Post on 15-Oct-2020
Bathing Water Symposium
11th November 2015
Bathing Water Modelling to Improve Investment Decision Making
Andy Mortali (Scottish Water)
Elaine Hamilton (SEPA)
Scottish Designated Bathing Waters 2015 Classifications
SR10 Bathing Water Study Locations 2015 Classifications for SR10 Study areas
Collaborative Study Approach
SR10 Bathing Water Studies
Study area:
SEPA OPS Team:
Lead officer:
Report Type:
Report title:
Report section Page No Comment SW response SEPA feedback Actions following meeting on 05/06/2013 SEPA feedback v4 07/10/2013 SW response
Table 2.2 10
As with SEPA's comments on Table 6.2 of the NEEDS report is it necessary to
include all these assets in the table when many of them have either no bacterial
concentration or repeated bacterial concentrations associated with them?
These assets have been included in Table 6.2 for completeness
and will be included in Table 4.2 of the Needs report. No repeat
bacterial counting has been undertaken. See Needs comments
for further details.
From discussion on 05/06/2013 SEPA understands
that the network in Kirkcaldy is very complex ie
there are assets with multiple weir settings. To
accurately represent these in the DAS model all
weirs have been included as links in the model.
These have all been listed in Table 6.2 to ensure
this detail is not lost. SEPA notes that Table 4.2 of
the Needs report will be updated to reflect all the
assets listed in Table 2.2 (Options report) and Table
6.2 (Needs report).
This needs to be checked against the revised Needs
report when this is received.
Table 4.2 and table 6.2 amended in
the Kirkcaldy Needs report v4
Table 2.2 10
As with SEPA's comments on Table 6.2 of the NEEDS report there are a number of
assets listed in Table 2.2 of the OPTIONS report that do not appear in Table 4.2 of the
NEEDS Report. Please ensure there is consistency between the two reports and
between the tables within each report.
Table 2.2 will be updated for completeness as per table 4.2 in the
Needs report. To be confirmed when the Final report is issued
Can you expand out the assets under the Kinghorn
section to include all the assets. We understand they
may have been removed as they have no bacteriological
contribution but feel these should be included for
completeness. Previous comment that this table, table
2.2, should be consistent with per table 4.2 in the Needs
report still stands.
Kinghorn assets expanded in table
2.2 to cover all assets. Please note
that they all have no bacteriological
contribution to the overall bathing
water assessment.
Table 2.2 10
SEPA notes that the SW Asset Total includes the repeated bacterial concentrations
noted against the same assets. This could mean that the bacterial concentration from
some assets is double or even triple counted. Is this correct?
This is correct representation of the model and does not include
double counting. For example the output from the sewer model at
Lauder Road has three separate screens that lead to the outfall
and these are modelled as separate discharge hydrographs
within the sewer model and for direct comparison within the
marine model have been modelled as three separate
hydrographs, albeit discharging at the same location.
From discussion on 05/06/2013 SEPA understands
that the network in Kirkcaldy is complex and there
are assets with multiple weir settings. To
accurately represent these in the DAS model all
weirs have been included as links in the model.
SEPA notes the assurance that double/triple
counting has not occurred. Query closed. No response required
4. Modelled Solutions 16 v4
SEPA feels that footnotes 2 and 3 are fundamental to the
description of the modelled solution. and would like to see
these removed as footnotes and included in the main text
Footnotes two and three transferred
to the main text in section 4.1 and
removed from the footnotes.
4.1 14
SEPA notes that the removal of the blockage at Lauder Road catchment is considered
as an option. If the blockage is removed then the asset would operate as it should. Was
a scenario run to consider the 'as should' operation of the assets? If yes, what was the
outcome of this scenario?
As part of the optioneering stage the blockage at Lauder Road
was assessed. Removing the blockage results in a reduction in
spills at Lauder Road by approximately 30%. However, the asset
is still significantly impacting on the Bathing water quality at the
95%ile
From discussion on 05/06/2013 SEPA understands
that the DAS was altered to the 'as should' operate,
including the removal of Lauder Road siltation issue
and other issues relating to the WwTWs. SEPA
understands that this has been accepted by the
external auditor. SEPA appreciates that even under
the 'as should' operate scenario Lauder Road is still
impacting significantly on bathing water quality , at
the higher percentiles. No response required
4.1 14
SEPA notes the explanation in Footnote 2 and appreciates that a flow survey during the
bathing water season is required to confirm the base flow assumptions used in this
assessment. However, if the base flow is reduced (as detailed in Bullet Point 6) has the
bacterial concentration applied in the model been increased? It is SEPA's
understanding that the bacterial concentration for secondary treated effluent, as used in
the Needs assessment, was adjusted to take account of the dilution afforded by the
level of infiltration in the network. If this dilution is reduced by 50% but the bacterial
sources remain the same then should the bacterial concentration applied to the treated
effluent be revised upwards again? SEPA would like to discuss this further.
