Design Project - Systems Modelling and Design

CVEN30010​ ​SYSTEMS​ ​MODELLING​ ​AND​ ​DESIGN DESIGN​ ​PROJECT

Kira​ ​Martin​ ​758835 October,​ ​2017

1

Table​ ​of​ ​Contents

Executive​ ​Summary

3

Introduction

3

Ground​ ​model

4

Water​ ​Storage​ ​and​ ​Catchment

4

Town​ ​Water​ ​Supply​ ​System

6

Water​ ​Tower

8

Water​ ​Supply​ ​System​ ​for​ ​Farms

9

Stability​ ​of​ ​Existing​ ​Slopes

11

Embankment​ ​Dam

14

Environmental​ ​and​ ​Social​ ​Impact​ ​Assessment

17

Conclusions

19

References

20

Appendices

21

2

Executive​ ​Summary

In​ ​this​ ​design​ ​report,​ ​a​ ​conceptual​ ​design​ ​of​ ​a​ ​water​ ​storage​ ​reservoir​ ​(The​ ​Reynoso​ ​Reservoir) and​ ​connecting​ ​water​ ​supply​ ​systems​ ​is​ ​proposed.​ ​The​ ​design​ ​process​ ​took​ ​a​ ​linear​ ​approach,​ ​as a​ ​set​ ​of​ ​steps​ ​that​ ​continually​ ​increased​ ​in​ ​detail​ ​and​ ​analysis​ ​were​ ​followed.

Firstly,​ ​a​ ​critical​ ​geological​ ​cross-section​ ​of​ ​the​ ​ground​ ​model​ ​was​ ​designed​ ​using​ ​Adobe Illustrator.​ ​This​ ​cross-section​ ​includes​ ​the​ ​ground​ ​surface​ ​level,​ ​ground​ ​layers​ ​with​ ​depths​ ​and location​ ​of​ ​the​ ​groundwater​ ​table.​ ​Next,​ ​a​ ​water​ ​storage​ ​and​ ​catchment​ ​model​ ​was​ ​generated through​ ​an​ ​Excel​ ​Spreadsheet,​ ​which​ ​provided​ ​the​ ​engineering​ ​team​ ​with​ ​the​ ​appropriate catchment​ ​area​ ​for​ ​the​ ​predicted​ ​precipitation​ ​levels​ ​in​ ​the​ ​area​ ​that​ ​will​ ​create​ ​a​ ​reliable​ ​supply water​ ​to​ ​Martinville​ ​and​ ​the​ ​farms.

The​ ​water​ ​supply​ ​systems​ ​for​ ​Martinville​ ​and​ ​farms​ ​were​ ​then​ ​analysed,​ ​developed​ ​and proposed.​ ​Firstly,​ ​a​ ​pipeline​ ​route​ ​was​ ​designed​ ​from​ ​The​ ​Reynoso​ ​Reservoir​ ​to​ ​Martinville,​ ​and through​ ​analysis​ ​of​ ​different​ ​diameter​ ​options​ ​for​ ​piping,​ ​an​ ​optimal​ ​diameter​ ​was​ ​chosen.​ ​A schematic​ ​diagram​ ​of​ ​pump​ ​positioning,​ ​as​ ​well​ ​as​ ​installation​ ​and​ ​operating​ ​costs,​ ​is​ ​also included​ ​in​ ​the​ ​report.​ ​Additionally,​ ​a​ ​water​ ​tower​ ​design​ ​for​ ​Martinville​ ​was​ ​proposed​ ​in​ ​the​ ​case of​ ​emergency​ ​situations.​ ​The​ ​geometry​ ​of​ ​the​ ​water​ ​tank​ ​and​ ​tower​ ​are​ ​presented.​ ​Lastly​ ​for​ ​the water​ ​supply​ ​systems,​ ​the​ ​system​ ​to​ ​supply​ ​water​ ​to​ ​the​ ​farms​ ​is​ ​considered.​ ​This​ ​is​ ​proposed​ ​in the​ ​form​ ​of​ ​two​ ​concrete​ ​open​ ​flow​ ​channels,​ ​and​ ​their​ ​optimal​ ​cross-sections​ ​are​ ​presented​ ​in the​ ​report.

Referring​ ​back​ ​to​ ​the​ ​geological​ ​cross-section,​ ​the​ ​stability​ ​of​ ​the​ ​existing​ ​slopes​ ​in​ ​the​ ​valley where​ ​The​ ​Reynoso​ ​Reservoir​ ​is​ ​to​ ​be​ ​constructed​ ​is​ ​analysed.​ ​Using​ ​the​ ​software​ ​of​ ​SLOPE/W, stability​ ​of​ ​the​ ​slopes​ ​are​ ​analysed​ ​in​ ​the​ ​form​ ​of​ ​Factor​ ​of​ ​Safety​ ​values,​ ​and​ ​slope​ ​stability improvement​ ​measures​ ​were​ ​proposed​ ​if​ ​slopes​ ​were​ ​deemed​ ​unstable.​ ​The​ ​seepage​ ​rates through​ ​embankment​ ​dams​ ​in​ ​The​ ​Reynoso​ ​Reservoir​ ​were​ ​also​ ​analysed​ ​using​ ​SEEP/W software,​ ​and​ ​a​ ​optimum​ ​cross-section​ ​was​ ​presented​ ​that​ ​limited​ ​seepage​ ​a​ ​maximum​ ​of 0.85m^3/day​ ​per​ ​metre​ ​length​ ​of​ ​the​ ​dam.​ ​Finally,​ ​the​ ​environmental​ ​and​ ​social​ ​impacts​ ​of reservoir​ ​construction​ ​were​ ​identified​ ​and​ ​assessed.​ ​Mitigation​ ​measures​ ​were​ ​proposed​ ​if needed.

Introduction

A​ ​conceptual​ ​design​ ​of​ ​the​ ​water​ ​storage​ ​reservoir​ ​and​ ​the​ ​water​ ​supply​ ​systems​ ​is​ ​to​ ​be​ ​created for​ ​the​ ​new​ ​township​ ​of​ ​Martinville​ ​-​ ​located​ ​in​ ​Western​ ​Tasmania,​ ​Australia.​ ​The​ ​proposed​ ​water storage​ ​reservoir​ ​has​ ​been​ ​named​ ​‘The​ ​Reynoso​ ​Reservoir’,​ ​which​ ​will​ ​supply​ ​water​ ​to​ ​200 households,​ ​15​ ​small​ ​business​ ​outlets​ ​and​ ​several​ ​dairy​ ​farms​ ​operating​ ​near​ ​Martinville.​ ​The conceptual​ ​design​ ​presented​ ​in​ ​this​ ​design​ ​report​ ​addresses​ ​all​ ​key​ ​aspects​ ​of​ ​facilities,​ ​satisfies Australian​ ​Standards,​ ​and​ ​meets​ ​all​ ​design​ ​requirements​ ​listed​ ​in​ ​the​ ​design​ ​brief.​ ​Extensive appendices​ ​with​ ​all​ ​calculations,​ ​software​ ​reports​ ​and​ ​additional​ ​information​ ​has​ ​been​ ​attached to​ ​this​ ​report​ ​as​ ​a​ ​reference​ ​for​ ​the​ ​reader.

3

Ground​ ​model

Site​ ​investigation​ ​data​ ​provided​ ​in​ ​Appendix​ ​A​ ​was​ ​used​ ​to​ ​construct​ ​a​ ​ground​ ​model​ ​of​ ​the​ ​soil to​ ​be​ ​used​ ​for​ ​The​ ​Reynoso​ ​Reservoir​ ​(see​ ​figure​ ​1).​ ​This​ ​ground​ ​model​ ​was​ ​created​ ​on​ ​Adobe Illustrator,​ ​and​ ​shows​ ​the​ ​ground​ ​surface​ ​level,​ ​ground​ ​layers​ ​with​ ​depths​ ​and​ ​the​ ​location​ ​of​ ​the groundwater​ ​table.​ ​It​ ​should​ ​be​ ​noted​ ​that​ ​the​ ​borehole​ ​widths​ ​are​ ​designed​ ​to​ ​be​ ​large​ ​enough to​ ​see​ ​a​ ​visual​ ​representation​ ​of​ ​the​ ​different​ ​soil​ ​layers​ ​at​ ​those​ ​points.​ ​Therefore,​ ​the​ ​width​ ​of the​ ​boreholes​ ​are​ ​not​ ​to​ ​scale,​ ​and​ ​the​ ​connections​ ​of​ ​lines​ ​between​ ​the​ ​boreholes​ ​are​ ​taken from​ ​the​ ​middle​ ​width​ ​instead​ ​of​ ​their​ ​edges.​ ​All​ ​other​ ​parts​ ​of​ ​the​ ​cross-section​ ​are​ ​to​ ​scale.

