Appendix A - Amphitheatre · 2019-11-22 · Amphitheatre is located between Avoca and Ararat along...

Appendix A - Amphitheatre

1.0 Amphitheatre Drought Response Plan 2

1.1 Sequential Plan of Action 2

1.2 Drought Response Triggers 4

2.0 Amphitheatre Water Supply System 5

2.1 System Description 5

3.0 Critical Community Assets 6

4.0 Bulk Entitlements, Groundwater Licences and other legal aspects 7

4.1 Bulk Entitlements 7

4.2 Groundwater Licence 7

5.0 Drought Experience, Operational Characteristics, Limitations and

Constraints 8

5.1 Hydrology and Hydrogeology 8

5.2 Drought Experience 8

5.3 Water Quality 8

6.0 Demand Analysis and Development of Water Restriction triggers 10

6.1 Water restrictions 10

7.0 Supply Side Actions 12

7.1 Amphitheatre Bore 12

7.2 Water Carting 12

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Central Highlands Water

Document title: Appendix A Amphitheatre 2017

Version no: 1

Author: P Russell

Doc code :BI/17/109569 Page 1 of 13

Produced by Central Highlands Water, November 2017.

Quality statement

Prepared by Strategic Water Resources Engineer

15/11/2017

Approved by General Manager Infrastructure Planning and Operations

15/11/2017

Disclaimer: This document has been produced to meet Central Highlands Water’s requirements for a Drought Preparedness Plan. Every effort has been made to ensure that the information contained herein was accurate at the time of production. Central Highlands Water makes no guarantee that the publication is without flaw of any kind and disclaims any liability for any error, loss or other consequence which may arise from use of this document for use other than as intended. Revision schedule

draft May 2017

Version 1 15 November 2017



Version no: 1

Author: P Russell


1.0 Amphitheatre Drought Response Plan This Drought Response Plan meets the requirements of the Statement of Obligations (2015) and CHW’s Water Restriction By-Law 405. 1.1 Sequential Plan of Action

Sequence Trigger Response

Action 1 At all times Maintain monitoring program.

Produce weekly water resource monitoring updates, monthly updates

for CHW Board.

Maintain operational capability to use the Amphitheatre bore.

Prepare annual Water Outlooks by November for publication on CHW

website.

Action 2 Reservoir level

below

groundwater

pumping trigger

Commence operation of groundwater bore.

Note: Groundwater is blended with surface supply in the bore tank

system. Check blend ratio for water quality acceptability by customers.

Review the distribution flushing and scouring program.

Action 3 Reservoir level

falls below the

stage 1 trigger

Review system outlooks and develop an approach to implement

restrictions. Given the nature of the Amphitheatre system it is unlikely

that all stages would be used. Similarly the timing of implementation (if

required) would most likely be at the start of summer when prospect of

further inflow reduces.

Continue groundwater operation.

Initiate community communications.

Action 4 Storage level

falls below

higher level

restriction

triggers (2,)

Review system water monitoring to understand the overall water

balance of the system.

Escalate community communications.

Increase monitoring of distribution system and make extra resources

available for leak detection and repair.

Consider reducing distribution system pressures.

Review distribution system flushing and scouring programs to minimise

water usage.

Increase monitoring of groundwater bore.

Implement stage 2, 3 water restrictions.

Make initial plans for water carting.

Action 5 Groundwater

monitoring

indicates that

Review system outlook taking account of reduced groundwater supply.

Consider remedial actions at bore, if any options are available.



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Author: P Russell


water levels

may drawdown

to pump intake

level in outlook

period.

Action 6 Projections

indicate that

reservoir

supplies may

be exhausted,

Water quality

issue in

Reservoir

makes source

un-useable

Initiate water carting with maximum groundwater use.

Implement stage 4 restrictions.

Commence water carting or other emergency water supply measures.

Fast track construction of new water supply option.

Reduce distribution pressures to lowest possible.

Continue community communications.

Cease mains flushing and scouring.

Action 7 Groundwater

levels recover

to normal

levels, reservoir

recovers.

Ease water restrictions.

Revert operating to normal arrangements.



