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Water Use

Supporting Guidance (WAT-SG-85)

Application of Standards to ThermalDischarges

Version: v1.0

Released: Feb 2011

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2 of 10 Uncontrolled if printed v1.0 Feb 2011

Copyright and Legal Information

Copyright 2011 Scottish Environment Protection Agency (SEPA).

All rights reserved. No part of this document may be reproduced in any formor by any means, electronic or mechanical, including (but not limited to)photocopying, recording or using any information storage and retrievalsystems, without the express permission in writing of SEPA.

Disclaimer

Whilst every effort has been made to ensure the accuracy of this document,SEPA cannot accept and hereby expressly excludes all or any liability andgives no warranty, covenant or undertaking (whether express or implied) inrespect of the fitness for purpose of, or any error, omission or discrepancy in,this document and reliance on contents hereof is entirely at the users own

risk.

Registered Trademarks

All registered trademarks used in this document are used for referencepurpose only.

Other brand and product names maybe registered trademarks or trademarksof their respective holders.

Update Summary

Version Descriptionv1.0 First issue for Water Use reference using approved content from

the following documents:

[DRAFT SG Thermal Discharges WITMT Final]

Notes

References: Linked references to other documents have been disabled in this web version

of the document. See the References section for details of all referenced documents.

Printing the Document: This document is uncontrolled if printed and is only intended to be

viewed online.

If you do need to print the document, the best results are achieved using Booklet printing orelse double-sided, Duplex (2-on-1) A4 printing (both four pages per A4 sheet).

Always refer to the online document for accurate and up-to-date information.

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v1.0 Feb 2011 Uncontrolled if printed 3 of 10

Table of Contents

1. Key Points .......................................................................................................... 42. Environmental Standards for Temperature......................................................... 5

3. Application of Standards..................................................................................... 7

3.1 New Discharges ....................................................................................... 73.2 Existing Discharges.................................................................................. 7

4. Regulatory Process Existing Discharges ......................................................... 84.1 Initial Assessment .................................................................................... 84.2 Licence Review Following Assessment Failure........................................ 8

References ........................................................................................................... 10

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1. Key Points

This document provides guidance on the application of environmentalstandards in relation to both existing and new thermal discharges.

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2. Environmental Standards for Temperature

The main legislative driver for controlling the impacts of thermal dischargeshas been the Freshwater Fish Directive. This Directive will be revoked by the

Water Framework Directive in 2013. There are now WFD standards fortemperature which SEPA is now using in classification and will now use inregulating discharges. The temperature requirements are expressed in threeforms as explained below.

Absolute temperature requirement (see table 1)

For each class there is an absolute temperature standard applied as anannual 98%ile

Increase/decrease over/under ambient temperature (see Table 1)

A discharge should not increase the ambient temperature by more than 2Cin waters of high ecological status or 3C in waters of good ecological statusas a 98%ile at the edge of the mixing zone. These uplift values are to beused in regulation of discharges but are not used in classification.

Release of water to rivers from the cold depths of reservoirs may result inreduced downstream river temperatures and adverse effects on ecology. It isproposed that a maximum allowable temperature drop be applied that mirrorsthe maximum uplift values. A step of 3C should be used for all cases exceptfor waters of high ecological status. In this case a maximum allowable drop of

2C is proposed. Limits on the drop in temperature may also be needed forgasification plants at liquid gas terminals, where cold water may bedischarged.

Lower Limit for Spawning

A review of the spawning temperatures of UK species indicates thatgenerally, the existing standard in the Freshwater Fish Directive, a maximum10C during the spawning season, should protect spawning of cool waterspecies. No such limit should be applied to warm water species. This is notfor use in classification but used, where appropriate, to regulate the operation

of thermal discharges.

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Supporting Guidance (WAT-SG-85)


Table 1 Temperature Standards for Rivers

High Good Moderate Poor

River TemperatureType

Non- Cypr. Non- Cypr. Non- Cypr. Non- Cypr.

River temperature (C)as an annual 98%ilestandard

20 25 23 28 28 30 30 32

Increase / decrease intemperature (C) inrelation to the ambientriver temperature, as anannual 98%ile standard

2 2 3 3 - - - -

Note - these values should not be used for lakes, estuaries and coastal waters.Non- = Non-cyprinid, Cypr. = Cyprinid

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3. Application of Standards

All thermal discharges should be assessed immediately below the mixingzone.

3.1 New Discharges

Apply regulatory standards relevant to existing class of water body if High orGood Ecological Status to ensure no deterioration. For example for a non-cyprinid watercourse, ensure no breach of 20C or 23C as an annual98%ile, 2C or 3C as an annual 98%ile uplift from ambient temperature and10C maximum during the breeding season. If existing status is less thangood, apply discharge limits to meet good status.