Figure​ ​1.​ ​Geological​ ​cross-section​ ​BH1-BH8

Water​ ​Storage​ ​and​ ​Catchment

The​ ​Reynoso​ ​Reservoir​ ​storage​ ​volume​ ​was​ ​then​ ​calculated​ ​on​ ​Excel​ ​spreadsheets.​ ​A​ ​catchment area​ ​was​ ​to​ ​be​ ​found​ ​that​ ​satisfied​ ​the​ ​required​ ​reliable​ ​water​ ​supply​ ​to​ ​Martinville​ ​and​ ​dairy farms.​ ​Precipitation​ ​and​ ​potential​ ​evapotranspiration​ ​data​ ​from​ ​Luncheon​ ​Hill​ ​(2010-2012)​ ​was used​ ​in​ ​the​ ​calculations.​ ​A​ ​minimum​ ​reservoir​ ​volume​ ​of​ ​1,000,000m^3​ ​was​ ​to​ ​be​ ​followed,​ ​and the​ ​initial​ ​water​ ​volume​ ​in​ ​the​ ​reservoir​ ​was​ ​2,500,000m^3.​ ​All​ ​data​ ​presented​ ​in​ ​the​ ​design​ ​brief was​ ​entered​ ​into​ ​the​ ​Excel​ ​spreadsheet​ ​(see​ ​figure​ ​2),​ ​which​ ​was​ ​then​ ​used​ ​in​ ​a​ ​series​ ​of equations​ ​(see​ ​Appendix​ ​G)​ ​throughout​ ​the​ ​columns​ ​seen​ ​in​ ​the​ ​spreadsheet​ ​in​ ​figure​ ​3.

4

Figure​ ​2.​ ​Inputted​ ​data​ ​into​ ​Excel​ ​spreadsheet​ ​for​ ​catchment​ ​area​ ​calculation

Figure​ ​3.​ ​Excel​ ​Spreadsheet​ ​for​ ​catchment​ ​area​ ​calculation

The​ ​column​ ​for​ ​water​ ​storage​ ​seen​ ​in​ ​figure​ ​3​ ​was​ ​then​ ​graphed​ ​against​ ​time,​ ​shown​ ​in​ ​figure​ ​4.

The​ ​catchment​ ​area​ ​data​ ​value​ ​shown​ ​in​ ​figure​ ​2​ ​was​ ​then​ ​adjusted​ ​until​ ​a​ ​desirable​ ​curve​ ​in​ ​the water​ ​storage​ ​vs.​ ​date​ ​graph​ ​was​ ​attained.​ ​A​ ​desirable​ ​graph​ ​involves​ ​water​ ​storage​ ​values​ ​that have​ ​a​ ​minimum​ ​of​ ​1,000,000m^3​ ​but​ ​that​ ​are​ ​also​ ​not​ ​too​ ​large​ ​due​ ​to​ ​cost​ ​reasons​ ​(a​ ​bigger catchment​ ​area​ ​will​ ​cost​ ​more​ ​to​ ​create​ ​and​ ​maintain).​ ​When​ ​a​ ​desirable​ ​graph​ ​shape​ ​was​ ​found, the​ ​minimum​ ​for​ ​the​ ​modelled​ ​water​ ​storage​ ​was​ ​1,340,761m^3.​ ​This​ ​means​ ​there​ ​is​ ​a​ ​substantial difference​ ​between​ ​the​ ​actual​ ​minimum​ ​and​ ​the​ ​allowed​ ​minimum​ ​of​ ​1,000,000m^3​ ​at​ ​all​ ​times​ ​in case​ ​of​ ​an​ ​emergency​ ​such​ ​as​ ​a​ ​drought.​ ​This​ ​desired​ ​water​ ​storage​ ​pattern​ ​gives​ ​a​ ​2.5km^2 catchment​ ​area​ ​to​ ​be​ ​used​ ​for​ ​the​ ​design.

5

Figure​ ​4.​ ​Water​ ​storage​ ​vs.​ ​date​ ​graph

Town​ ​Water​ ​Supply​ ​System

To​ ​propose​ ​a​ ​reliable​ ​and​ ​cost-effective​ ​system​ ​to​ ​supply​ ​water​ ​from​ ​the​ ​water​ ​storage​ ​of​ ​The Reynoso​ ​Reservoir​ ​to​ ​a​ ​water​ ​distribution​ ​station​ ​at​ ​Martinville​ ​the​ ​water​ ​consumption​ ​for households​ ​and​ ​businesses​ ​needed​ ​to​ ​be​ ​calculated​ ​(see​ ​Appendix​ ​A.1).​ ​The​ ​calculated​ ​water supply​ ​was​ ​then​ ​inputted​ ​into​ ​excel​ ​sheets​ ​that​ ​test​ ​the​ ​four​ ​potential​ ​pipe​ ​diameters​ ​for effectiveness​ ​(see​ ​Appendix​ ​B).​ ​Friction​ ​factors​ ​were​ ​calculated​ ​with​ ​an​ ​online​ ​friction​ ​factor calculator.​ ​Two​ ​separate​ ​excel​ ​sheets​ ​were​ ​created​ ​per​ ​diameter​ ​size,​ ​one​ ​for​ ​the​ ​water​ ​supply rates​ ​between​ ​the​ ​periods​ ​of​ ​April​ ​to​ ​October​ ​and​ ​the​ ​other​ ​for​ ​November​ ​to​ ​March.

The​ ​maximum​ ​required​ ​water​ ​supply​ ​for​ ​all​ ​the​ ​pipes​ ​was​ ​16.6m^3/hour​ ​for​ ​all​ ​piping​ ​diameters.

Calculated​ ​from​ ​the​ ​excel​ ​spreadsheets​ ​(see​ ​Appendix​ ​B),​ ​the​ ​required​ ​maximum​ ​total​ ​head​ ​for the​ ​diameters​ ​are​ ​as​ ​follows: 83mm:​ ​Overall​ ​head​ ​(m):​ ​114 101mm:​ ​Overall​ ​head​ ​(m):​ ​83.3 115mm:​ ​Overall​ ​head​ ​(m):​ ​74.5 129mm:​ ​Overall​ ​head​ ​(m):​ ​70.1

For​ ​the​ ​83mm​ ​diameter​ ​piping,​ ​two​ ​PLMGH​ ​3-11​ ​pumps​ ​would​ ​need​ ​to​ ​be​ ​in​ ​series​ ​to​ ​achieve​ ​a 114m​ ​total​ ​head​ ​due​ ​to​ ​the​ ​maximum​ ​total​ ​head​ ​that​ ​can​ ​be​ ​achieve​ ​by​ ​one​ ​pump​ ​is approximately​ ​105m.​ ​Pumps​ ​in​ ​series​ ​double​ ​the​ ​achieved​ ​total​ ​head​ ​of​ ​the​ ​system.​ ​With​ ​the pumps​ ​now​ ​in​ ​series,​ ​they​ ​would​ ​need​ ​to​ ​produce​ ​57m​ ​of​ ​head​ ​each,​ ​and​ ​therefore​ ​(according​ ​to the​ ​pump​ ​curve​ ​seen​ ​in​ ​Appendix​ ​F)​ ​will​ ​achieve​ ​a​ ​flow​ ​rate​ ​of​ ​4.7m^3/hour​ ​per​ ​pump.​ ​For​ ​the 16.6m^3/hour​ ​required​ ​flow​ ​rate,​ ​four​ ​parallel​ ​pumps​ ​would​ ​be​ ​needed​ ​(as​ ​parallel​ ​pumps​ ​double 6

the​ ​flow​ ​rate​ ​of​ ​the​ ​system).​ ​Therefore,​ ​a​ ​total​ ​of​ ​eight​ ​pumps​ ​(four​ ​parallel​ ​pipelines​ ​with​ ​two pumps​ ​in​ ​series​ ​on​ ​each)​ ​is​ ​the​ ​required​ ​configuration​ ​for​ ​the​ ​83mm​ ​diameter.

This​ ​process​ ​was​ ​repeated​ ​for​ ​the​ ​other​ ​three​ ​diameters.​ ​For​ ​the​ ​101mm​ ​piping,​ ​the​ ​pump​ ​curve shows​ ​a​ ​flow​ ​rate​ ​of​ ​3.2m^3/hour​ ​for​ ​a​ ​83.3m​ ​total​ ​head.​ ​Therefore,​ ​six​ ​pumps​ ​in​ ​parallel​ ​are needed​ ​for​ ​to​ ​achieve​ ​a​ ​16.6m^3/hour​ ​flow​ ​rate​ ​with​ ​no​ ​pumps​ ​in​ ​series.​ ​For​ ​the​ ​115mm​ ​piping, the​ ​pump​ ​curve​ ​shows​ ​a​ ​flow​ ​rate​ ​of​ ​3.8m^3/hour​ ​for​ ​a​ ​74.5m​ ​total​ ​head.​ ​Therefore,​ ​five​ ​pumps​ ​in parallel​ ​are​ ​needed​ ​for​ ​to​ ​achieve​ ​a​ ​16.6m^3/hour​ ​flow​ ​rate​ ​with​ ​no​ ​pumps​ ​in​ ​series.​ ​For​ ​the 129mm​ ​piping,​ ​the​ ​pump​ ​curve​ ​shows​ ​a​ ​flow​ ​rate​ ​of​ ​4.0m^3/hour​ ​for​ ​a​ ​70.1m​ ​total​ ​head.

Therefore,​ ​five​ ​pumps​ ​in​ ​parallel​ ​are​ ​needed​ ​for​ ​to​ ​achieve​ ​a​ ​16.6m^3/hour​ ​flow​ ​rate​ ​with​ ​no pumps​ ​in​ ​series.