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Author: P Russell


1.2 Drought Response Triggers



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Author: P Russell


2.0 Amphitheatre Water Supply System

2.1 System Description

Amphitheatre is located between Avoca and Ararat along the Pyrenees Highway in the Shire of Pyrenees. The Amphitheatre water supply system provides non-potable water to 76 connections and serves a permanent population of approximately 125 people. The water supply system consists of Amphitheatre reservoir with a capacity of 67 ML, located on Forest Creek, approximately 2km north west of the township. The reservoir receives water from springs within the catchment as well as surface runoff. The water supply has been a reliable resource and water restrictions have rarely been required before the Millennium Drought. The average annual bulk water demand at Amphitheatre is 13 ML. Amphitheatre water supply system is primarily supplied from the Amphitheatre Reservoir, however in periods of low storage levels, a drought relief bore can be utilised, which has a licence volume of 20 ML/year. In the past this bore water has been mixed with reservoir water, using the three 22kL inline storage tanks as mixing tanks, before being pressure injected into the system through a 3 L/s pressure pump. The quality of the reservoir water can be variable and tends to be highly coloured. High levels of turbidity and E. coli counts are also seasonal concerns. Community members tend to use private rainwater tanks to supplement the domestic supply. Figure 1.is a schematic diagram of the Amphitheatre water supply system.

Figure 1 Amphitheatre Water Supply System



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Author: P Russell


3.0 Critical Community Assets

As part of the consultation carried out for the 2017 UWS and the review of this plan, CHW

consulted with the community and council as part of its “Let’s Talk Water” campaign

regarding which community assets at Amphitheatre might require special consideration and

management in the event of severe drought conditions. The responses received are

summarised below.

1. Community Feedback

Place

Park Oval CFA Fire Refuge Total

Number of

responses

11 3 2 1 17

% of total

responses

65% 18% 12% 6% 100%

2. Council Feedback No Feedback from Council for Amphitheatre

Overall this feedback provides a useful reference in the event of drought conditions requiring the implementation of water restrictions. In the event of such circumstances CHW’s general approach would be:

Reconfirm with relevant groups at the time that these assets remain relevant of special consideration

Note that such assets as the Fire refuge require considerably more than just a ready supply of water. CHW will continue to liaise with relevant authorities with respect to this issue.

Use the Water Restriction By Law No.405 and the Exemption Principals and Guidelines for Permanent Water Saving Rules and Water restrictions (August 2012) as the basis for providing water for the identified (and other) assets.

It is expected that Integrated Water Management projects will provide alternative sources of water for many such assets as they are implemented across the CHW region. In some cases such alternative sources may be 100% reliable through droughts. Integrated Water Management concepts are still being developed and more work, particularly in terms of application to small rural communities such as Amphitheatre is required. CHW will keep the restriction process in place as a safety net for worst case scenarios.



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4.0 Bulk Entitlements, Groundwater Licences and other legal aspects

4.1 Bulk Entitlements

CHW holds a Bulk Entitlement for the Amphitheatre system, Bulk Entitlement (Amphitheatre) Conversion Order 2003, which was made under sections 43 and 47 of the Water Act 1989. Pertinent details are:

Maximum annual extraction 25 ML

Maximum extraction rate 1.5 ML/d

The reservoir volume 67 ML

No passing flow required

4.2 Groundwater Licence

CHW holds a groundwater licence for the Amphitheatre bore (#8003903). The licence was

issued by Grampians Wimmera Mallee Water under section 51, 67 and 145 of the Water Act

1989 with the following conditions:

Annual extraction limit 20 ML

Daily extraction limit 0.5 ML



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Author: P Russell


5.0 Drought Experience, Operational Characteristics, Limitations and Constraints

5.1 Hydrology and Hydrogeology

The Amphitheatre Reservoir is located on a tributary of the Avoca River. The reservoir capacity is 67 ML compared to an AAD of some 13 ML. However the system experiences high loses with a typical summer autumn drawdown of at least 30 ML of which only at most 1/3rd is attributed to actual consumption. Monitoring of this small system is confined to reservoir levels, rainfall and bulk flows. No stream gauging of inflows is made and water balance at the reservoir is complicated by the spring flow. Hence calculation of inflow by water balance is inaccurate. Detailed simulation model of the system has not been carried out. During wetter seasons, winter spring inflows, together with springs, will quickly fill the reservoir. However inflows sometimes fail and hence supplementary supply from other sources is required. The drought relief bore is constructed into shallow alluvial deposits along the Amphitheatre Creek to provide a supplementary supply during dry seasons. The licence has recently been renewed with information gained by pumping supporting the renewal. Despite this, careful monitoring of groundwater levels should be made if the bore is to be operated for extended periods during dry conditions. The water quality of the bore is unsuitable for direct supply to town and hence an arrangement of tanks and pressure pump has been set up to blend groundwater and surface water at a suitable ratio. Given that it is preferable to avoid using the bore as a stand alone supply, it is necessary to anticipate when water shortfall may occur and commence groundwater pumping early. 5.2 Drought Experience

