FOREST PRACTICES BOARD - fpa.tas.gov.au · Web viewPublic ExposureThe risk to the public as a consequence of a retained tree (or limb) falling onto a public place, determined by

FPA Risk Assessment Form

FOREST PRACTICES AUTHORITY

RISK ASSESSMENT FORM

This form is for use in public places where:

1. Trees are being retained under a forest practices plan (FPP) for natural and cultural heritage values, or

2. Trees on land adjoining an FPP may be subject to a higher risk of wind throw due to the harvesting of trees under the FPP.

Throughout this form, trees in both these categories will be referred to as ‘trees which will remain after adjacent harvesting’.

Public places means any areas used by the public, such as roads, trails, buildings, picnic areas etc.

This form must be completed by a suitably trained person before an FPP may be certified in situations where the proposed harvesting or retention of trees would potentially result in an increased risk to the public. The Forest Practices Officer certifying the FPP must ensure that the provisions under the plan will, so far as is reasonably practicable, not cause an increased risk to the public.

This form does not cover the broader aspects of hazard identification and risk management associated with forestry operations. These matters fall under the Work Health and Safety Act 2012 and relevant provisions for forestry operations are detailed in the Forest Safety Code (Tasmania) 2007.

_________________________________________________

Date: ................................................................................................

FPP no: ................................................................................................

Coupe no: ................................................................................................

Location: ................................................................................................

Landowner: ................................................................................................

Road or place name: ................................................................................................

Person(s) carrying out assessment: ................................................................................................

................................................................................................

Signature(s): ................................................................................................

................................................................................................

Outcome of risk assessment:Risk score is (tick one option) Risk acceptable

Risk unacceptable

Page 1 of 17

Version 2.0 June 2015 Trim 2015/39019

Hardcopies of this document may not be up to date. Please refer to the FPA website for the latest version.


PROCEDURE FOR ASSESSING THE RISK TO PUBLIC SAFETY FROM TREES WHICH WILL REMAIN AFTER ADJACENT HARVESTING

1 Describe any individual hazardous trees requiring removal from the areas of trees which will remain after adjacent harvesting

The removal of individual hazardous trees may greatly reduce the risk to the public, providing adjoining retained trees are not damaged in the process.

Hazardous trees are trees that should be inspected and marked for removal as part of the normal safety risk assessment procedure for a forest operation.

Hazardous trees (definition from Forest Safety Code (Tasmania) 2007):

a. all trees with widow makers within one tree length of the landing;

b. trees containing or affected by any of the following: - excessive drainage problems as a result of snigging; - exposed root system; - root, trunk or stem damage; - exposure to vibration; or - potential for impact by machinery or snigged log.

c. trees with shallow root systems located in unstable ground conditions;

d. dead trees;

e. trees with root systems exposed to excessive drainage causing erosion or soft soil conditions;

f. trees regularly exposed to machinery vibration;

g. all trees with an obvious lean towards the landing;

h. trees exposed to prevailing wind. ‘Exposed’ means where an adjacent tree, upwind of prevailing wind direction, has been removed or the tree closest to the landing is 10% higher than surrounding trees and is located up-wind of the log landing. If the wind changes, trees in other orientations may come within this classification;

i. trees subject to excavation on the landing site within less than 5 trunk diameters and to a depth greater than 1 trunk diameter. From this point benching may only occur at 45 degrees. Should erosion occur, the tree is to be felled;

j. trees causing obstruction to snig tracks or landing access.

Page 2 of 17




When conducting the risk assessment procedure described in the following sections of this form, individual hazardous trees can be assumed to be still in place for ‘before harvesting’ assessments, and to have been removed for ‘after harvesting’ assessments.

Has a person with tree-felling experience been consulted? yes

no

Describe any hazardous trees in the area proposed for retention, attach sketch map, describe location, indicate how marked etc.

.

………………………………………………………………..........................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

.........................................................................................