Operating​ ​and​ ​installation​ ​costs​ ​were​ ​then​ ​compared​ ​between​ ​the​ ​four​ ​pipe​ ​sizes.​ ​The​ ​operating costs​ ​were​ ​taken​ ​from​ ​the​ ​spreadsheets​ ​in​ ​Appendix​ ​B,​ ​and​ ​the​ ​installation​ ​costs​ ​are​ ​as​ ​follows: Piping​ ​cost​ ​=​ ​length​ ​of​ ​piping​ ​(4000m)​ ​*​ ​piping​ ​cost​ ​(found​ ​in​ ​Appendix​ ​F) Excavation​ ​=​ ​length​ ​of​ ​piping​ ​*​ ​$50/m Pumping​ ​cost​ ​=​ ​number​ ​of​ ​pumps​ ​*​ ​$4000 The​ ​115mm​ ​piping​ ​was​ ​calculated​ ​to​ ​be​ ​the​ ​most​ ​cost-effective​ ​(see​ ​figure​ ​6)​ ​and​ ​was​ ​therefore selected​ ​for​ ​the​ ​proposed​ ​piping​ ​and​ ​configuration​ ​of​ ​pumps​ ​(see​ ​figure​ ​5).​ ​The​ ​overall installation​ ​cost​ ​of​ ​the​ ​proposed​ ​town​ ​water​ ​supply​ ​system​ ​is​ ​approximately​ ​$276000,​ ​and​ ​the operating​ ​cost​ ​of​ ​the​ ​system​ ​for​ ​20​ ​years​ ​is​ ​$69145.11.

Figure​ ​5.​ ​Proposed​ ​configuration​ ​of​ ​five​ ​pumps​ ​in​ ​parallel​ ​for​ ​115mm​ ​piping.

Figure​ ​6.​ ​Final​ ​operation​ ​and​ ​installation​ ​costs​ ​for​ ​piping​ ​diameters.

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Water​ ​Tower

A​ ​reliable​ ​and​ ​cost-effective​ ​design​ ​of​ ​a​ ​water​ ​tower​ ​to​ ​store​ ​water​ ​for​ ​Martinville​ ​for​ ​the​ ​cases​ ​of power​ ​outage​ ​or​ ​other​ ​emergencies​ ​is​ ​required.​ ​It​ ​should​ ​be​ ​able​ ​to​ ​store​ ​3-days​ ​supply​ ​of​ ​water for​ ​Martinville,​ ​which​ ​is​ ​calculated​ ​by​ ​multiplying​ ​the​ ​maximum​ ​total​ ​daily​ ​water​ ​supply​ ​(167.9m^3) from​ ​the​ ​water​ ​consumption​ ​spreadsheet​ ​(see​ ​Appendix​ ​A.1)​ ​by​ ​three,​ ​giving​ ​a​ ​total​ ​required water​ ​storage​ ​of​ ​503.7m^3.

Through​ ​research,​ ​it​ ​was​ ​found​ ​that​ ​a​ ​commonly​ ​used​ ​shape​ ​for​ ​a​ ​water​ ​tower​ ​tank​ ​is​ ​a​ ​cylinder with​ ​a​ ​hemispherical​ ​bottom​ ​(State​ ​of​ ​Michigan,​ ​2003​)​,​ ​therefore​ ​this​ ​design​ ​shape​ ​was​ ​selected.

The​ ​shape​ ​is​ ​ideal​ ​for​ ​a​ ​system​ ​where​ ​all​ ​the​ ​water​ ​will​ ​naturally​ ​flow​ ​to​ ​the​ ​bottom​ ​of​ ​the​ ​tank and​ ​no​ ​water​ ​will​ ​get​ ​stuck​ ​in​ ​the​ ​edges/corners​ ​of​ ​the​ ​tank​ ​interior.​ ​The​ ​dimensions​ ​for​ ​a hemispherical​ ​tank​ ​size​ ​from​ ​State​ ​of​ ​Michigan​ ​(2003​)​ ​were​ ​used​ ​as​ ​an​ ​initial​ ​point​ ​to​ ​calculate the​ ​tank’s​ ​dimensions​ ​and​ ​aimed​ ​to​ ​satisfy​ ​the​ ​minimum​ ​of​ ​503.7m^3​ ​volume.​ ​The​ ​actual​ ​volume was​ ​calculated​ ​through​ ​the​ ​following​ ​equations: Cylindrical​ ​element:​ ​Vc​ ​=​ ​(⅔)*π*(r^3)​ ​=​ ​(⅔)*π*(4^3)​ ​=​ ​134m^3 Hemispherical​ ​element:​ ​Vh​ ​=​ ​π*(r^2)*h​ ​=​ ​π*(4^2)*7.5​ ​=​ ​376.99m^3 Vtotal​ ​=​ ​Vc​ ​+​ ​Vh​ ​=​ ​510.99m^3 These​ ​proposed​ ​dimensions​ ​and​ ​volume​ ​are​ ​shown​ ​in​ ​figure​ ​7.

Figure​ ​7.​ ​Final​ ​design​ ​of​ ​water​ ​tower

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The​ ​material​ ​of​ ​a​ ​polyethylene​ ​water​ ​tank​ ​combined​ ​with​ ​a​ ​steel​ ​tower​ ​with​ ​steel​ ​bracing​ ​is selected​ ​after​ ​literature​ ​research.​ ​Polyethylene​ ​was​ ​chosen​ ​due​ ​to​ ​concrete​ ​water​ ​tanks​ ​being ‘very​ ​heavy​ ​and​ ​difficult​ ​to​ ​handle’​ ​(Bushmans​ ​Industrial,​ ​2016)​ ​and​ ​steel​ ​water​ ​tanks​ ​having​ ​the disadvantage​ ​of​ ​‘rust​ ​or​ ​corrosion’​ ​(Bushmans​ ​Industrial,​ ​2016).​ ​Therefore​ ​steel​ ​tanks​ ​require galvanising​ ​and​ ​‘extensive​ ​testing’​ ​to​ ​ensure​ ​the​ ​tank​ ​is​ ​watertight​ ​(Bushmans​ ​Industrial,​ ​2016).​ ​A polyethylene​ ​tank​ ​was​ ​selected​ ​due​ ​to​ ​easier​ ​installation​ ​(Team​ ​Poly,​ ​2017),​ ​as​ ​well​ ​as​ ​a​ ​lack​ ​of ‘incompatibility​ ​issues​ ​with​ ​dissimilar​ ​metals​ ​and​ ​metals​ ​that​ ​can​ ​cause​ ​corrosion’​ ​such​ ​as​ ​the steel​ ​tower​ ​(Team​ ​Poly,​ ​2017).​ ​This​ ​will​ ​decrease​ ​maintenance​ ​expenses.​ ​It​ ​should​ ​be​ ​noted​ ​that AS4766​ ​requires​ ​the​ ​thickness​ ​of​ ​the​ ​tank​ ​walls​ ​to​ ​be​ ​greater​ ​than​ ​4.5mm​ ​(Standards​ ​Australia, 2006)​ ​and​ ​therefore​ ​this​ ​thickness​ ​will​ ​be​ ​used​ ​for​ ​the​ ​design​ ​of​ ​this​ ​water​ ​tank.​ ​The​ ​typical​ ​tank life​ ​of​ ​a​ ​polyethylene​ ​water​ ​tank​ ​is​ ​15-20​ ​years​ ​(State​ ​of​ ​Michigan,​ ​2003​)​,​ ​which​ ​means​ ​the​ ​tank will​ ​need​ ​to​ ​be​ ​analysed​ ​at​ ​least​ ​every​ ​5​ ​years​ ​to​ ​see​ ​if​ ​it​ ​needs​ ​replacing​ ​or​ ​maintenance.

Lastly,​ ​it​ ​was​ ​considered​ ​that​ ​a​ ​minimum​ ​water​ ​pressure​ ​of​ ​250kPa​ ​has​ ​to​ ​be​ ​maintained​ ​at​ ​all households​ ​and​ ​business​ ​outlets,​ ​which​ ​gives​ ​a​ ​required​ ​change​ ​in​ ​elevation​ ​of​ ​26m​ ​from​ ​the water​ ​tower​ ​to​ ​Martinville: ∆P​ ​=​ ​ρ​ ​*​ ​g​ ​*​ ​∆h ∆P​ ​=​ ​998​ ​*​ ​9.8​ ​*​ ​26 ∆P​ ​=​ ​254.290​ ​kPa Therefore,​ ​because​ ​a​ ​total​ ​difference​ ​in​ ​elevation​ ​of​ ​26m​ ​is​ ​needed​ ​to​ ​achieve​ ​a​ ​water​ ​pressure of​ ​250kPa,​ ​and​ ​there​ ​being​ ​a​ ​minimum​ ​drop​ ​in​ ​elevation​ ​from​ ​the​ ​bottom​ ​of​ ​the​ ​tower​ ​to Martinville​ ​of​ ​15m,​ ​a​ ​height​ ​of​ ​11m​ ​is​ ​required​ ​for​ ​the​ ​tower​ ​of​ ​the​ ​water​ ​tank.