It was during the Millennium Drought that it became evident that the Amphitheatre Reservoir is vulnerable to shortfalls if winter/ spring inflows fail. In 2002, 2006 and 2008 the reservoir failed to fill before summer and subsequently drew down to low levels by the end of the following summer/autumn period. On each of these occasions high level water restrictions were implemented (stage 2 in 2002, stage 4 in 2007 and stage 3 in 2009). While the systems subsequently recovered it was clear that some form of alternative supply was needed to provide supplement in the event of ongoing dry conditions. For example had the three drier years in this sequence occurred concurrently, then the system would have failed during the second year. The drought relief bore was developed during this time and commissioned in 2008. More recently the system again failed to fill and depleted to low levels in 2015 16. Restrictions were not implemented but instead water carting was carried out in the late summer period and blende with groundwater. 5.3 Water Quality

The Amphitheatre system is a regulated supply and is not for human consumption.



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Author: P Russell


Notwithstanding, water quality can have important impacts on this system. The raw water quality means that frequent flushing of the system is required. This has been addressed to some extent by normally passing the supply through the tanks and filters at the groundwater site. Heavy flushing can deplete reducing resources in dry years. At times the water quality can deteriorate to the extent that numerous customer complaints are made. In recent times this has been caused by storm events flushing high turbidity water into the reservoir, seasonal overturn of the reservoir (which is not aerated), failure of the floating outlet and failure of the outlet screen. Although not specifically drought related, the short term failure of the normal supply may require alternative supply to be implemented at short notice.



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Author: P Russell


6.0 Demand Analysis and Development of Water Restriction triggers

6.1 Water restrictions

Water restrictions have been used in Amphitheatre system in the past. However there are a number of factors which may make restrictions less effective at Amphitheatre than other systems: As a regulated supply in house use is very limited. Hence implementing high level restrictions may make the resource of no use to the community. The high losses on the system outweigh the consumption hence the system will deplete even with high level restrictions. The current best understanding of the split up of demand to its various components is shown in the table below.

Based on recorded bulk demand over the past 6 years Table 1 and Figure 2 below show the expected reduction and total demands at the 4 levels of restriction.

Table 1 Estimated current system demand

Restriction Scenario Base Demand (ML/yr) Restrictable demand (ML/yr)

Total demand (ML/yr)

No Restrictions 3.5 ML 10.1 13.6 Stage 1 Restrictions 3.5 ML 8.7 12.2 Stage 2 Restrictions 3.5 ML 3.5 7 Stage 3 Restrictions 3.5 ML 1.5 5 Stage 4 Restrictions 3.5 ML 0 3.5

Note that the unrestricted demand over this period is marginally higher than the AAD in CHW’s 2017 UWS which gives a more conservative outcome in terms of drought response and reflects the variable nature of water consumption in this system.

Current supply and demand trends

Base water demand is approximately 25% of total demand Residential usage accounts for approximately 88% of total water demand Non-residential usage accounts for approximately 6% of total water demand Concessional usage accounts for approximately 6% of total water demand



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Figure 2 Amphitheatre Demand Analysis



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7.0 Supply Side Actions Supply side options involve the progressive use of the various sources which are not normally connected to the system. 7.1 Amphitheatre Bore

This source was use developed during the Millennium Drought but has had only limited use. The water quality is high in TDS and dissolved iron and manganese. The purpose of the three tanks at the bore site is to aerate the water, which allows iron and manganese to settle out, and mix the groundwater with the reservoir water to bring it to acceptable water quality (TDS and hardness). 7.2 Water Carting

The demand at Amphitheatre could be met by water carting. Under emergency conditions water can be carted the tanks at the groundwater site or alternatively to individual household rainwater tanks.

Appendix A - Amphitheatre · 2019-11-22 · Amphitheatre is located between Avoca and Ararat along...

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