2.1 Study area
The experimental plot was established on the solid waste dump of the
Nalwa Steel and Power Limited (NSPL) located in the Raigarh district of
Chhattisgarh, India (Figure 1). NSPL is an operating integrated steel
plant that manufactures sponge iron by the direct reduction process. The
aerial extent of the waste dump lies between 83º22’35”E to 83º23’27”E
and 22º00’51”N to 22º02’10”N covering an area of approximately 7
hectares. The dump height ranged between 40-50 m with a slope of more
than 60–70º inclination. The area experience subtropical climate with
temperature ranged between 8–49oC and the mean annual
precipitation was 750 mm. The waste materials were dumped externally at
the outskirts of the steel plant surrounded by Shorea robustadominated forest.
The main stages involved in sustainable closure and subsequent
reclamation of the waste dump were as follows (Figure 2): (a) leveling
of the surface, compaction and maintaining slope of 1:3 for proper
surface runoff, (b) re-grading of slopes and blanketed with coirmats
followed by topsoil and seeded with grass-legumes seeds, (c) safety
measures like stone pitching at the toe of the dump and construction of
garland drain, (d) re-grading the surface before applying forest topsoil
up to 0.6-1 m depth, (e) for stabilization of the slope and sidewalls
coir mats of dimension (1m × 30m) were used, (f) for the development of
green cover in the initial stage, seed mixture of grass (P.
pedicellatum ) and legume (S. hamata ) in a 1:1 ratio was sown.
the view of stabilized dumps after 5 years, with the development of
mulch covers in lean season (summer), is shown in Figure 3. In the berm
of dumps, tillers of lemongrass (Cymbopogon citratus ) were
planted. Tree species like Azadirachta indica , Leucaena
leucocephala , Acacia nilotica, Pongamia pinnata were also
planted on the edges to increase dump stability.