Water​ ​Supply​ ​System​ ​for​ ​Farms

A​ ​reliable​ ​and​ ​cost-effective​ ​system​ ​to​ ​supply​ ​water​ ​from​ ​the​ ​water​ ​storage​ ​of​ ​The​ ​Reynoso Reservoir​ ​to​ ​the​ ​farm​ ​water​ ​distribution​ ​centre​ ​is​ ​to​ ​also​ ​be​ ​proposed.​ ​This​ ​system​ ​needs​ ​to supply​ ​two​ ​days​ ​worth​ ​of​ ​water​ ​over​ ​a​ ​two​ ​hour​ ​period​ ​and​ ​will​ ​be​ ​organised​ ​through​ ​a​ ​main concrete​ ​open​ ​flow​ ​channel​ ​via​ ​two​ ​legs.​ ​From​ ​the​ ​water​ ​consumption​ ​spreadsheet​ ​(see Appendix​ ​A.2)​ ​a​ ​flow​ ​rate​ ​of​ ​3560.86m^3/hour​ ​per​ ​leg​ ​was​ ​calculated.

To​ ​propose​ ​a​ ​reliable​ ​and​ ​cost-effective​ ​design,​ ​four​ ​different​ ​cross-sections​ ​for​ ​the​ ​concrete channels​ ​were​ ​investigated:​ ​a​ ​semicircle,​ ​a​ ​right-angled​ ​triangle,​ ​a​ ​square​ ​and​ ​a​ ​trapezium​ ​(see Appendix​ ​C).​ ​The​ ​optimal​ ​height​ ​needed​ ​for​ ​the​ ​required​ ​flow​ ​rate​ ​of​ ​two​ ​days’​ ​supply​ ​for​ ​the farms​ ​is​ ​then​ ​calculated​ ​by​ ​solving​ ​for​ ​h​ ​in​ ​Manning’s​ ​equation: V​ ​=​ ​(1/n)*(Rh)^(⅔)*(S)^(½) Where: V​ ​is​ ​the​ ​velocity n​ ​is​ ​Manning’s​ ​roughness​ ​coefficient Rh​ ​is​ ​the​ ​hydraulic​ ​radius​ ​(area/wetted​ ​perimeter) S​ ​is​ ​the​ ​channel​ ​slope The​ ​trapezium​ ​cross-section​ ​was​ ​chosen​ ​as​ ​the​ ​most​ ​cost-effective,​ ​as​ ​it​ ​is​ ​able​ ​to​ ​satisfy​ ​the required​ ​flow​ ​rate​ ​with​ ​the​ ​lowest​ ​amount​ ​of​ ​excavation​ ​and​ ​concrete​ ​needed​ ​for​ ​construction (see​ ​figure​ ​8).​ ​In​ ​the​ ​final​ ​proposed​ ​design,​ ​h​ ​is​ ​7.2m​ ​for​ ​leg​ ​1​ ​and​ ​9.6m​ ​for​ ​leg​ ​2​ ​(see​ ​figure​ ​9​ ​and 10).​ ​An​ ​additional​ ​0.3m​ ​is​ ​included​ ​in​ ​the​ ​optimal​ ​heights​ ​of​ ​the​ ​cross-sections,​ ​creating​ ​a​ ​more reliable​ ​open​ ​channel​ ​flow​ ​system​ ​where​ ​water​ ​is​ ​less​ ​likely​ ​to​ ​splash​ ​out​ ​of​ ​the​ ​channel.​ ​The 9

total​ ​cost​ ​for​ ​the​ ​proposed​ ​designs​ ​is​ ​$281023​ ​for​ ​excavation​ ​and​ ​$111795​ ​for​ ​concrete​ ​costs​ ​(see figure​ ​8).

Figure​ ​9.​ ​Final​ ​proposed​ ​cross-section​ ​for​ ​leg​ ​1.

Figure​ ​8.​ ​Excavation​ ​and​ ​concrete​ ​usage​ ​for​ ​open-channel​ ​flow​ ​system​ ​cross-sections.

Figure​ ​10.​ ​Final​ ​proposed​ ​cross-section​ ​for​ ​leg​ ​2.

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Stability​ ​of​ ​Existing​ ​Slopes

The​ ​program​ ​SEEP/W​ ​was​ ​used​ ​to​ ​model​ ​both​ ​slopes​ ​before​ ​construction​ ​and​ ​find​ ​critical​ ​failure surfaces.​ ​All​ ​geometric​ ​characteristics​ ​of​ ​the​ ​slopes​ ​have​ ​been​ ​modelled​ ​from​ ​the​ ​geological cross-section​ ​in​ ​the​ ​first​ ​part​ ​of​ ​this​ ​report,​ ​and​ ​it​ ​should​ ​be​ ​mentioned​ ​that​ ​a​ ​diameter​ ​of​ ​16mm for​ ​the​ ​boreholes​ ​was​ ​used​ ​(IndustrySearch,​ ​2017).​ ​The​ ​minimum​ ​factor​ ​of​ ​safeties​ ​(FoS)​ ​against sliding​ ​were​ ​found​ ​using​ ​Bishop’s​ ​Grid​ ​and​ ​Radius​ ​method​ ​and​ ​are​ ​as​ ​follows: Left​ ​slope​ ​before​ ​construction:​ ​1.148 Right​ ​slope​ ​after​ ​construction:​ ​0.967 The​ ​critical​ ​failure​ ​surfaces​ ​for​ ​both​ ​slopes​ ​before​ ​construction​ ​can​ ​be​ ​found​ ​in​ ​Appendix​ ​D.2​ ​and D.3.​ ​Both​ ​of​ ​these​ ​minimum​ ​FoS’s​ ​do​ ​not​ ​satisfy​ ​a​ ​FoS​ ​of​ ​more​ ​than​ ​1.2,​ ​therefore​ ​before​ ​the construction​ ​of​ ​The​ ​Reynoso​ ​Reservoir,​ ​both​ ​slopes​ ​are​ ​considered​ ​to​ ​be​ ​unstable.

The​ ​right​ ​slope​ ​of​ ​The​ ​Reynoso​ ​Reservoir​ ​cross-section​ ​before​ ​construction​ ​was​ ​then​ ​chosen​ ​to perform​ ​hand​ ​calculations​ ​(using​ ​Bishop’s​ ​Method)​ ​to​ ​compare​ ​with​ ​the​ ​SLOPE/W​ ​results,​ ​which can​ ​be​ ​seen​ ​in​ ​figure​ ​11.

Figure​ ​11.​ ​Bishop’s​ ​Method​ ​for​ ​critical​ ​slip​ ​surface​ ​for​ ​right​ ​slope​ ​before​ ​construction

In​ ​the​ ​cross-section​ ​in​ ​figure​ ​11​ ​the​ ​slip​ ​surface​ ​is​ ​divided​ ​into​ ​6​ ​slices​ ​with​ ​even​ ​widths​ ​of​ ​5m.​ ​The area​ ​of​ ​soil​ ​1​ ​(stiff​ ​silty​ ​clay)​ ​and​ ​soil​ ​2​ ​(soft​ ​silty​ ​clay)​ ​in​ ​each​ ​slice,​ ​each​ ​slice’s​ ​base​ ​angle,​ ​and the​ ​height​ ​of​ ​the​ ​water​ ​table​ ​to​ ​the​ ​base​ ​of​ ​each​ ​slice​ ​were​ ​all​ ​measured.​ ​From​ ​this,​ ​the​ ​base angle​ ​(α),​ ​cohesion​ ​(c’),​ ​friction​ ​angle​ ​(φ’),​ ​slice​ ​weight​ ​(W),​ ​slice​ ​width​ ​(b)​ ​and​ ​pressure​ ​on​ ​the base​ ​of​ ​the​ ​slice​ ​(u​ ​=​ ​height​ ​from​ ​water​ ​table*gravitational​ ​forces)​ ​were​ ​entered​ ​into​ ​the​ ​excel spreadsheet​ ​seen​ ​in​ ​figure​ ​12.​ ​Calculations​ ​for​ ​the​ ​FoS​ ​were​ ​then​ ​performed​ ​through​ ​the​ ​solver function​ ​on​ ​excel,​ ​which​ ​aimed​ ​to​ ​reduce​ ​the​ ​‘difference’​ ​to​ ​zero​ ​between​ ​the​ ​guessed​ ​and calculated​ ​FoS​ ​excel​ ​boxes.​ ​This​ ​gave​ ​a​ ​calculated​ ​FoS​ ​of​ ​0.94.

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Figure​ ​12.​ ​Excel​ ​spreadsheet​ ​for​ ​calculated​ ​FoS

SLOPE/W​ ​analysis​ ​produced​ ​an​ ​FoS​ ​of​ ​0.966​ ​for​ ​this​ ​particular​ ​slope,​ ​therefore​ ​the​ ​difference between​ ​the​ ​two​ ​values​ ​are​ ​minor​ ​at​ ​a​ ​value​ ​of​ ​0.026.​ ​It’s​ ​safe​ ​to​ ​assume​ ​that​ ​the hand-calculations​ ​of​ ​Bishop’s​ ​Method​ ​are​ ​quite​ ​accurate,​ ​but​ ​do​ ​not​ ​give​ ​completely​ ​accurate results​ ​due​ ​to​ ​human​ ​error,​ ​as​ ​well​ ​as​ ​the​ ​simplification​ ​of​ ​the​ ​base​ ​angle​ ​and​ ​measurements​ ​of the​ ​slices’​ ​dimensions​ ​within​ ​the​ ​method’s​ ​steps.

