MWC Retarding Basin Inspection

• Retarding Basin Name

• Asset No

• Weather

• Location
  Address

• Depth of water in Basin

Flow in Outlet

• undefined

• Conducted on

  Date

• Prepared by

• • Plan Inspection – Choose RB’s in a similar area. (Refer to Inspection program)
  • Print previous inspection reports, GIS map of RB’s, review plans on inflow (if available)
  • Notify someone if you plan to work alone.
  • Review TRA, and ensure it is available during inspection.

• • Working alone at remote locations - lack of communication.
  • Slips trips and falls by walking on natural uneven ground
  • Cuts and abrasions from vegetation
  • Collision with animal or other vehicle.
  • Risk of drowning by falling in the basin or any other watercourse
  • Abuse from hostile visitors or community.
  • Fall from heights
  • Bites or stings (bees/wasps, snakes, mosquitos, spiders etc.

• • Completed Inspection checklist (attached)
  • Map of Retarding Basin showing the location of Actioned items.
  • Labelled photographs of Action items
  • Photographs of entire inspection.

• •Before you start work
  •After an extended break or
  •When circumstances change

• Are you doing high risk construction work?

  Yes

  No

  N/A

• Identify threats

  Select No threats - Good to Go 1 or 2 Threats - Proceed with Caution More than 3 Threats - Stop

  • No threats - Good to Go
  • 1 or 2 Threats - Proceed with Caution
  • More than 3 Threats - Stop

• 

Embankment - Upstream face of wall

• Potential issues - Erosion through the dam embankment leading to dam breach/ failure.
  Whirlpool or vortices would be associated with significant downstream leakage).

• Are there noticeable patches of fresh growth grass or patches that have died can indicate potential wet patches/seepage?

  Yes

  No

  N/A

• Is there an unusual increase in monitored seepage?

  Yes

  No

  N/A

• Is there new seepage, indicated by wet patches on the downstream slope of the embankment?

  Yes

  No

  N/A

• Are there any variation in colour /clarity in any seepage water due to soil particles (evidence of internal erosion/ piping)?

  Yes

  No

  N/A

• Photos of downstream embankment

  Media

• Any additional comments?

Embankment - Downstream face of wall

• Potential issues - Erosion through the dam embankment leading to dam breach/ failure.
  Whirlpool or vortices would be associated with significant downstream leakage).

• Are there noticeable patches of fresh growth grass or patches that have died can indicate potential wet patches/seepage?

  Select Yes No N/A

  • Yes
  • No
  • N/A

• Is there an unusual increase in monitored seepage?

  Yes

  No

  N/A

• Is there new seepage, indicated by wet patches on the downstream slope of the embankment?

  Yes

  No

  N/A

• Are there any variation in colour /clarity in any seepage water due to soil particles (evidence of internal erosion/ piping)?

  Yes

  No

  N/A

• Is there a whirlpool (vortices) in basin?

  Yes

  No

  N/A

• Photos of upstream embankment

  Media

• Any additional comments?

Embankment Piping (please note in comments if on upstream or downstream face)

• A flow path can be created along the outside of the pipe, or along dead tree roots.
  Pipping can lead to rapid erosion of the embankment.

• Is there any sign of a structurally damaged pipe, such as a collapse or fracture or joint failure? ?

  Yes

  No

  N/A

• Are there signs of erosion along the alignment of the outlet to the exit structure?

  Yes

  No

  N/A

• Any materials being transported by seepage flows at existing or new areas (such as discoloured seepage water or sediment deposits)?

  Yes

  No

  N/A

• Are there trees/shrubs growing on the embankment (which could lead to flow path through the embankment along the tree roots) (If yes are they dead or are they growing?).

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

Embankment Cracking (please note in comments if on upstream or downstream face)

• Shrinkage cracks allow water to enter the embankment and weaken it.
  Severe cracking can lead to seepage.

• Is there severe cracking with or without leakage on the embankment?

  Yes

  No

  N/A

• Is there shrinkage cracks that may result in an open pathway?

  Yes

  No

  N/A

• Any whirlpools visible in the dam?

  Media

• Photos

  Media

• Any further comments

• Add media

  Media

Embankment Movement (please note in comments if on upstream or downstream face)

• Structural/slope instability of the embankment or seepage path through embankment, which may lead to dam breach or failure.

• Is there signs of movement or excessive and/or differential settlements in the embankment?

  Yes

  No

  N/A

• Are there signs of embankment slides or slumps or evidence of slides occurring (longitudinal cracking)?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

Embankment Sinkhole (please note in comments if on upstream or downstream face)

• A sinkhole or void within or close to the embankment could cause localised caving, sloughing, and instability or reduced embankment cross-section.

• Is there a sinkhole within the basin at close vicinity of the embankment?

  Yes

  No

  N/A

• Are the any followups required with Dam owner/s? Please detail

• Photographs

  Media

• Any further comments

Embankment Erosion (please note in comments if on upstream or downstream face)

• Degradation of embankment, & sometimes reduction in crest levels, which will reduce factor of safety of embankment and may lead to failure.