As part of the Needs assessment the full infiltration was included
within the modelling and this resulted in the reduction in
secondary WwTW values, however in the Option assessment
infiltration was reduced by 50% at the upper percentiles to
understand the impact that excessive infiltration would have on
the marine options. No increase in the bacterial load was
included in this option run where infiltration was reduced by 50%.
It might be anticipated that bacterial concentrations would
increase as infiltration decreases, but production rates based on
the population in the catchment were also considered and did not
indicate this was necessary. Furthermore, this makes up a very
small percentage of the total (only 6 FC/EC cfu at the 90th
percentile). For an investigation of options to meet the thresholds
at the 90th percentile the infiltration value has been returned to
100%.
From discussion at the meeting on 05/06/2013
SEPA understands that the reduced bacterial
concentrations were applied to the continuous final
effluent discharge in the Needs assessment, not
the intermittent CSO discharges (including the
WwTW CSOs).This enabled a better model
calibration to be achieved at the low percentiles in
the distribution. The reduction in bacterial
concentrations does not affect the higher
percentiles as these are influenced more by the
intermittent discharges, for which the bacterial
concentrations have not been adjusted. SEPA also
understands that in the Options assessment the
reduced default bacterial concentration for the final
effluent was not increased when inflitration was
reduced by 50% as this was shown to have little
impact, increasing the the bacterial level from 6
cfu/100ml to 12 cfu/100ml for the final effluent.
SEPA also notes that in the consideration of the
90%ile options the reduced bacterial concentrations
for the final effluent have not been applied. Query
closed. No response required
Figure 4.1 16
Please note that in the legend the bathing water area is referred to as Kirkcaldy Harbour
not Kirkcaldy Seafield as it should. Figure to be amended for the final report To be confirmed when the Final report is issued SEPA note this has been updated. Query Closed No response required
Figure 4.1 18 v4
SEPA thinks that the wrong map has been included and
that the map that needs to be included here is the
location map 4.1 as per the Kinghorn (Harbour) Bathing
Water Options Assessment v4, this map details the
locations of the new and revised long sea outfall locations.
Figure 4.1 included in this report does not show the
locations of the new and revised long sea outfall. In
addition the title for Figure 4.1 also appears incorrect,
there is no reference of location F instead it refers to
location G being an the location of an extension to the
current long sea outfall.
Figure 4.1 updated with proposed
outfall locations.
Table 4.2 18
The term 'compliance' is used in the column headings but the rBWD uses a
classification status assessment rather than compliance. Please amend this table
accordingly. This will be amended for the final report To be confirmed when the Final report is issued SEPA note this has been updated. Query Closed No response required
4.2 18
The report notes that Table 4.2 and Table 4.3 are the model results for the worst point in
the bathing water but the title of Table 4.2 indicates it is the node nearest the SEPA
monitoring point. Which is correct?
Table 4.2 is the SEPA monitoring point and 4.3 is the worst point
within the bathing water. This will be corrected in the final report To be confirmed when the Final report is issued SEPA note this has been updated. Query Closed No response required
Figure 4.2 18
Solution 3 on the graph does not seem to reduce the bacterial load by the 25%
indicated in Appendix B. SEPA would find it useful to have Figure 4.2 explained in more
detail.
Appendix B looks at the WwTW OCC discharge channel only
and the 28% reduction is noted for this alone (as noted in the first
reduction in the figure 4.2). The two other columns represent the
reduction by moving flows down the LSO at Charlotte Street (F)
and the extension of the WwTW LSO to G. Asset diversion to
each LSO is noted above Figure 4.2. Arrows can be added to
Figure 4.2 to highlight increase and decrease from the noted
bullet points above Figure 4.2.
SEPA notes this explanation. The arrows are not
required. Query closed. No response required
Section 4.3 28 v4
SEPA have not received the report as referenced: Atkins
2013 5110061.64.CO.020 Kirkcaldy Impact Assessment
report V4 Sent
Section 4.4 32 v4
SEPA feels that footnotes 5 and 6 are fundamental to the
description of the solution. and would like to see these
removed as footnotes and included in the main text.
Footnote 5 and 6 removed and
placed into the main body of the
text in section 4.4.
Table 4.5 33 v4
Table 4.4 details information for locations F and G (as per
the title) but the memo issued in June 2013 presents this
for locations A and G. Should this not be consistent or
should tables for A and G and F and G be presented, if
the solution likely to be between And F ?
This was amended following the
Options meeting held on the
05/06/2013, where SEPA stated
that location F gave them more
confidence in the options
assessment. Additional work is
required to locate the most suitable
point between location A and F, but
for this report it is location F that
has been selected as agreed with
SEPA.
Figure 4.6 28
The two plots appear to be very similar - is this correct? If the impact from diffuse
sources increases at higher percentiles SEPA would expect the plot for Combined Total
Assets to illustrate a higher bacterial concentration further down the coast compared to
the plot for SW assets only.
These plots were incorrect and have been amended in the report.
