability coefficient less than 1 x 10 cm/sec. The barrier soil layer is capped
by a drainage layer of 15cm. The drainage layer shall then be capped by a
vegetative layer of 45cm to support natural plant growth and to minimize erosion.

A grain size analysis for every 400 cu.m of material used is recommended for
quality control purposes. The layer shall be compacted to above 95% density to
provide a firm sub base for the low – permeability layer above. The density shall be
tested at 30 m grid points.

Laying of the topsoil layer shall be done as soon as the protective layer
construction is finished. Heavy construction equipment shall not be allowed on the
finished surface. The nutrient and liming requirements for the topsoil shall be
assessed from a competent agricultural laboratory. In the absence of a regulatory
recommendation/ requirement regarding seed mix, a horticulturist or soil scientist
shall be consulted. A combination of grass and bush type vegetation capable of
surviving without irrigation water shall be planted. At least five samples of topsoil
per hectare shall be tested for nutrient and liming requirements. Nutrient and seed
mix application rates shall be supervised on site for quality control purpose. Utmost
care shall be exercised in installation of the gas vents in the final cover where ever
to be provided.

The final cover shall have a gradient of 3 to 5% to assist surface runoff. Lined
ditches or channels are constructed on the final cover to intercept and carry
surface water off the cover to the storm water basin.

4.1.2 LANDFILL CLOSURE
For the closure of open dumpsite, the following interconnectivities are established:

- The surface water drainage system for the cover of each phase is to be
connected (if so designed)
- The gas collection system (if provided) of each phase is to be connected.
- An access road is provided on the landfill cover to enable easy approach for
routine inspection & maintenance of landfill cover.

4.1.3 POST CLOSURE STABILIZATION, OPERATION AND CARE

4.1.4 LONG –TERM VEGETATIVE STABILIZATION
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