QUALITY CONTROL PRESENTATION ON IWMP 1

 Soil and moisture conservation  Importance and focus to water/Moisture conservation 2

 Check dams  Check walls  Mini Percolation Tanks  Percolation Tanks and drainage line treatment works. QC’s intervention:  First time QC was given works of watersheds (Mainly taken up under MGNREGS) about 6 to 8 works in 64 assigned works since last December  Exclusively watershed works in (12) districts under implementation since April

 a)Men at cutting edge level:  1. Staff manned at watershed/micro watershed are relatively fresh to work  2. Their confidence levels need boosting, though they are knowledged about concepts of watersheds.  3. They are enthusiastic and eager to learn and improve their confidence levels.  4. They don’t have minimum equipment to help in selection of suitable sites. 4

(b) works:  1. More that 30% to 40% of works grounded are having poor site selections.  2. Poorer implementation of standards in execution.  3. Oversized sections adopted causing wasteful expenditures. Estimates in Software  1. The different tasks provided in estimates need relook for revisions/modifications/additions.  2. More meaningful “Input data” is to be sought in software of estimates before generation of estimates. 5

 1. Regular orientation courses are to be conducted to lower level field executives who are relatively in experienced and in-exposed.  2. Field visits to best & bad executed examples are to be madefor better understanding.  3. Minimum field tests to be conducted to help selection of sites are to be told and demonstrated.  4. Needed field kits and tools are to be provided to them to help correct selections of sites.  5. Collection of relevant “Field data” and feed of such “Field data” is to be made prerequisite “input” for opening of “Software” for estimate preparation.  6. Needed modification of tasks (or) adding additional tasks.  (a) Adding flexibility to existing task specifications is to be made in software. 6

 A.Percolation Tanks/Mini Percolation Tanks.  1. Locations identification is not done properly  a) Impermeable soils are selected where percolation is either nil or negligible.  2. Saucer like locations/sloping terrains are not selected.  3. Soil cover availability is not checked.  4. Borrow pits are put abutting bunds which will result in destabilizing of bund if not piping action. 7

 5. Consolidation of bund is poor or with practically nil compactions.  6. Slopes are not being maintained which will cause slipping of slopes.  7. No concept about purpose & location of toe wall.  8. Revetment work is done without packing and preparing the slope of bunds.  9. No visualization, what so ever about possible storage depths in PTs & MPTs.  a) Average storage depth in many cases is one meter (or) below which will result in more losses in evaporation than percolation (in MPTs).  b) In PTs the depth of storage never exceeded 1.5m (or) 1.6m that too in borrow pit portions.  10. Surplus course is neither designed nor located properly. 8

Remedies suggested:  Make through study of topo sheet of the area before site selection.  Identify from topo sheets, possible locations & proceed & inspect site & locate site at field with above data.  Make it a habit and mandatory to identify ordinates of site(longitude and latitude)  Verify suitability of soils at location for permeability  Verify soil cover existing (min 1m) & whether there is any change in classification of soils.  Verify suitability of soils for bund formation either for homo- genious section (or) composite section.  If soils is suitable for composite section only identify source for core & key 9

 From topo sheet identify catchment area to site selected. Workout possible runoff and fix up storage capacity depending upon number of sources near by to be benefitted.  Provide the surplus course/ bye-wash at high contour nearer to natural course, if not possible provide suitable lead drain to natural course from surplus weir/bye wash.  i) 1.Provide top width of min 2.5 m to ensure total power roller consolidation (for PTs)  2. For MPTs provide top width of 1.5m & ensure power roller consolidation upto FTL.  j) Ensure to have proper consolidation along with watering.  If power roller is not available. 10

Other options of cattle treading hand roller rolling (2T) with reduced earthen layers must be adopted.  K).Depending upon intensity & magnitude of runoff, the max depth of flow over surplus weir is to be worked out. Possible area of inundation at max water level is to be identified & bunds are to be extended accordingly. 11

 After finalizing length & height of bund, arrive at sections of bund at regular intervals  Mark locations on ground: Fixup centre line of bund.  Mark bottom widths along the alignment and connect toe lines & heel lines of sections to get plan of bund at bottom  Strip top loose soils of measured area upto 15cm and upto 23 cm (or) 30cm if vegetation is deeprooted and keep the soils aside on out side of bund (along toe line) for reuse.  Based on need cut key trench of min 1.5m width(to facilitate rolling) 12

 Refill key trench with excavated soils (if suitable) or borrowed soils ensuring needed compaction.  Roll the stripped surface of bund before actual bund formation  Ensure the layers of soils put are not more than 30cm in case of power roller & 15cm in case of hand roller to ensure better compaction 13

 Check the level of compaction with proctor’s needle before spreading next layer.  Simultaneous verification of availability of moisture in soils at time of compaction is to be done.  After completion of bund formation, the slopes are to be trimmed off loose and un-compacted soils.  Water side slope is to be properly rammed before taking up revetment work  Toe wall of 0.45m min is to be provided to a min depth of 0.45m and if needed can be extended upto 0.6m to ensure stable firm resting. 14

 Necessary bond or key stones are to be provided and ensured to have proper disbursement of load from top.  The revetment must be started from bottom from top of toe wall & is to be built up the slope. The revetment must rest stabily & firmly on top of toe wall, to prevent, slipping, sinking etc.  Packing of revetment with proper keys is to be ensured for preventing slipping (or) sinking of revetment due to wave action.  Where ever the soils of bund are expansive, the revetment must be backed by gravel packing. 15

Correct and favorableIn Correct (Unfavorable) Weir 16

H Semi –Peramiable soils/Permiable soil (Non Porous) H=Min 1 m Soil Strata GL Rock/fissured/fractured 17

H Barrow Pits Min >5H Correct Location Barrow Pits Incorrect Barrow Pits O/S W/S 18

H B O/F W/F L 1 = 1.5 H or 2 H L 2 = 1.5 H Correct H B O/F W/F L 1 < 1.5 H L 2 < 1.5 H In Correct 19

Stone Packing CorrectIn Correct Stone Packing 20

Bund Section C/S of Bund 21

In Plan Strip top soil 0.15 to 0.3m 22

Packing wedge stone pieces Correct Incorrect 23

h FB H =storage depth FB =Free board H=free board protected (wave action) Avg H=H av Max H=H max H max :Max Storage depth 4to 52.7 H av : Avg Storage depth 2.5 m1.5m 0.75 to 0.9 m0.6 m 0.2m 0.15m For PTs MPTS 24

B =Min 0.45 m H =Min 0.45 m to 0.6 m (or) 0.75 m Toe Wall H Incorrect Placement Toe Wall W/F Correct Placement In Correct Placement 25

Water Body Deep bed Water Body Natural courses Lead channel a b 26