filtration risk table

7/23/2019 Filtration Risk Table

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Masterton DWS Water Safety Plan

3 FiltrationEven

t

No Cause Risk

WithoutPreventative

Measures

Indicators Preventative

Measures inPlace

Controlled Residual

Risk

Additional Measures That Could

be put in Place

Resp

P a r t i c l e s n o t b e i n g 3.1 Media

deficiencies

-Depth/quality

High

li!ely "medium#

-Post-filterturbidity

-$isual inspectionof filter

-Post filterturbidity chec!s

-Depth and typeof media aresuitable tomaintain quality

%ater

yes Moderate

possible "Medium#

&one 'equired ()

(P*

P a r t i c l e s n o t b e i n g 3.+

,nappropriateflo% rate

Moderate

possible "medium#

-levatedturbidity

-$isual inspection

of filtered %ater

-voiding suddenflo% rate changeson dirty filter

-*peratorstrained inoperationalprocedures

yes Moderate

unli!ely "medium#

&one 'equired ()

(P*

3 Filtration

Event

No Cause Risk Without

PreventativeMeasures

Indicators PreventativeMeasures in

Place

Controlled ResidualRisk

Additional Measures That Could be put in Place

Resp

P a r t i c l e s n o t b e i n g

v e d

3.1 ,ncorrect filter

bac!%ash

High

li!ely "medium#

-levated

turbidity postfilter

-Parameters in

place to trigger bac!%ash

-ffective bac!%ashprocedure

-$isual inspectionof bac!%ash

yes Moderate

possible "Medium#

&one 'equired ()

(P*




, n e f f i c

i e n t b a c ! % a s h 3.+

&o bac! up airscourcompressor

Moderate

li!ely "minor#

-,ncreased bac!%ash time %ithout it

-Poorly %ashedfilter media

-,ncreasedturbidity

&one in place &o Moderate

li!ely "minor#

-dditional air scour compressor

-dditional po%er supply to run it

()

(P*

5 lud!e Mana!e"entEven

tNo Cause Risk

WithoutPreventative

Measures


Place



Resp

) l u d g e n o t d r y i n g .1 Particularly

%et. )ludgenot dryingenough forremoval

0o%

possible "insignificant#

-)ludge %etterthan normal attime of removal

-$isual inspectionfor ponding

- solids testingrior to removal

-(%o sludgeponds. *ne onlinethe other drying

-nsure plenty ofdrying time

yes 0o%

unli!ely "insignificant#

()

(P*

l u d g e u n a b l e t o b e .+

)ludge has a dry consentlimit %hichrestricts land

filling ability

0o%


-)ludge too %et tota!e to landfill

-nsure sludgemeets criteriathrough in housetesting beforeremoval

-High storagecapabilities

yes 0o%


&one 'equired ()

(P*


tNo Cause Risk

WithoutPreventative

Measures


Place



Resp




0 e a c h i n g

.3 2nlined pond Moderate

possible "medium#

-elevatedcontaminantlevels in ground

%ater monitoring

-ore monitoringfor early detection

-(rigger levels

no Moderate

possible "Medium#

0ine ponds ()

(P*

M i c r o b i o l o g i c a l

i v e r

.4

)upernatentpump notturned off so

bac!%ash tan! fully pumpedinto river

High

li!ely "medium#

-(an! empty

-$isual

-5omplaints

-Policy in place toensure personsresponsible staysand %atches %hilepump runs

Partially 0o%

unli!ely "minor#

utomation of pumping system

-(imer

-(urbidity meter on outlet

-0evel s%itch

-larm

()

(P*


tNo Cause Risk

WithoutPreventative

Measures


Place



Resp

5 h e m i c a l

i n a t i o n o f

.

)upernatentpump notturned off so

bac!%ash tan! fully pumpedinto river

High

li!ely "medium#

-levatedchemical analysischec!

-Pea! results aftersupernatantpumped to river

-*ptimised plantfor minimalchemical usage

-,ncoming %atersupply restrictedto a certainquality reducing

partially 0o%

unli!ely "minor#

utomation of pumping system

-(imer

-(urbidity meter on outlet

-0evel s%itch

-larm

()

(P*

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