Modelling​ ​of​ ​the​ ​slopes​ ​after​ ​construction​ ​of​ ​The​ ​Reynoso​ ​Reservoir​ ​was​ ​then​ ​performed​ ​on SEEP/W.​ ​This​ ​construction​ ​involved​ ​the​ ​valley​ ​being​ ​filled​ ​up​ ​with​ ​water​ ​at​ ​a​ ​maximum​ ​of​ ​213m from​ ​RL.​ ​The​ ​original​ ​slopes​ ​were​ ​used​ ​as​ ​a​ ​starting​ ​point,​ ​with​ ​the​ ​piezometric​ ​line​ ​then readjusted​ ​to​ ​model​ ​the​ ​reservoir​ ​construction.​ ​Bishop’s​ ​Grid​ ​and​ ​Radius​ ​method​ ​was​ ​then​ ​used to​ ​find​ ​the​ ​new​ ​FoS​ ​values​ ​for​ ​both​ ​slopes: Left​ ​side​ ​slope​ ​after​ ​construction:​ ​1.205 Right​ ​side​ ​slope​ ​after​ ​construction:​ ​1.144 The​ ​critical​ ​failure​ ​surfaces​ ​for​ ​both​ ​slopes​ ​after​ ​construction​ ​can​ ​be​ ​found​ ​in​ ​Appendix​ ​D.4​ ​and D.5.​ ​The​ ​pressure​ ​force​ ​on​ ​the​ ​higher​ ​water​ ​level​ ​has​ ​stabilized​ ​the​ ​slopes​ ​slightly,​ ​with​ ​the​ ​left side​ ​now​ ​becoming​ ​stable​ ​(a​ ​FoS​ ​above​ ​1.2).​ ​However,​ ​the​ ​right​ ​slope​ ​is​ ​still​ ​significantly​ ​under the​ ​required​ ​1.2​ ​FoS.

Using​ ​unit​ ​costs​ ​of​ ​available​ ​slope​ ​stability​ ​improvement​ ​measures​ ​(see​ ​Appendix​ ​F),​ ​the​ ​three improvement​ ​measure​ ​options​ ​(excavation​ ​and​ ​local​ ​re-compaction​ ​of​ ​soil,​ ​excavation​ ​and removal​ ​of​ ​soil,​ ​and​ ​imported​ ​fill)​ ​were​ ​compared​ ​to​ ​identify​ ​the​ ​most​ ​cost-effective.

The​ ​slopes​ ​were​ ​modified​ ​before​ ​construction​ ​due​ ​to​ ​constructability​ ​(as​ ​it’s​ ​increasingly​ ​difficult to​ ​construct​ ​the​ ​modifications​ ​of​ ​the​ ​reservoir​ ​slopes​ ​when​ ​the​ ​reservoir​ ​is​ ​full​ ​of​ ​water).

Additionally,​ ​the​ ​modifications​ ​were​ ​constructed​ ​to​ ​increase​ ​the​ ​FoS’s​ ​of​ ​the​ ​slopes​ ​before construction​ ​of​ ​the​ ​dam​ ​because​ ​the​ ​construction​ ​of​ ​the​ ​dam​ ​(reservoir​ ​being​ ​filled​ ​with​ ​water) will​ ​only​ ​increase​ ​the​ ​stability​ ​of​ ​the​ ​slopes.​ ​Therefore,​ ​if​ ​a​ ​FoS​ ​of​ ​1.2​ ​is​ ​satisfied​ ​before construction​ ​then​ ​the​ ​slopes​ ​will​ ​always​ ​remain​ ​stable.

Firstly,​ ​the​ ​left​ ​slope​ ​was​ ​first​ ​modified​ ​to​ ​satisfy​ ​a​ ​1.2​ ​FoS.​ ​Excavation​ ​and​ ​fill​ ​was​ ​considered (see​ ​figure​ ​13)​ ​which​ ​resulted​ ​in​ ​a​ ​FoS​ ​of​ ​1.208​ ​(stable)​ ​by​ ​excavating​ ​and​ ​filling​ ​4.9651m^2​ ​of​ ​soil and​ ​excavating​ ​an​ ​extra​ ​0.2149m^2.​ ​The​ ​total​ ​cost​ ​would​ ​be​ ​$123.46/m​ ​(see​ ​figure​ ​14).​ ​The improvement​ ​measure​ ​of​ ​excavation​ ​and​ ​removal​ ​of​ ​soil​ ​was​ ​then​ ​calculated​ ​(see​ ​Appendix​ ​D.6), which​ ​was​ ​not​ ​possible​ ​to​ ​achieve​ ​a​ ​FoS​ ​of​ ​more​ ​than​ ​1.2​ ​for​ ​the​ ​left​ ​slope​ ​without​ ​excavating 12

below​ ​the​ ​water-table​ ​(impossible​ ​due​ ​to​ ​water​ ​coming​ ​out​ ​of​ ​the​ ​soil​ ​resulting​ ​in​ ​instability​ ​of​ ​the slope).​ ​Imported​ ​fill​ ​was​ ​also​ ​considered,​ ​however​ ​even​ ​though​ ​the​ ​modification​ ​was geometrically​ ​possible,​ ​the​ ​cost​ ​to​ ​increase​ ​the​ ​FoS​ ​to​ ​1.2​ ​was​ ​significantly​ ​more​ ​than​ ​the​ ​other options​ ​(see​ ​figure​ ​14).​ ​Therefore,​ ​excavation​ ​and​ ​re-compaction​ ​will​ ​chosen​ ​as​ ​the​ ​slope​ ​stability improvement​ ​measure​ ​for​ ​the​ ​left​ ​hand​ ​slope.​ ​This​ ​is​ ​not​ ​only​ ​because​ ​of​ ​cost-effectiveness,​ ​but also​ ​due​ ​to​ ​a​ ​smaller​ ​reduction​ ​in​ ​the​ ​volume​ ​of​ ​the​ ​future​ ​reservoir.

Figure​ ​13.​ ​Excavation​ ​and​ ​fill​ ​modification​ ​of​ ​left​ ​slope

Figure​ ​14.​ ​Comparison​ ​of​ ​costs​ ​for​ ​modification​ ​for​ ​left​ ​slope

Next,​ ​the​ ​right​ ​slope​ ​was​ ​then​ ​modified​ ​to​ ​satisfy​ ​a​ ​1.2​ ​FoS.​ ​Excavation​ ​and​ ​fill​ ​was​ ​considered (see​ ​figure​ ​15),​ ​which​ ​produced​ ​a​ ​FoS​ ​of​ ​1.211​ ​(stable)​ ​by​ ​excavating​ ​and​ ​filling​ ​23.81m^2​ ​of​ ​soil and​ ​excavating​ ​an​ ​extra​ ​0.3m^2.​ ​The​ ​total​ ​cost​ ​is​ ​$577.44/m​ ​(see​ ​figure​ ​16).​ ​The​ ​improvement measure​ ​of​ ​excavation​ ​and​ ​removal​ ​of​ ​soil​ ​was​ ​then​ ​calculated​ ​(see​ ​Appendix​ ​D.10),​ ​which​ ​was not​ ​possible​ ​to​ ​achieve​ ​a​ ​FoS​ ​of​ ​more​ ​than​ ​1.2​ ​for​ ​the​ ​left​ ​slope​ ​without​ ​excavating​ ​below​ ​the water-table.​ ​Imported​ ​fill​ ​was​ ​also​ ​considered,​ ​however​ ​even​ ​though​ ​the​ ​modification​ ​was geometrically​ ​possible,​ ​the​ ​cost​ ​to​ ​increase​ ​the​ ​FoS​ ​to​ ​1.2​ ​was​ ​significantly​ ​more​ ​than​ ​the​ ​other options​ ​(see​ ​figure​ ​16).​ ​Therefore,​ ​excavation​ ​and​ ​re-compaction​ ​was​ ​chosen​ ​as​ ​the​ ​slope stability​ ​improvement​ ​measure​ ​for​ ​the​ ​right​ ​hand​ ​slope.

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Figure​ ​15.​ ​Excavation​ ​and​ ​fill​ ​modification​ ​of​ ​right​ ​slope

Figure​ ​16.​ ​Comparison​ ​of​ ​costs​ ​for​ ​modification​ ​for​ ​right​ ​slope

Embankment​ ​Dam Firstly,​ ​the​ ​estimated​ ​daily​ ​seepage​ ​rates​ ​through​ ​the​ ​dams​ ​and​ ​underlying​ ​soil​ ​for​ ​the​ ​two preliminary​ ​design​ ​options​ ​of​ ​the​ ​dam​ ​cross-section​ ​(see​ ​Appendix​ ​F)​ ​were​ ​analysed​ ​using SEEP/W​ ​software.​ ​The​ ​first​ ​preliminary​ ​design​ ​option​ ​is​ ​a​ ​dam​ ​without​ ​a​ ​drain,​ ​which​ ​can​ ​be​ ​seen in​ ​figure​ ​17.​ ​SEEP/W​ ​estimated​ ​the​ ​daily​ ​seepage​ ​rate​ ​to​ ​be​ ​3.15m^3/day.​ ​Secondly,​ ​the​ ​same geometric​ ​structure​ ​of​ ​the​ ​dam​ ​with​ ​an​ ​added​ ​drain​ ​was​ ​analysed​ ​(see​ ​figure​ ​18),​ ​giving​ ​a significant​ ​increase​ ​in​ ​daily​ ​seepage​ ​rate​ ​to​ ​5.4m^3/day.​ ​Refer​ ​to​ ​figure​ ​19​ ​for​ ​summary​ ​of seepage​ ​rates.