The figures now show the increase in diffuse pollution down the
coast. To be confirmed when the Final report is issued
Can you confirm that this has been updated. The plots
still seem to be incredibly similar. SEPA would expect
the plot for Combined Total Assets to illustrate a higher
bacterial concentration further down the coast compared
to the plot for SW assets only.
This figure has been updated, the
figures appear very similar due to
the upper boundary of the scale
used. Discharges from the fluvial
system match the discharges
locations for a number of SW
assets and at this upper percentile
(97.5) it is not possible to
distinguish the SW and diffuse
sources along the shoreline.
References v4
SEPA have not received the following two reports as
referenced: Atkins 2013 5110061.64.CO.020 Kirkcaldy
Impact Assessment report V4 AND Atkins 2013
5110061.64.CO.022 Kinghorn Impact Assessment report
v3
Version 4 reports are now available
for review - now sent
Appendix A 34
The totals for SW assets and diffuse sources appear to be incorrect. For example, the
totals for EC at 97.5th should 961 (SW assets) and 2061 (Diffuse sources). These are
different to those detailed in the table. Can you please check that the totals in the table
are correct?
The sum will not match the totals due to the statistical method
used to calculate the total impact. This is noted and explained in
the report.
SEPA appreciate that the the Totals for Diffuse and
SW asset contributions will not match the sum of
the data in the table due to statistical method used.
Query closed. No response required
Appendix B 36
Paragraph 3 explains the reduction in bacterial load expected if the base flow in the
network is reduced (i.e. infiltration is reduced). However, Paragraph 4 indicates that the
reduction in base flow for the 90%ile and 94%ile is probably not required as the total
SW asset contribution at these percentiles is significantly lower than 500cfu/ml. The
remaining part of the Appendix goes on to explain how infiltration will first be confirmed
and then reduced. However, if base flows are reduced by 50% should the bacterial
concentration applied, as part of the model, to the continuous flow from the WwTW
works be increased as there is less dilution in the influent. The original default bacterial
concentration was reduced due to issues with the model calibration. This was linked to
the significant level of infiltration into the system. SEPA would like to discuss this issue
further.
See row 14. We would be happy to discuss this further and it
should be noted that for an investigation of options to meet the
thresholds at the 90th percentile the infiltration value has been
returned to 100%.
See SEPA feedback in Row 14. SEPA is satisfied
this query is now closed. No response required
5110061_064_RW_CO_021 - Kirkcaldy Bathing Water Options Appraisal v4.pdf
Kirkcaldy (Seafield) BW
Fife
Steve Archibald
Revised BWD Options Report - Kirkcaldy (Seafield) Bathing Water
Target Objective, Extent of Bathing Water and Spatially Varying Performance
Source of Bacteria – Scottish Water / Other Sources
Investment Decision Tree
Key Principles
• Where SW intervention alone can
deliver an improvement in BW
classification then investment is
progressed.
• Where SW impacts alone do not
cause a poor classification then
investment should not be progressed
• Where a combination of sources are
impacting bathing water quality and
interventions are required to deliver
an improvement in class (or to
improve specific areas of the BW)
then SW investment should be
delayed until there is more certainty
on when other improvements will be
delivered.
Bathing Water Investment Decision Tree
Yes
No
No No
Yes Yes
Yes
No
Continued review and monitoring
Scottish Water SEPA
Update of Bathing Water
Profile to reflect model
outputs
SW Bathing Water Modelling
Are there diffuse pollution /
non SW sources impacting BW
quality
SEPA to undertake monitoring
to determine changes
resulting from improvement
at non SW sources
Are event and flow monitors
and reporting facilities in
place to monitor operation of
SW assets?
SW to provide operational
report to SEPA and update to
river and marine modelling
tools from reporting system.
Investment to deliver
monitoring and reporting
systems for SW assets
SW to maintain, improve and
update river and marine
modelling tools with new
data to refresh study outputs
Is there certainty that SW
intervention can deliver an
improvement in classification
at the Monitoring location?
Does SW asset impact Water
Quality anywhere in the BW? No further action
Agree revised CAR
licenses with SEPA
and implement
changes
SEPA to undertake catchment
management activities to try
and reduce diffuse pollution
level
SEPA to maintain and update
electronic signs and other
sources of public information.
SW Investment Requirements SR10 Bathing Water Study Locations
Conclusions
• The approach we have utilised has allowed SW to clarify an uncertain
investment requirement
• The development of the investment decision tree has generated a
consistent approach to decision making using a robust methodology,
signed off by all key stakeholders
• The approach has allowed us to understand more of the impacts on
Bathing Waters expected to be Poor and, by considering performance
across the entire BW, has improved our understanding of risk that
further bathing waters fail to achieve sufficient status.
• The approach has allowed Scottish Water to be confident that
investment will result in positive customer outcomes. It also allows
SEPA to understand where the focus on other sources is required.
THANK YOU
Andy Mortali (andy.mortali@scottishwater.co.uk)
Elaine Hamilton (elaine.hamilton@sepa.org.uk)