griha criterion 3

Criterion 3Soil conservation (till post-construction)

Objective

• Conserve top soil till after completion of construction activity.

Top soil preservation in Doon School, Dehradun

Commitment

• Ensure adequate fertility of the soil to support vegetative growth.• Ensure adequate topsoil laying for

vegetative growth.• Ensure stabilization of soil in the area

where the topsoil is vulnerable to erosion.

Top soil preservation

Compliance

• The following documents to be submitted.• Site contour plan (one CAD drawing) showing drainage pattern and

demarcating.areas where top soil laying is done, and area where vegetation cover is provided for top soil protection.

• Narrative explaining the methods of soil stabilization used; wherever required, accompanied by photographs with brief description.• Certificate by the landscape architect on topsoil laying, soil stabilization, and

adequate primary soil nutrient and pH [(supported by test results performed at Indian Council of Agricultural Research (ICAR)–accredited laboratory].

Appraisal (maximum points 2)

• Proper top soil laying for vegetative growth• Proper stabilization of soil, Non Applicability condition: For sites in

which top soil could not be stored for reasons as cited in Criterion 2.


Preserve the excavated soil (till post construction)• Soil Composition – Top soil (15-20 cm) layer is nutrient rich. The purpose of soil conservation is to use the

available fertile soil on the site for the landscape use in the proposed building, and also to avoid the import and transportation. If the soil is not having enough nutrients for fertility then, it has to be enriched. Following characteristics should be checked to assure fertility in the soil.

Presence of organic carbon helps in soil aggregation and improves water-holding capacity, which helps in slowing down the flow of water through soil. The optimum level of organic carbon in the soil ranges from 0.5%–1.0%.

Maintain a pH of 6.0–7.5; add lime where pH<6.0 to adjust to 6.5 or higher (up to 7.5). Any soil having soluble salt content >500 ppm (parts per million) shall not be used for the purpose of

landscaping. Ensure presence of basic inorganic nutrients (nitrogen, phosphorus, and potassium) in adequate amount for

healthy growth of vegetation. If required, ensure proper and timely application of fertilizers to enhance soil fertility.

Deficiency of organic and inorganic material can be improved by application of fertilizers, but care should be taken so as to avoid over fertilization.

The soil should be tested at an ICAR (Indian Council of Agricultural Research)- accredited laboratory for primary plant nutrient and pH.

Soil preservation-till post construction • Identification of the areas where the top soil (collected from the

entire site) can be stacked, stored and mulched. The site has a rich cover of fertile soil. In a general practice is soil is either wasted or thrown away at the time of construction. And at the time of landscaping nutrient rich soil is imported in the site. As a good practice, it is recommended to take top 20 cm layer of soil out and store it at some place at site. This soil shall be stabilized with pebbles, grass or some kind of vegetation. Same soil shall be used for landscaping of this site.

• Water and dissolved chemicals move more quickly through coarse textured, sandy or gravelly soil, fine textured silt, and clay soils. Soils high in organic matter slow down the flow of water and vegetation cover is an effective means to stabilize disturbed soil. In areas where construction activity has disturbed the land, temporary/permanent seeding should be used till the final soil cover is established.


• Permanent plantation should be done in areas where high velocity of water flow poses a problem of erosion—like buffer, vegetated swales, and steep slopes (grade>1:3). The foliage effectively dissipates the energy of heavy rain and roots hold the soil, thus preventing soil erosion. The vegetation selected for the purpose should be an indigenous species.• The use of mulches on slopes can help prevent run-off

and erosion problems. Few of the organic mulch materials include shredded bark, wood chips (waste from furniture industry), straw and cottonseed hull, composted leaves or shredded cedar. Inorganic mulches such as pea gravel, crushed granite, and pebbles should be used in unplanted areas. Stone mulches should not be used in areas immediately adjacent to buildings as they can heat up and cause glare.


Silt fencing

• It is recommended to construct Silt Fencing. It is required to protect the undisturbed areas. Following is one of the ways of doing it. Several geotextile materials are coming in the market. These materials are made of tough fabrics that have quality to retain the soil. These materials are usually in the landscaping and farming. As a common practice, these are placed at the bottom of lawn areas or planters to retain soil and block weeds. An example of geotextile is shown in figure

Geotextile

• Construct sediment fence as close as possible to parallel to the contours of the site. • Drive 1.5 m long star pickets into ground, 2.5 m apart (max). • Dig a 150 mm deep trench along the upslope line of the fence for the bottom of the

fabric to be entrenched. • Fix self supporting geotextile to upslope side of posts with wire ties or as

recommended by geotextile manufacturer. • Join sections of fabric at a support post with a 150 mm overlap • Backfill the trench over the base of the fabric and compact it thoroughly over the

geotextile.

DISTURBED AREA UNDISTURBED AREA

GEOTEXTILE SILT FENCING