Sketch Map

Page 3 of 17




2 Factors affecting the potential safety risk to the public from trees which will remain after adjacent harvesting

The factors to be considered are grouped into ‘Probability’ and ‘Public Exposure’ factors:

Probability Factors affecting the likelihood of retained trees falling onto a public place, potentially causing a public safety risk – called ‘Probability’ in the Risk Assessment Calculator at the back of this procedure.

Public Exposure The risk to the public as a consequence of a retained tree (or limb) falling onto a public place, determined by the level of public usage of a public place – called ‘Public Exposure’ in the Risk Assessment Calculator in section 5.

2.1 Calculation of ‘Probability’

Assessment of factors affecting the likelihood of trees falling onto a public place

Harvesting can reduce the likelihood of trees falling onto a public place by removing the trees. Alternatively, harvesting can increase the likelihood of trees falling onto a public place by increasing the exposure to wind for adjacent trees which remain.

A number of factors will affect the likelihood of trees falling onto a public place. These are:

1) slope and distance of the trees from the public place

2) drainage

3) stand characteristics

4) exposure to wind.

These factors are evaluated both (i) Before harvesting and (ii) After harvesting to determine the ‘Probability’ of trees falling onto a public place using a points score system (pages 5 to 9).

Page 4 of 17




2.1.1 Slope and distance of the area in which trees will remain after adjacent harvesting

Slope – Trees on the uphill side of the public place will obviously present a greater risk than trees on the downhill side. The steeper the slope, the greater the risk from trees on the uphill side, and the lesser the risk from risk-affected trees on the downhill side.

Distance – Trees greater than one tree length from the public place will present a very small risk unless they are on a steep bank above the public place. Trees immediately adjoining the public place will generally present the greatest risk of falling on the public place.

Scoring:

In the event of a tree or large limb falling, the chances of it falling onto the public place are:

0 Slight – e.g. Trees are next to the public place and downslope, or are at least half a tree length away from the public place on level ground (<12o approximately) or on the same contour

1 Moderate – e.g. Trees to be retained are closer than half a tree length from the public place on level ground or on the same contour, or trees are more than half a tree length from the public place but uphill on a moderate slope (12–20o approximately)

2 High – e.g. Trees are closer than half a tree length from the public place and moderately upslope (approximately 12-20 o) or trees are more than half a tree length from the public place but steeply upslope (20–26o approximately)

3 Very high – e.g. Trees are closer than half a tree length from the public place and steeply upslope (>26o approximately)

(i) Score before harvesting = ……..

(ii) Score after harvesting = ……..

Note: The score after harvesting will always be the same as or lower than the score before harvesting. A lower score after harvesting may result if any individual hazardous trees identified in Section 1 are within a tree length of the public place and are to be removed during harvesting.

Comments:

Page 5 of 17




2.1.2 Drainage of the area in which trees will remain after adjacent harvesting

This category includes consideration of the factors that affect the wind firmness of trees which will remain after adjacent harvesting. Poorly drained soils have low strength. This, combined with shallow tree rooting, results in a greater risk of windthrow. Seasonally saturated soils may be similar. There may be a history of windthrow in the area. Forestry activities can affect the potential for windthrow by directing water away or onto certain areas.

Scoring:

0 = Good drainage

1 = Moderate drainage

2 = Poor drainage

Score before harvesting = ……

Score after harvesting = ……

Note: As harvesting is unlikely to affect drainage significantly the score after harvesting will nearly always be the same as before harvesting.

Comments:

.

………………………………………………………………..........................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

.........................................................................................

Page 6 of 17




2.1.3 Stand characteristics of the trees which will remain after adjacent harvesting

The factors that need to be considered include the height of the stand, the size of the tree crowns, the species of trees, the soundness of individual trees (as per the section regarding evaluation of individual hazardous trees in Section 1), tree lean and stand age (regrowth, overmature etc.). In some cases the potential for large limbs blowing out of the tops of trees may constitute the greatest risk. If there is significant root damage to trees (e.g. caused by previous road construction) then consideration should be given to increasing the score.

