1 / 25

Madagascar Water Supply Project: TAC Review Summary May 14, 2013

Madagascar Water Supply Project: TAC Review Summary May 14, 2013. Ambalona, Madagascar. Population: ~800 Households: ~160. Project Objective : Domestic Water Supply. ~125 m. Project History. May, 2008: Initial Visit December, 2009: Test Well Installation

benito
Download Presentation

Madagascar Water Supply Project: TAC Review Summary May 14, 2013

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Madagascar Water Supply Project: TAC Review SummaryMay 14, 2013

  2. Ambalona, Madagascar

  3. Population: ~800 Households: ~160

  4. Project Objective: Domestic Water Supply ~125 m

  5. Project History • May, 2008: Initial Visit • December, 2009: Test Well Installation • March, 2012: Follow-Up Assessment • Status of test wells • Feasibility of a gravity flow system

  6. Test Wells May, 2008: Initial Visit December, 2009: Well Installation March, 2012: Follow-Up Assessment

  7. Test Well Status School Well • Working since installation • Serves entire village Village Well Several breaks in service Low yield/sediment

  8. Gravity Flow Springs nearby Technically feasible High capital cost Sustainable?

  9. Project Process October, 2012: Alternatives Analysis Report December, 2012: Preliminary Design Report January, 2013: Pre-Implementation Report February, 2013: TAC Review

  10. Alternatives Analysis Gravity Flow Wells & Hand Pumps BioSand Filters Wells, Solar Powered Pumps & Elevated Water Tanks

  11. Preliminary Design Demand Analysis: For this population, five communal water supply points are required to meet basic water needs – 20 l/capita-day Four new wells India MK III pumps ≥100-mm casing (allowing for later installation of solar pumps, if desired)

  12. Preliminary Design • Modeled multiple well scenarios with AQTESOLV Hydrogeology: Based on test well logs and slug tests, assumed unconfined conditions, Kh = 2-5×10-5 cm/s Depth-to-water varies seasonally: ~3-7 mbgs Porosity, anisotropy, etc. estimated

  13. Preliminary Design TD: 39.5 mbgs Screened Interval: 8 – 38 mbgs Sump: 38 – 39.5 mbgs Casing: 100-mm SCH 80 PVC Borehole: 40 mbgs Cement grout surface seal: 0 – 6 mbgs Washed sand filter pack: 6 – 40 mbgs

  14. Preliminary Design India Mk II/III pumps Sloping concrete apron Protective casing Fenced enclosure

  15. Preliminary Design • Well siting criteria: • Locations decided with community • Provide reasonable access • At least 30 m from human waste disposal • At least 15 m from food/wastewater disposal • At least 30 m from animal housing • Outside areas susceptible to flooding • Solicited bids from three drilling contractors • Phased implementation: build two now, monitor, build remainder next year

  16. TAC ReviewContext Follows initial technical approval of Pre-Implementation Report by Project Manager Requires short (20 minute) webinar presentation to one of the regional Technical Advisory Committees (not necessarily home region TAC) TAC reviews Pre-Implemetation Report, HASP and slides prior to presentation Q&A session follows presentation More than one project may be on the agenda

  17. TAC Review:Presentation Structure 24 Slides Country Background: 3 Slides (12.5%) Community Background: 3 Slides (12.5%) Project Overview, Including Objectives, History, stakeholders: 6 Slides (25%) Alternatives Analysis: 1 Slide (4%) Preliminary Design: 11 Slides (46%)

  18. TAC Review:Q&A 12 Questions Country Background: 0 Questions(0%) Community Background: 0 Questions(0%) Project Overview, Including Objectives, History, stakeholders: 0 Questions(0%) Alternatives Analysis: 0 Questions(0%) Preliminary Design: 12 Questions(100%)

  19. TAC ReviewQuestions/Comments Why does the well have a sump? What is the minimum/maximum grain size of the filter pack? Has the depth of the village test well been measured to determine is it has been filling up with sediment? Will centralizers be used to keep the casing in the center of the borehole?

  20. TAC ReviewQuestions/Comments The preliminary design is for 39 metre wells, compared to 18 metres for the test wells. If the driller is unable to go to 39 mbgs, it may be possible to get sufficient yield from a shallower well. What water quality testing has been done? The pH of well water is in the range 4.7 – 5.4. How will this be addressed? The Denver wiki shows a high coliform count for the village well.

  21. TAC ReviewQuestions/Comments The design is based on demand of 20 l/capita-day. This is too low. Some wells are telescoped (i.e., borehole diameter is wider near the surface and narrows with depth). Was this considered? The setbacks specify 15 metres from the wellhead to food/wastewater disposal areas. This should be 30 metres.

  22. TAC ReviewResponse If TAC questions and comments are not resolved during the Q&A following the presentation, the project may be put on hold until these issues are they are. Don’t panic! This is perfectly normal. All questions and comments to be resolved are provided in writing. Responses are submitted in the a Form 809 report – Response to TAC Comments Can be an iterative process

  23. TAC ReviewResponse • All questions and comments must be addressed, but acceptable responses may vary from compliance to dispute, as long as they are technically sound. • Examples: • A more comprehensive water quality monitoring program will be implemented; 30 metre setbacks will be introduced • The 20 l/capita-day design basis was retained; telescoped well was not necessary or feasible

  24. TAC ReviewConclusion The Madagascar project submitted responses two weeks after being put on hold. The TAC gave techinical approval ten days later The project will be traveling to Madagascar this June to install two new wells in Ambalona

  25. Final Note Wiki as a means to preserve and share TAC experiences?

More Related