• Is there any erosion along the embankment?

  Yes

  No

  N/A

• Are there erosion gullies developed on the surface of the embankment?

  Yes

  No

  N/A

• Is there surface depression, soft spots and boggy areas, which could lead to uncontrolled seepage through the embankment?

  Yes

  No

  N/A

• Is there excessive settlement in the embankment? <br><br>This could be due to wheel ruts from vehicles or improper grading following initial construction.

  Yes

  No

  N/A

• Are there defects in the erosion protection that could lead to localised erosion? Poor grass cover on embankment

  Yes

  No

  N/A

• Photos

  Media

• Any further questions

Embankment Other (please note in comments if on upstream or downstream face)

• Any damage that could lead to embankment failure.
  
  Pest and other animal activities can lead to embankment failure.

• Is there any other physical damage to the embankment?

  Yes

  No

  N/A

• Is there vermin / animal damage such as rabbits and fox’s; in the embankment may be the initiation of an erosion hole?

  Yes

  No

  N/A

• Photos

  Media

• Any further questions

Structural Defects in Outlet works

• Damaged outlet pipe leading to soil erosion around the embankment wall could lead to structural failure.
  Blockage can increase the possibility of the basin filling.

• Is there a break/damage in the outlet pipe?

  Yes

  No

  N/A

• Is there a sinkhole or subsidence around the outlet?

  Yes

  No

  N/A

• Is the outlet blocked? Or is there potential for blockage?

  Yes

  No

  N/A

• Is there a build-up of debris or silt before the outlet?

  Yes

  No

  N/A

• Is there vegetation growing around the outlet that could partially or fully block the outlet?

  Yes

  No

  N/A

• Are there handrails around the outlet that are damaged?

  Yes

  No

  N/A

• Is there missing or non-legible safety signs?

  Yes

  No

  N/A

• Are there concrete cracks or spalling?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

Structural Defects in Inlet works

• Is the inlet an underground pipe with headwall?

  Yes

  No

  N/A

• Is the inlet an open channel / waterway?

  Yes

  No

  N/A

• Is there vegetation growing around the inlet that could impact flows?

  Yes

  No

  N/A

• Are there handrails around the Inlet that are damaged?

  Yes

  No

  N/A

• Is there missing or non-legible safety signs?

  Yes

  No

  N/A

• Are there concrete cracks or spalling?

  Yes

  No

  N/A

• Photos

  Media

• Any further questions

Embankment Spillway

• Reduces the capacity of the spillway. Could lead to embankment overtopping.

• Is the spillway earthen material? If so comment on the grass coverage)

  Yes

  No

  N/A

• Is there more than one spillway?

  Yes

  No

  N/A

• Is there any erosion around the spillway?

  Yes

  No

  N/A

• Is there vegetation growing around the spillway?

  Yes

  No

  N/A

• Is there something blocking the spillway?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

High flow spillway / Gloryhole

• Is there any issues with the High Flow outlet?

  Yes

  No

  N/A

• Is there any concrete damage?

  Yes

  No

  N/A

• Are there any public safety concerns?

  Yes

  No

  N/A

• Are there any safety signs?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

• Is there a MWC advisory sign?

• Is there a MWC advisory sign?

  Yes

  No

  N/A

• Is there any other safety signs damaged?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

• Is the Retarding Basin open to the public?

  Yes

  No

  N/A

• Are there gates restricting vehicular access?

  Yes

  No

  N/A

• Are there missing MWC locks on gates?

  Yes

  No

  N/A

• Are there any holes within boundary fences that compromise security?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

• Safety should be considered for both maintenance workers and the public.

• Is there a fall from heights anywhere within the basin? E.g. Outlets, Inlets, pedestrian bridges etc..

  Yes

  No

  N/A

• Is there any other missing locks on grates?

  Yes

  No

  N/A

• Are there any slips trips and falls?

  Yes

  No

  N/A

• Is there any other inadequate handrails/grills and grates?

  Yes

  No

  N/A

• Photos

  Media

• Any further comments

• Increased possibility of water overtopping the embankment that could lead to structural failure.

• Is there dumped rubbish within the basin that can lead to a blockage of the outlet?

  Yes

  No

  N/A

• Is there offensive graffiti within the Retarding Basin?

  Yes

  No

  N/A

• Is there any vandalism that should be reported? (Intended damage)

  Yes

  No

  N/A

• Is there a build-up of silts, debris or vegetation along the watercourse/ drain within the Basin?

  Yes

  No

  N/A

• Are there any other concerns?

  Yes

  No

  N/A

• Photos

  Media

• Any other comments

• Reassess Item

• Have you read the previous report ?

  Yes

  No

  N/A

• Are there any additional Action Items from the previous report that requires a follow up?

  Yes

  No

  N/A

• Notes and comments and actions to be completed arising from the audit

• Are the any followups required ? Please detail

• Any sketches can be provided here

  Drawing

• Does a Service request needs to be raised for any maintenance Action Items identified ?

  Yes

  No

  N/A

• Please sign electronic signature here?

  Sign