Scoring:

0 = Low risk - e.g. small to medium sized regrowth or plantation

1 = Moderate risk – e.g. large regrowth or mature retained trees with small sound crowns

2 = High risk – e.g. overmature trees or mature trees with large crowns or significant lean toward the public place, or any pine trees or large hardwood plantation trees. Trees may have defective butts.

Score before harvesting = ……..

Score after harvesting = ……..

Note: The score after harvesting may be lower than that before harvesting where removal of individual hazardous retained trees is planned (as per section 1).

Stand description:

.

………………………………………………………………..........................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

........................................................................................

Page 7 of 17




2.1.4 Exposure to wind in areas in which trees will remain after adjacent harvesting

The relative risk exposure of the site should be judged considering factors such as position on slope, aspect, and exposure to prevailing strong winds, especially during winter/spring when soils may be saturated.

The wind exposure of trees adjoining a public place may be increased due to the proposed harvesting. The increase in exposure will relate to the harvesting system used (clearfall, heavy or light partial harvesting, thinning), and the width and dimensions of any strips or clumps of trees which will remain after adjacent harvesting. The main risk associated with harvesting will be a greater potential for windthrow in the first year after harvesting.

Scoring:

(i) Before harvesting

0 Sheltered – the trees adjoining the public place are relatively sheltered from wind

1 Exposed – the trees adjoining the public place are relatively exposed to wind due to position on slope, aspect etc. or due to the presence of a large opening facing the strongest wind direction adjoining the public place

(i) Score before harvesting = …….. (must be 0 or 1)

(ii) After harvesting

Add 0 to the ‘Before harvesting’ score if harvesting will not affect the exposure to wind of trees adjoining the public place, e.g. where a wide retention strip is retained between the harvested area and the public place

Add 1 to the ‘Before harvesting’ score if harvesting will cause some increase in the exposure to wind of trees adjoining the public place, e.g. where a narrower retention strip is retained between the harvested area and the public place, or where light partial harvesting is undertaken with no retention strip.

Add 2 to the ‘Before harvesting’ score if harvesting will cause a significant increase in exposure to wind of trees adjoining the public place, e.g. where a narrow retention strip is retained between the harvested area and the public place, or where heavy partial harvesting is undertaken with no retention strip.

(ii) Score after harvesting = …….. (must be from 0 to 3)

Comments:

.

………………………………………………………………..........................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

..................................................

Page 8 of 17




Calculation of ‘Probability’ of trees or limbs falling onto a public place following harvestingIn this section the chance of retained trees or large limbs falling onto a public place both before and after harvesting is calculated.

(i) Before harvesting

Score for: 1) Slope and distance (from page 5) …………

2) Drainage (from page 6) …………

3) Stand characteristics (from page 7) …………

4) Exposure to wind (from page 8) …………

Sum of 1) to 4) above = PROBABILITY SCORE before harvesting …………

(ii) After harvesting

Score for: 1) Slope and distance (from page 5) …………

2) Drainage (from page 6) …………

3) Stand characteristics (from page 7) …………

4) Exposure to wind (from page 8) …………

Sum of 1) to 4) above = PROBABILITY SCORE after harvesting …………

Use the Probability Scores calculated above in the table below as a guide to assess the ‘Probability of Occurrence’ of trees or large limbs falling onto the public place and constituting a risk to public safety both (i) before harvesting and (ii) after harvesting.

TABLE 1

Probability Score

Probability of Occurrence

Description

10 Almost certain The event is expected to occur in most circumstances

8 - 9 Very likely The event will probably occur in most circumstances

6 - 7 Unusual but possible

The event should occur at some time

4 - 5 Remotely possible The event could occur at some time

0 - 3 Very unlikely The event may occur only in exceptional circumstances

Probability of Occurrence: (i) Before harvesting ………………………………………………….

i. After harvesting…………………………………………………….

Page 9 of 17




2.2 Calculation of ‘Public Exposure’The level of usage of a public place, (‘Public Exposure’ on the Risk Assessment Calculator located at the end of this document), will determine the chance of injury to the public should a tree or limb fall onto the public place. The main risk will be associated with a vehicle colliding with a fallen tree, or of a tree falling on a building, camping area etc. whilst occupied. A much lesser risk will be that of a tree falling directly onto a vehicle.