When​ ​a​ ​drain​ ​is​ ​included​ ​in​ ​the​ ​design,​ ​a​ ​mesh​ ​of​ ​0.1m​ ​length​ ​is​ ​placed​ ​around​ ​the​ ​barrier​ ​instead of​ ​the​ ​universal​ ​1m​ ​mesh​ ​which​ ​is​ ​placed​ ​throughout​ ​the​ ​rest​ ​of​ ​the​ ​dam.​ ​This​ ​is​ ​because​ ​the pressure​ ​gradient​ ​increases​ ​quickly​ ​towards​ ​the​ ​area​ ​of​ ​the​ ​drain​ ​as​ ​the​ ​water​ ​leaves​ ​the​ ​body​ ​of the​ ​dam​ ​(pressure​ ​increases).​ ​A​ ​finer​ ​mesh​ ​is​ ​placed​ ​at​ ​the​ ​drain​ ​as​ ​it​ ​will​ ​be​ ​more​ ​accurate​ ​in picking​ ​up​ ​changes​ ​in​ ​the​ ​pressure​ ​gradient.​ ​A​ ​1m​ ​mesh​ ​can​ ​be​ ​placed​ ​elsewhere,​ ​as​ ​the pressure​ ​gradient​ ​is​ ​more​ ​gradual​ ​and​ ​a​ ​larger​ ​mesh​ ​can​ ​more​ ​accurately​ ​pick​ ​up​ ​the​ ​pressure gradient.

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Figure​ ​17.​ ​Preliminary​ ​design​ ​option​ ​with​ ​no​ ​drain

Figure​ ​18.​ ​Preliminary​ ​design​ ​option​ ​with​ ​drain

Figure​ ​19.​ ​Summary​ ​of​ ​seepage​ ​rates​ ​for​ ​variety​ ​of​ ​dam​ ​designs

A​ ​recommendation​ ​for​ ​construction​ ​of​ ​the​ ​dam​ ​was​ ​then​ ​found​ ​through​ ​consideration​ ​of​ ​different sized​ ​cores.​ ​Two​ ​core​ ​materials​ ​were​ ​available​ ​for​ ​use:​ ​a​ ​clayey​ ​core​ ​material​ ​of​ ​medium hydraulic​ ​conductivity​ ​(LHC​ ​core)​ ​or​ ​a​ ​clayey​ ​core​ ​material​ ​of​ ​low​ ​hydraulic​ ​conductivity​ ​(MHC core).

For​ ​the​ ​design​ ​option​ ​without​ ​a​ ​drain,​ ​the​ ​cost​ ​when​ ​using​ ​the​ ​MHC​ ​core​ ​is​ ​significantly​ ​higher than​ ​when​ ​using​ ​the​ ​LHC​ ​core​ ​(see​ ​figure​ ​19).​ ​The​ ​LCH​ ​core​ ​also​ ​gives​ ​a​ ​more​ ​optimal​ ​flow​ ​rate, therefore​ ​the​ ​MHC​ ​core​ ​will​ ​not​ ​be​ ​considered​ ​for​ ​the​ ​final​ ​design​ ​option​ ​of​ ​the​ ​dam.​ ​The​ ​design 15

option​ ​involving​ ​no​ ​drain​ ​will​ ​not​ ​be​ ​used​ ​due​ ​to​ ​safety​ ​issues​ ​of​ ​piping,​ ​as​ ​drainage​ ​systems significantly​ ​lower​ ​the​ ​possibility​ ​of​ ​failure​ ​due​ ​to​ ​piping​ ​or​ ​erosion​ ​of​ ​soil.​ ​Additionally,​ ​it​ ​should be​ ​noted​ ​that​ ​additional​ ​drain​ ​material​ ​is​ ​an​ ​option​ ​to​ ​decrease​ ​the​ ​seepage​ ​rate,​ ​but​ ​will​ ​not​ ​be further​ ​looked​ ​at​ ​as​ ​it​ ​affects​ ​the​ ​flow​ ​rate​ ​by​ ​increasing​ ​it,​ ​and​ ​therefore​ ​only​ ​the​ ​initial​ ​drainage from​ ​the​ ​second​ ​preliminary​ ​design​ ​option​ ​will​ ​be​ ​used.

Therefore,​ ​the​ ​design​ ​option​ ​with​ ​the​ ​initial​ ​drain​ ​design​ ​and​ ​a​ ​LHC​ ​core​ ​is​ ​selected.​ ​Different sized​ ​LHC​ ​cores​ ​were​ ​considered​ ​and​ ​it​ ​was​ ​found​ ​that​ ​the​ ​minimum​ ​amount​ ​of​ ​material​ ​needed to​ ​achieve​ ​the​ ​maximum​ ​daily​ ​seepage​ ​rate​ ​was​ ​132m^2​ ​(see​ ​figure​ ​20​ ​and​ ​21).​ ​The​ ​total​ ​cost​ ​of this​ ​design​ ​is​ ​$5544/m​ ​length​ ​of​ ​the​ ​dam,​ ​which​ ​is​ ​more​ ​cost-effective​ ​than​ ​using​ ​the​ ​MCH​ ​core.

It​ ​is​ ​also​ ​a​ ​safe​ ​design​ ​option​ ​as​ ​the​ ​likelihood​ ​of​ ​piping​ ​failure​ ​has​ ​been​ ​avoided​ ​through​ ​use​ ​of a​ ​drain​ ​system.​ ​This​ ​design​ ​reduces​ ​the​ ​flow​ ​rate​ ​to​ ​a​ ​desired​ ​0.83m^3/day​ ​(see​ ​figure​ ​19).

Figure​ ​20.​ ​Final​ ​conceptual​ ​design​ ​for​ ​embankment​ ​dam

Figure​ ​21.​ ​Seepage​ ​analysis​ ​of​ ​final​ ​conceptual​ ​design​ ​for​ ​embankment​ ​dam

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Environmental​ ​and​ ​Social​ ​Impact​ ​Assessment

Lastly,​ ​potential​ ​environmental​ ​and​ ​social​ ​impacts​ ​of​ ​construction​ ​and​ ​operation​ ​of​ ​the​ ​water storage​ ​in​ ​The​ ​Reynoso​ ​Reservoir​ ​are​ ​identified​ ​and​ ​their​ ​mitigations​ ​outlined​ ​in​ ​table​ ​1.

Item

Impact​ ​Description

Proposed​ ​mitigation​ ​measures​ ​(if necessary)

Local​ ​regional infrastructure (social)

Increased​ ​access​ ​to​ ​water​ ​for ‘domestic​ ​and​ ​industrial​ ​purposes’ (Tortajada,​ ​Altinbilek​ ​and​ ​Biswas, 2014).​ ​This​ ​stability​ ​of​ ​water​ ​leads​ ​to positive​ ​social​ ​changes​ ​and​ ​new opportunities​ ​for​ ​further development​ ​of​ ​the​ ​surrounding area.​ ​This​ ​regional​ ​development which​ ​will​ ​ultimately​ ​improve​ ​the quality​ ​of​ ​life​ ​(Tortajada,​ ​Altinbilek and​ ​Biswas,​ ​2014).

Economics (social)

Majority​ ​of​ ​economic​ ​impacts​ ​are positive,​ ​as​ ​it​ ​will​ ​increase​ ​job opportunities​ ​during​ ​construction and​ ​maintenance/running​ ​of​ ​the reservoir.​ ​Reservoir​ ​construction demands​ ​‘large​ ​amounts​ ​of​ ​skilled and​ ​unskilled​ ​labor’​ ​(Manatunge, Priyadarshana​ ​and​ ​Nakayama,​ ​2017) which​ ​improves​ ​the​ ​local community’s​ ​economic​ ​growth.

However,​ ​many​ ​construction​ ​jobs​ ​will be​ ​of​ ​a​ ​‘temporary​ ​nature’​ ​and​ ​will last​ ​for​ ​under​ ​a​ ​decade​ ​(Haws,​ ​1985).

A​ ​stable​ ​water​ ​supply​ ​for​ ​irrigation​ ​in a​ ​regulated​ ​manner​ ​will​ ​promote efficient​ ​agricultural​ ​production (Tortajada,​ ​Altinbilek​ ​and​ ​Biswas, 2014).​ ​Additionally,​ ​the​ ​chance​ ​of floods​ ​and​ ​droughts​ ​will​ ​decrease​ ​by storing​ ​rainwater​ ​(Valdiya,​ ​2015).

To​ ​relieve​ ​post​ ​project​ ​migration, it’s​ ​recommended​ ​that​ ​other​ ​new industries​ ​surrounding​ ​the reservoir​ ​are​ ​constructed post-construction​ ​of​ ​the​ ​reservoir (Haws,​ ​1985).​ ​This​ ​will​ ​continue local​ ​economic​ ​prospects​ ​and result​ ​in​ ​stronger​ ​job​ ​stability.