If a water body is at High status and the High/Good boundary temperature

limit of 20C as a 98%ile would be breached by a proposed thermaldischarge, this would be contrary to the WFD no deterioration requirementand discharge limits would have to be imposed to prevent this. The samewould apply if the discharge would breach the 23C Good/Moderateboundary. Derogation tests in WAT-RM-34: Derogation Determination -Adverse Impacts on the Water Environmentcould be applied. If the receivingwater body is a water dependant Special Area of Conservation, followSEPAs Natural Heritage Handbookguidance regarding AppropriateAssessments.

3.2 Existing DischargesIf classification standards are met for High or Good Ecological Status, nofurther action is required unless there is evidence of an ecological impact. Ifthere is ecological damage as a result of the thermal discharge, usedischarge limits and licence conditions to meet regulatory standards i.e. nobreach of uplift standards and no breach of 10C during spawning and earlyemergence for salmon and trout. This is generally taken to be mid October tomid March but river systems vary and advice should be taken from the localFisheries Trust or District Salmon Fishery Board staff and SEPA FisheriesScientists.

If classification standards are not met for Good Ecological Status, can theoperator provide evidence of no ecological impact attributable to the thermaldischarge? SEPA Fisheries Scientists can provide guidance on the evidencerequired for consideration as proof of no ecological impact. If no ecologicalimpact, no further action.

If still breaching the classification standard and ecological impact proven,tighten discharge limits further or look at cumulative impacts and reviewupstream thermal inputs.

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4. Regulatory Process Existing Discharges

4.1 Initial Assessment

Where thermal discharges are monitored the monitoring must include thereceiving watercourse downstream of the mixing zone. Compliance withWFD temperature classification standard and no ecological impact shown bySEPA, no further action is required.

If planned sampling shows temperature standard breached, give the option tooperator to install continual monitoring (hourly, 7 days per week) to takeadvantage of the annual 98%ile standard for upper temperature limit andcarry out fish studies to show if there is no impact. If compliance with theannual 98%ile classification standard and no ecological impact, no furtheraction.

4.2 Licence Review Following Assessment Failure

Assuming continual monitoring installed upstream and downstream, assessperiods of non-compliance with the environmental standards. Discuss licencereview and likely variation to impose uplift standards on discharge withoperator. Three stage process, over 3 cycles of RBMP if necessary:

1. Work with operator, for a low cost solution, to make operationalchanges to reduce peak temperatures eg when stills are driving;

2. Work with operator to consider technical improvements regarding

capital investment to reduce peak temperatures eg heat recoverysystems, cooling ponds, cooling towers (where step i does not work);

3. Where operator unwilling to take measures i and ii request necessaryinformation from the operator to assess compliance with standardagainst derogation process as perWAT-RM-34: DerogationDetermination - Adverse Impacts on the Water Environmentand WAT-RM-41: SEPA Initiated Variations: Exemption Tests; this will be part ofthe SEPA initiated variation.

Note that failure to meet the WFD temperature standard is a failure of thewater body to meet Good Status; however WFD derogations may apply. Thetests are set out in WAT-RM-34 / WAT-RM-41 and are based on whethermeeting the standard is disproportionately expensive or technically feasible.In order for SEPA to properly assess this, the operator must also have shownthat all practicable steps are taken to mitigate the adverse impact on thestatus of the body of water. Therefore the operator must submit informationon the first 2 stages in their application to vary their licence.

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Regulatory Process Existing Discharges


Figure 1 Example process for an existing discharge to a good statuswatercourse

* Note: Ordinarily no further action is required unless additional information is available eg reportsfrom District Salmon Fishery Board or Fisheries Trust indicating fish data problems. These may becaused by breaches of 10C limit during spawning/emergence or spikes in discharge temperaturesnot picked up during routine sampling and further investigations will be necessary. This may takethe form of installation of continuous temperature monitoring.

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References

NOTE: Linked references to other documents have been disabled in this webversion of the document.

See the Water >Guidance pages of the SEPA website for Guidance and otherdocumentation (www.sepa.org.uk/water/water_regulation/guidance.aspx).

All references to external documents are listed on this page along with an indicative URL tohelp locate the document. The full path is not provided as SEPA can not guarantee its futurelocation.

Key Documents

WAT-RM-34: Derogation Determination - Adverse Impacts on the WaterEnvironment

WAT-RM-41: SEPA Initiated Variations: Exemption Tests

Natural Heritage Handbook(SEPA Intranet, ID=2242)

Freshwater Fish Directive 2006/44/EC(CELEX: 32006L0044)

- End of Document -