For roads make an estimate of the average number of vehicles per day (including those associated with forest operations) on a year round basis, or if the period of risk is considered very seasonal, for that period of the year.

In some circumstances the public exposure rating after harvesting may different to that before harvesting, e.g. it may be decided that to further reduce the public risk the road will be closed during periods of high winds in the first year after harvesting; or it may be decided to send out a patrol early each morning where there has been strong winds to remove any debris which has fallen on the road.

For other public places (buildings, camping areas etc.), make your own determination on whether usage is continuous (e.g. occupied buildings), frequent, occasional, infrequent or rare.

Use the following tables as a guide to calculate the ‘Public Exposure’ rating before harvesting and after harvesting (usually the same):

TABLE 2A - ROADS

Estimated no. of vehicles per day

Typical Road Type Public Exposure Rating (refer Risk Assessment Calculator)

>100 Mostly sealed roads – highway, major tourist road, link road etc.

Frequent

25–100 Main country road, major logging road Occasional10–25 Mostly unsealed roads – minor country

road, major logging roadInfrequent

<10 Minor logging road Rare

TABLE 2B – OTHER PUBLIC PLACES

Type of Public Place Public Exposure Rating (refer Risk Assessment Calculator)

Occupied building ContinuousHigh usage camping or picnic area FrequentLow usage camping or picnic area, walking track etc.

Rare to Occasional

Public Exposure Rating: (i) Before harvesting………………………………………………………

(ii) After harvesting …………………………………………………………………

Page 10 of 17




3 Possible consequences ‘Possible Consequences’ on the Risk Assessment Calculator will be based on a judgment of the most likely degree of injury should an accident occur due to a tree or limb falling (or having fallen) on a public place.

Roads

Consider factors such as:

Typical speed of vehicles (affects the ability to stop, and the speed of impact in a collision).

Sight distance (when a fallen tree first becomes visible from a vehicle).

Normal stopping distance (for a vehicle travelling at 60 km/hr is about 45 m on a dry bitumen road, or at least 60 m on a wet bitumen road or gravel road).

Types and numbers of vehicles using the road (e.g. the road may frequently be used by tour buses).

Likely time taken to clear the hazard from the road

Size of the retained trees or limbs that are likely to fall on the road.

As a guide it can be assumed that if a vehicle collides with a large tree and the speed at impact is 60 km or over, then fatalities are likely. On a gravel road the speed of impact would normally be below 60 km/hr, so fatalities are unlikely.

For an occupied building, camping area etc. you will have to take into account the number of occupants/users and frequency of occupation/use.

Buildings, camping areas, walking tracks etc.

The main risk will be from a tree or large limb falling directly onto a building or onto people. The consequences are likely to be serious injuries or fatalities.

Before and after harvesting

The possible consequences are unlikely to change following harvesting. However, there are circumstances where they may change e.g. improved sight distance along a road due to harvesting may reduce the possible consequences.

What is the most likely Possible Consequence? (of those listed on the Risk Assessment Calculator):

Before harvesting:……………………………………………………………………………………………………….

After harvesting:………………………………………………………………………………………………………….

Comments:

.

………………………………………………………………..........................................................................................

Page 11 of 17




...........................................................................................................................................................

.........................................................................................................................................................

Page 12 of 17




4 Using the Risk Assessment Calculator in section 5

The notes below indicate how to use the Risk Assessment Calculator graph. For each factor below you will need to plot on the graph the risk:

Before harvesting – use a dashed line ----------------

Consider the factors below and draw a dashed line on the Risk Assessment Calculator.

Probability

Mark the point on the ‘Probability’ line on the Risk Assessment Calculator as determined in Table 1 (page 9). The point can be plotted based on the Probability Score (0 to 10) or the Probability of Occurrence category, whichever is considered most appropriate.