Water​ ​flux (environmental)

The​ ​altering​ ​of​ ​water​ ​temperature, chemistry,​ ​flow,​ ​pressure​ ​and coverage​ ​will​ ​upset​ ​the​ ​equilibrium of​ ​the​ ​ecosystems​ ​in​ ​the​ ​surrounding areas​ ​of​ ​the​ ​reservoir​ ​(Valdiya,​ ​2015).

Upstream​ ​and​ ​downstream residents​ ​must​ ​adapt​ ​to​ ​new​ ​flow patterns.​ ​Residents​ ​should​ ​not​ ​rule out​ ​the​ ​chance​ ​of​ ​flooding completely.​ ​Residents​ ​of 17

There​ ​will​ ​also​ ​be​ ​reduced​ ​runoff and​ ​reduction​ ​in​ ​groundwater recharge​ ​in​ ​the​ ​dammed​ ​areas (Manatunge,​ ​Priyadarshana​ ​and Nakayama,​ ​2017).

Flow​ ​of​ ​any​ ​present​ ​rivers​ ​will dramatically​ ​be​ ​impacted,​ ​with​ ​water velocity​ ​increasing​ ​below​ ​the​ ​dam and​ ​past​ ​annual​ ​cycles​ ​of​ ​discharge changing​ ​significantly​ ​(Manatunge, Priyadarshana​ ​and​ ​Nakayama,​ ​2017).

Upstream​ ​and​ ​downstream​ ​residents can​ ​be​ ​‘adversely’​ ​affected​ ​while living​ ​in​ ​distant​ ​towns​ ​(Valdiya,​ ​2015).

connecting​ ​rivers​ ​to​ ​the valley/reservoir​ ​area​ ​should​ ​keep riverbeds​ ​clear​ ​and​ ​banks​ ​in​ ​good order​ ​(Haws,​ ​1985).​ ​Signs​ ​should be​ ​invested​ ​in​ ​to​ ​remind​ ​residents of​ ​potential​ ​flooding​ ​in​ ​riverbank areas​ ​even​ ​though​ ​it​ ​is​ ​rare.

Authorities​ ​should​ ​produce​ ​an emergency​ ​flooding​ ​evacuation plan​ ​incase​ ​of​ ​flooding,​ ​and downstream​ ​and​ ​upstream residents​ ​should​ ​have​ ​access​ ​to these​ ​plans​ ​(Haws,​ ​1985).

Biodiversity​ ​of surrounding environment (environmental)

Usually​ ​connecting​ ​river​ ​channels are​ ​narrowed​ ​and​ ​become​ ​‘overrun with​ ​vegetation’​ ​(Manatunge, Priyadarshana​ ​and​ ​Nakayama,​ ​2017).

Additionally,​ ​submergence​ ​of​ ​forests within​ ​the​ ​reservoir​ ​area​ ​also​ ​occurs.

This​ ​causes​ ​wildlife​ ​to​ ​flee​ ​the​ ​area due​ ​to​ ​habitat​ ​loss​ ​(Valdiya,​ ​2015).

Increased​ ​human​ ​activities​ ​in​ ​the area​ ​such​ ​as​ ​‘intensive​ ​agriculture, industries,​ ​and​ ​increased​ ​pressure on​ ​land’​ ​(Manatunge,​ ​Priyadarshana and​ ​Nakayama,​ ​2017)​ ​also​ ​impact​ ​the physical​ ​habitat,​ ​including​ ​fauna​ ​and flora.​ ​Changes​ ​in​ ​the​ ​water​ ​flows upstream​ ​and​ ​downstream​ ​also negatively​ ​affect​ ​ecosystems​ ​in connected​ ​areas​ ​(Manatunge, Priyadarshana​ ​and​ ​Nakayama,​ ​2017).

Analysis​ ​of​ ​the​ ​current​ ​ecosystem is​ ​to​ ​be​ ​completed,​ ​and​ ​a​ ​plant​ ​and animals​ ​protection​ ​management plan​ ​should​ ​be​ ​written​ ​up pre-construction​ ​with​ ​the​ ​aim​ ​of minimal​ ​impact.

Environmental​ ​impacts​ ​are​ ​to​ ​be assessed​ ​during​ ​and​ ​after construction​ ​regularly​ ​to​ ​check​ ​that management​ ​plan​ ​is​ ​followed.​ ​This assessment​ ​will​ ​include: ● Investigating​ ​the​ ​landscape (Wang​ ​et​ ​al.,​ ​2011). ● Analysing​ ​the​ ​efficiency​ ​of protective​ ​mitigations (Wang​ ​et​ ​al.,​ ​2011). ● Creating​ ​better​ ​mitigations if​ ​standards​ ​are​ ​not​ ​being met​ ​(Wang​ ​et​ ​al.,​ ​2011).

Health​ ​and welfare (environmental/so cial)

Nutrients​ ​are​ ​entrapped​ ​in​ ​the reservoir​ ​water​ ​body,​ ​which​ ​can cause​ ​high​ ​eutrophication​ ​and ‘growth​ ​of​ ​aquatic​ ​weeds’ (Manatunge,​ ​Priyadarshana​ ​and Nakayama,​ ​2017).​ ​There​ ​is deterioration​ ​of​ ​water​ ​quality​ ​due​ ​to decay​ ​of​ ​organic​ ​matter​ ​and​ ​human pollution,​ ​which​ ​also​ ​supports​ ​growth of​ ​organisms​ ​feeding​ ​on​ ​these

Before​ ​construction​ ​of​ ​the reservoir,​ ​an​ ​investigation​ ​into​ ​any potential​ ​human​ ​diseases​ ​within the​ ​area​ ​is​ ​conducted​ ​(Haws, 1985).​ ​A​ ​new​ ​health​ ​system located​ ​within​ ​the​ ​township​ ​should be​ ​constructed.​ ​Medicines, vaccines​ ​and​ ​other​ ​related​ ​health products​ ​should​ ​be​ ​stocked​ ​at​ ​this health​ ​system.

18

Erosion​ ​changes (environmental)

products​ ​(Valdiya,​ ​2015).​ ​Due​ ​to​ ​the increase​ ​in​ ​human​ ​population​ ​there will​ ​also​ ​be​ ​an​ ​increase​ ​in​ ​solid waste​ ​and​ ​wastewater.​ ​This​ ​creates a​ ​habitat​ ​where​ ​parasites​ ​and​ ​germs thrive​ ​as​ ​large​ ​bodies​ ​of​ ​water​ ​can easily​ ​transmit​ ​human​ ​diseases (Haws,​ ​1985).

A​ ​pollution​ ​management​ ​plan​ ​will combat​ ​the​ ​impacts​ ​of​ ​chemicals and​ ​sewage​ ​waste​ ​in​ ​the​ ​reservoir.

Agricultural​ ​uses​ ​of​ ​pesticides​ ​and fertilisers​ ​should​ ​always​ ​be recorded​ ​and​ ​observed​ ​by authorities,​ ​with​ ​any​ ​chemicals​ ​that can​ ​cause​ ​harm​ ​to​ ​humans​ ​banned (Haws,​ ​1985).

Increased​ ​erosion​ ​and​ ​scouring​ ​of riverbeds​ ​in​ ​downstream​ ​areas​ ​will occur​ ​(Manatunge,​ ​Priyadarshana and​ ​Nakayama,​ ​2017)​ ​as​ ​sediment transportation​ ​is​ ​greatly​ ​impacted.

This​ ​occurs​ ​due​ ​to​ ​the​ ​water released​ ​from​ ​the​ ​reservoir​ ​wanting to​ ​‘satisfy​ ​its​ ​capacity​ ​of​ ​bed​ ​material’ (Valdiya,​ ​2015).

The​ ​construction​ ​of​ ​the​ ​reservoir​ ​will cause​ ​the​ ​water​ ​table​ ​to​ ​‘rise​ ​and​ ​fall drastically’​ ​which​ ​ultimately​ ​reduces the​ ​shear​ ​strength​ ​of​ ​the​ ​soil​ ​and rocks​ ​in​ ​the​ ​slopes​ ​of​ ​the​ ​reservoir (Valdiya,​ ​2015).​ ​This​ ​could​ ​cause​ ​a failure​ ​of​ ​the​ ​reservoir​ ​slopes, resulting​ ​in​ ​a​ ​landslide​ ​‘particularly​ ​is the​ ​slopes​ ​are​ ​already​ ​in​ ​a​ ​state​ ​of instability’​ ​(Valdiya,​ ​2015).

The​ ​chance​ ​of​ ​erosion​ ​occurring​ ​in the​ ​water​ ​channels​ ​between​ ​the reservoir​ ​and​ ​the​ ​township​ ​and farmlands​ ​will​ ​be​ ​mitigated​ ​by using​ ​a​ ​piping​ ​system​ ​for​ ​the township​ ​and​ ​a​ ​open-channel water​ ​system​ ​with​ ​a​ ​concrete​ ​bed for​ ​the​ ​farm​ ​water​ ​supply​ ​system.

This​ ​ensures​ ​no​ ​erosion​ ​of riverbeds/soil​ ​in​ ​the​ ​surrounding environment​ ​will​ ​occur.

