METHODOLOGY FOR FILLING OF OPEN WELLS

 FILLING OF OPEN WELLS

SCOPE:-

This work consists of

Ø  Removal and disposal of all unsuitable and obstructing material.

Ø  Demolition of well lining, placing of selected material in layers and compaction of the same.

This methodology is applicable for open wells with size < 6m dia over which road embankment would be built.

 DEFINITIONS :

abbreviations:

                                    MoRTH         :           Ministry of Road Transport & Highways

                                    M.D.D.           :           Maximum Dry Density.

                                    O.M.C.           :           Optimum Moisture Content.

                                    BOQ               :           Bill of quantities

     

CROSS REFERENCES :

1)      MoRTH – Specifications for Road and Bridge Works ( Fourth Revision )

2)      Technical Specifications

CLASSIFICATION OF WELLS:-

The open wells will be classified as

(a)   Lined

(b)   Unlined

The casing / Lining of wells may be of masonry, burnt clay, concrete rings or any other type.

MATERIALS:-

Ø  The fill material shall be non-compressible  type and free from any hazardous material/sewage.

Ø  The fill material is as given in the table.

Ø  The size of coarse material in soil not exceeds 25mm and incase of sand and gravel mixture, the maximum size not more than 75mm.

Ø  The selected material (Soil and sand-gravel mixtures) shall have MDD as per IS:2720,part 8)not less than 16.0kN/m³ .The Sand-Gravel mix shall be as per sub clause 2504 .

SlNo	Description	Material Type
1	Well with standing Water	Ø  Mixture of Sand And Gravel(80:20) up to 1.5m height below natural ground level. Ø  The Selected granular soil with plasticity Index (PI) <6 for the remaining depth of well. Ø  To achieve desired compaction the top 1.5m shall be executed by lowering the standing water level by more than 1.5m below natural ground level.
2	Dry Well with Depth	Ø  Mixture of sand and gravel up to 1.5m height below natural ground level. Ø  The selected granular soil with plasticity Index (PI) < 6for the remaining depth of well.
3	Well size less than 1m diameter	Ø  Mixture of natural sand and gravel

 CONSTRUCTION OPERATION:-

Ø  All the debris such as pump, metal wires, rods, etc., and floating material will be removed.

Ø  In case of lined wells the lining shall be dismantled up to the level of natural ground level or one meter in height   whichever is higher.

Ø  Upper 1m of well casing /lining shall be removed when the fill material within 1m of the existing ground surface.

Ø  Stagnated water shall be treated by adding Chlorine bleach @ 5lit /2500 liters of standing water.

Ø  Inspection of the well after the above steps are completed shall be done before filling operation.

Ø  The placing and compaction of operation will be done as per Clause A-10,4d(I to v)

Ø  The layer so compacted is inspected to carryout next layer for placing and compaction.

Ø  The details of construction  operation is explained in the Flow Chart  attached.