Public Exposure

Mark the point on the ‘Public Exposure’ line on the Risk Assessment Calculator as determined in Table 2A or 2B (page 9).

Possible Consequences

Mark the point on the ‘Possible Consequences’ line on the Risk Assessment Calculator as determined under section 3 (page 10).

Risk Score

The Risk Score is calculated as follows:

Draw a straight line on the Risk Assessment Calculator from the calculated Probability through the calculated Public Exposure to the Tie Line.

Draw a straight line on the Risk Assessment Calculator from the point on the Tie Line through the calculated Possible Consequences to intersect the Risk Score line.

The point where you have intersected the Risk Score line is the Risk Score. Write the Calculated Risk Score in the ‘Before Harvesting’ box below the Risk Assessment Calculator.

After harvesting – use a solid line

Follow the same procedure as above using the ‘After Harvesting’ Probability, Public Exposure, and Possible Consequences rating, and draw a solid line on the Risk Assessment Calculator. Write the Calculated Risk Score in the ‘After Harvesting’ box below the Risk Assessment Calculator.

Page 13 of 17




What risk is acceptable ?The risk is acceptable where the action of harvesting does not significantly alter the overall risk.

Acceptable outcomes Where the after harvesting line (solid line) is below or equal to the before harvesting line (dashed line) OR

Where the risk score ‘after harvesting’ is below the ‘risk acceptable’ mark.

Unacceptable outcomes

Where the After-Harvesting risk score is above the Before-Harvesting risk score, and also above the Risk Acceptable mark.

Page 14 of 17




5 Risk assessment calculator

Page 15 of 17




6 Actions arising from the outcome of the Risk Assessment Calculator

If the risk is acceptable, fill in the final section at the bottom of the front page.

If the outcome using the Risk Assessment Calculator is unacceptable (as determined on the previous page), then the operation should not proceed until a review of alternative options is undertaken. This will usually entail some further consultation with the appropriate FPA specialist.

In the case of trees retained for visual reasons beside a road, this may mean removal of some trees at the front of the screen (nearest the road), and addition of some additional trees to the back of the screen, for example. Alternatively, it may mean increasing the width of a screen o reduce the wind exposure factor.

Record below any actions taken to reduce the risk to acceptable levels, and ensure that appropriate prescriptions are placed in the forest practices plan. Re-plot the risks before and after harvesting on a new Risk Assessment Calculator sheet, label it ‘After Harvesting Modifications’, and attach it to this form.

If the risk unacceptable, indicate what action will be taken (tick one of the boxes below).

do not harvest coupe

remove hazard (e.g. harvest to road)

apply alternative harvesting approach in order to address risk

Actions taken to reduce risk to acceptable levels:

.

………………………………………………………………..........................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

.........................................................................................................................................................

Note:

a) The above may not be a complete list of all the factors that should be considered when carrying out a risk assessment for trees that are to be retained for forest practices purposes.

Page 16 of 17




b) The Forest Safety Code (Tasmania) should be referred to for information on general safety requirements

Document control log table

Document summary information

Document name Risk assessment form

Version 2.0

Trim record 2015/39019

Owner Ann La Sala and Chris Grove

Author(s) Ann La Sala and Chris Grove

Release date March 2015

Release Approved by Acting CFPO

Release status Public document

Version control

Version Date Author(s) Summary of changes

1.0 2001 FPA and WorkSafe Tasmania staff

Original version, with various edits in subsequent years

2.0 March to June 2014

Ann La Sala, Chris Grove and

Changes to form to make it more self-explanatory

Stages required for release outside FPA

Category of advice (A1, A2, B1, B2, B3 or C):

(Refer to document release protocol in 2013/17049

B1

Stages Required/not required

Completed (date)

Specialist No

Line Manager No

Peer/FPO/stakeholder review (FPA staff) No

CFPO Yes

FPAC No

Board No

Page 17 of 17



Documents

FOREST PRACTICES BOARD - fpa.tas.gov.au · Web viewPublic ExposureThe risk to the public as a consequence of a retained tree (or limb) falling onto a public place, determined by