This​ ​most​ ​critical​ ​slip​ ​surfaces​ ​of the​ ​reservoir​ ​have​ ​been​ ​analysed pre-construction​ ​and​ ​slope​ ​stability mitigations​ ​presented​ ​in​ ​this​ ​report should​ ​be​ ​followed​ ​to​ ​ensure​ ​no failures​ ​of​ ​the​ ​slopes​ ​will​ ​occur.

Table​ ​1.​ ​Potential​ ​environmental​ ​and​ ​social​ ​impacts​ ​assessment

Conclusions A​ ​step-by-step​ ​process​ ​to​ ​achieve​ ​an​ ​overall​ ​conceptual​ ​design​ ​of​ ​The​ ​Reynoso​ ​Reservoir​ ​and it’s​ ​connecting​ ​water​ ​supply​ ​systems​ ​was​ ​taken​ ​throughout​ ​this​ ​assignment.​ ​The​ ​Reynoso Reservoir​ ​aims​ ​to​ ​supply​ ​Martinville​ ​and​ ​the​ ​surrounding​ ​dairy​ ​farms​ ​with​ ​a​ ​reliable​ ​water​ ​supply in​ ​the​ ​most​ ​cost-effective​ ​way.​ ​The​ ​engineering​ ​team​ ​also​ ​takes​ ​negative​ ​environmental​ ​impacts into​ ​account,​ ​and​ ​mitigation​ ​measures​ ​should​ ​be​ ​pursued​ ​throughout​ ​construction​ ​and post-construction.​ ​All​ ​Australian​ ​Standards​ ​and​ ​design​ ​brief​ ​requirements​ ​were​ ​successfully followed​ ​for​ ​the​ ​final​ ​designs​ ​that​ ​are​ ​proposed​ ​in​ ​the​ ​report,​ ​and​ ​it’s​ ​recommended​ ​that conceptual​ ​designs​ ​are​ ​not​ ​modified​ ​without​ ​professional​ ​engineering​ ​consultation.

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References

Bushmans​ ​Industrial​ ​(2016).​ ​Tank​ ​Material​ ​Comparison.​ ​Bushmans​ ​Industrial.​ ​Available​ ​at: http://bushmansindustrialtanks.com.au/information/tank-material-comparison​.

Haws,​ ​E.​ ​(1985)​.​ ​Dams​ ​and​ ​the​ ​environment.​ ​Paris,​ ​France:​ ​International​ ​Commission​ ​on​ ​Large Dams.

IndustrySearch​ ​(2017).​ ​Small​ ​Diameter​ ​Borehole​ ​Water​ ​Level​ ​Datalogger.​ ​IndustrySearch.

Available​ ​at: https://www.industrysearch.com.au/small-diameter-borehole-water-level-datalogger/p/33449​.

Manatunge,​ ​J.,​ ​Priyadarshana,​ ​T.​ ​and​ ​Nakayama,​ ​M.​ ​(2017).​ ​Environmental​ ​and​ ​Social​ ​Impacts​ ​of Reservoirs:​ ​Issues​ ​and​ ​Mitigation​.​ ​Oceans​ ​and​ ​Aquatic​ ​Ecosystems,​ ​1.

Standards​ ​Australia​ ​2006.​ ​Polyethylene​ ​Storage​ ​Tanks​ ​for​ ​Water​ ​&​ ​Chemicals​ ​(AS/NZS 4766:2006).​ ​Standards​ ​Australia​ ​International​ ​Ltd.​ ​Sydney,​ ​NSW. State​ ​of​ ​Michigan​ ​(2003).​ ​Tanks​ ​Section​ ​UIP​ ​11.​ ​Michigan,​ ​U.S.A.:​ ​State​ ​of​ ​Michigan,​ ​pp.1-8.

Team​ ​Poly.​ ​(2017).​ ​Water​ ​Tanks​ ​Compared:​ ​Poly​ ​Tanks​ ​versus​ ​Galvanised​ ​Steel​ ​Tanks.​ ​Available at: http://www.teampoly.com.au/knowledge-base/water-tanks-compared-poly-tanks-versus-galvanis ed-steel-tanks/​.

Tortajada,​ ​C.,​ ​Altinbilek,​ ​D.​ ​and​ ​Biswas,​ ​A.​ ​(2014).​​ ​Impacts​ ​of​ ​Large​ ​Dams:​ ​A​ ​Global​ ​Assessment.

Berlin:​ ​Springer​ ​Berlin.

Valdiya,​ ​K.​ ​(2015).​​ ​Environmental​ ​geology.​ ​New​ ​York,​ ​N.Y.:​ ​McGraw-Hill​ ​Education​ ​LLC.

Wang,​ ​Q.,​ ​Du,​ ​Y.,​ ​Su,​ ​Y.​ ​and​ ​Chen,​ ​K.​ ​(2011).​ ​Environmental​ ​Impact​ ​Post-Assessment​ ​of​ ​Dam​ ​and Reservoir​ ​Projects:​ ​A​ ​Review.​ ​In:​ ​The​ ​18th​ ​Biennial​ ​Conference​ ​of​ ​International​ ​Society​ ​for Ecological​ ​Modelling.​ ​Beijing,​ ​China:​ ​School​ ​of​ ​Environment,​ ​Beijing​ ​Normal​ ​University,​ ​p.1441.

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Appendices

APPENDIX​ ​A:​ ​Water​ ​Supply​ ​System​ ​for​ ​Township​ ​and​ ​Farms

Figure​ ​A.1:​ ​Water​ ​consumption​ ​calculations

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Figure​ ​A.2:​ ​Water​ ​consumption​ ​for​ ​farms

APPENDIX​ ​B:​ ​Town​ ​Water​ ​Supply​ ​System

Figure​ ​B.1:​ ​Calculations​ ​for​ ​101mm​ ​diameter​ ​piping

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Figure​ ​B.2:​ ​Calculations​ ​for​ ​83mm​ ​diameter​ ​piping

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Figure​ ​B.3:​ ​Calculations​ ​for​ ​115mm​ ​diameter​ ​piping

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Figure​ ​B.4:​ ​Calculations​ ​for​ ​129mm​ ​diameter​ ​piping

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APPENDIX​ ​C:​ ​Water​ ​Supply​ ​System​ ​for​ ​Farms

Figure​ ​C.1:​ ​Calculations​ ​for​ ​cross-sections​ ​of​ ​open​ ​channel​ ​flow

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APPENDIX​ ​D:​ ​Stability​ ​of​ ​Existing​ ​Slopes

Figure​ ​D.1:​ ​Geometry​ ​of​ ​existing​ ​slopes

Figure​ ​D.2:​ ​Stability​ ​analysis​ ​of​ ​left​ ​slope​ ​before​ ​construction

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Figure​ ​D.3:​ ​Stability​ ​analysis​ ​of​ ​right​ ​slope​ ​before​ ​construction

Figure​ ​D.4:​ ​Stability​ ​analysis​ ​of​ ​left​ ​slope​ ​after​ ​construction

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Figure​ ​D.5:​ ​Stability​ ​analysis​ ​of​ ​right​ ​slope​ ​after​ ​construction

Figure​ ​D.6:​ ​Excavation​ ​modification​ ​of​ ​left​ ​slope

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Figure​ ​D.7:​ ​Critical​ ​slip​ ​surface​ ​for​ ​excavation​ ​and​ ​fill​ ​modification​ ​of​ ​left​ ​slope

Figure​ ​D.8:​ ​Imported​ ​fill​ ​modification​ ​of​ ​left​ ​slope

Figure​ ​D.9:​ ​Critical​ ​slip​ ​surface​ ​for​ ​imported​ ​fill​ ​modification​ ​of​ ​left​ ​slope 30

Figure​ ​D.10:​ ​Excavation​ ​modification​ ​of​ ​right​ ​slope

Figure​ ​D.11:​ ​Critical​ ​slip​ ​surface​ ​for​ ​excavation​ ​modification​ ​of​ ​right​ ​slope

Figure​ ​D.12:​ ​Critical​ ​slip​ ​surface​ ​for​ ​excavation​ ​and​ ​fill​ ​modification​ ​of​ ​right​ ​slope

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Figure​ ​D.13:​ ​Imported​ ​fill​ ​modification​ ​of​ ​right​ ​slope

Figure​ ​D.14:​ ​Critical​ ​slip​ ​surface​ ​for​ ​imported​ ​fill​ ​modification​ ​of​ ​right​ ​slope

APPENDIX​ ​E:​ ​Embankment​ ​Dam

Figure​ ​E.1:​ ​Original​ ​geometry​ ​of​ ​embankment​ ​dam 32

Figure​ ​E.2:​ ​Embankment​ ​dam​ ​geometry​ ​with​ ​drainage

Figure​ ​E.3:​ ​Required​​ ​low​ ​hydraulic​ ​conductivity​ ​core​ ​modifications​ ​with​ ​no​ ​drainage

Figure​ ​E.4:​ ​Required​​ ​medium​ ​hydraulic​ ​conductivity​ ​core​ ​modifications​ ​with​ ​no​ ​drainage 33

APPENDIX​ ​F:​ ​Design​ ​Brief

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APPENDIX​ ​G:​ ​Single​ ​Store​ ​Flux​ ​Equations

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