Quotation No.: HDB000ETQ17000230 (Housing and Development Board)
QUOTATION FOR ISA CERTIFIED ARBORIST CONSULTANCY SERVICES AT DEMOLITION OF EXISTING PUBLIC HOUSING ESTATES (BATCH 9) AT BLOCKS 30 TO 32 & 34 TO 39, EXISTING SURFACE CARPARK CLAR6 AND ANCILLARY STRUCTURES AT DOVER ROAD
Company A - $29,990
Company B - $5,000 (Awarded)
Company C - $250,000
Company D - $5,000
Lowest bids are 83.3% lesser than second lowest bid.
Highest bid is 50 times (5000%) more than lowest bids.
Quotation No.: HDB000ETQ17000332 (Housing and Development Board)
QUOTATION FOR ISA CERTIFIED ARBORIST FOR CONSULTANCY SERVICES, SURVEYING & RECOMMENDATION FOR NPARKS SUBMISSION FOR THE PROPOSED PUBLIC HOUSING DEVELOPMENT AT CHOA CHU KANG N1C16
Company A - $4,200
Company B - $2,900
Company C - $1,500 (Awarded)
Lowest bid is 64% lesser than highest bid.
Quotation No.: JTC000ETQ17000074 (Jurong Town Corporation)
Provision of Certified Arborist for Tree Species Identification, Value and Risk Assessment Services
Company A - $28,000
Company B - $27.50
Company C - $12,000
Company D - $55,640,000
Company E - $35,000
Company F - $13,800 (Awarded)
Quantity is 1000 nos... maybe the confusion over the quantity lead to some strange quotes here.
After adjustment, Company B's figure may be $27,500 and Company D's figure may be $55,640. Either way, Company F's figure was the second lowest of all, and was awarded the work. The lowest was Company C.
Saturday, September 23, 2017
Friday, September 1, 2017
Resistograph or sometimes known as Resistance Drilling Device
On Jul 2013, two Tembusu trees were observed to be not doing well and to be clear, these tree are not in the Singapore Botanic Garden. The trees have low density of foliage, and the ground within the dripline was compacted, as evidenced by absence of groundcover. Target is the carpark and cars that were parked there, occasional park visitors.
Crown area and trunk of the two Tembusu trees.
On Sep 2013, vertical mulching was done to break up the hardpan surface and to pour in used coffee grinds (organic matter) and NPK 15-15-15 (fertiliser).
Making vertical holes.
Overall view of the vertical holes filled with organic matter and fertiliser.
On Oct 2013, the tree on the left was observed to be still low in leaf density but the tree on the right had put out more leaves.
On Jan 2014, the pruning was done by the arboriculture contractor to remove dead branches.
On the same day, I was inspecting the work of the arboriculture contractor and also found that there is a possible cavity below the union of the tree (the tree on the left).
The extent of decay below the union, if any, was needed to be determined in order to ascertain whether the tree is safe. The depression may just be a natural pocket formed by V-shaped point of union. Hence, a request was sent out for quotations from arborists with resistograph or Resistance Drilling Device. The scope of work was of course to have the resistograph work done, first level tree assessment before that, and reports for both. The works were to be carried out at ground level, and three arborists came up with fees of $1800, $1500 and $1100, respectively.
A "Resi" or Resistance Drilling Device that is used to detect cavities in wood, which is a sign of decay. The company that manufactures this particular device, IML, could not use Resistograph to describe its device in some jurisdictions as the term was trademarked by another company, Rinntech.
The resistograph work was done on Feb 2014 and should be done again in 2 years to see if there is spread of the decay, if any.
On Sep 2013, vertical mulching was done to break up the hardpan surface and to pour in used coffee grinds (organic matter) and NPK 15-15-15 (fertiliser).
The extent of decay below the union, if any, was needed to be determined in order to ascertain whether the tree is safe. The depression may just be a natural pocket formed by V-shaped point of union. Hence, a request was sent out for quotations from arborists with resistograph or Resistance Drilling Device. The scope of work was of course to have the resistograph work done, first level tree assessment before that, and reports for both. The works were to be carried out at ground level, and three arborists came up with fees of $1800, $1500 and $1100, respectively.
The resistograph work was done on Feb 2014 and should be done again in 2 years to see if there is spread of the decay, if any.
The Curious Incident of the Tembusu Tree that Fell
On 17 Jul 2017, two independent arborists testified at a Coroner’s Inquiry on the death of Radhika Angara, a mother of two who was killed when a Tembusu tree fell on her at Singapore Botanic Garden.
One of the expert witnesses, Derek Yap, an arborist with Camphora said that the tree had "no visible signs of crack and cavities", based on his inspection after the tree fell and information preceeding the incident. In addition, he said that "about 70 per cent of the tree trunk at its 2m point was decayed". That extent of decay would significantly reduce the structural condition of the tree but the decay could not be observed from the outside of the tree.
A news article was published yesterday with the headline of "NParks disputes arborists’ diagnosis on tembusu tree in fatal incident" (Today Online, 31 Aug 2017).
A National Parks Board (NParks) representative, deputy director Elango Velautham, testified on 30 Aug 2017 that a 1.5m long "cavity" found during an inspection done on Sep 2016 was actually a "flute" (see definition below) This statement raises three points to be noted:
1. The inspection done on Sep 2016 was by NParks officers.
2. One of the independent arborist said that the tree had "no visible signs of crack and cavities" in his testimony on 17 Jul 2017.
3. It was not known whether the misdiagnosis was discovered before or after the tree fell.
The news article suggested that Elango's testimony contrasted with that of the two independent arborists. But could it be that his testimony actually supported the two independent arborists'?
Elango said that NParks arborists have written a statement to note that the flute was "wrongly perceived as a cavity" as a follow-up to the Sep 2016 inspection report. But it was not known whether the misdiagnosis was discovered before or after the tree fell.
The lawyer acting for Angara's family had questioned "the absence of documentary proof showing how the misdiagnosis was determined", as the written statement was not produced in court on 31 Aug 2017. If signs of decay (cavity) was observed from visual tree assessments, both independent arborists "agreed that further tests such as resistograph and ultrasound could be used to detect decay".
Bonus Curious Point
Arborist Derek Yap agreed that the roots might have been cut and leading to possible decay but another arborist, Richard Gordon Thomas from ArborCulture, said it was not clear that root had been cut. However, another news article - "Tembusu tree accident: Botanic Gardens official says there was 'no decay, no cavity'" (Channel NewsAsia, 30 Aug 2017) - mentioned that both arborists "agreed that the tree’s roots were in decay".
Bonus Bonus Curious Points
That same news article mentioned above wrote that Elango described a flute to be a “protruding structure” on a tree’s trunk formed in response to “environmental exertions” to the tree. Could it be that the journalist who wrote that or Elango confuse a flute with buttress roots?
Elango added that a Temusu tree is "very slow growing", and decays would "take a very long time to … destabilise a tree". Does he mean to suggest that the spread of decay is in pace with the growth of wood?
The structural stability of the tree would be impacted if the decay was extensive enough, in spite of the wood strength.
References
1. Tembusu tree that killed woman had no visible signs of decay, Today Online, 18 Jul 2017
2. NParks disputes arborists’ diagnosis on tembusu tree in fatal incident, Today Online, 31 Aug 2017
3. Tembusu tree accident: Botanic Gardens official says there was 'no decay, no cavity', Channel NewsAsia, 30 Aug 2017
One of the expert witnesses, Derek Yap, an arborist with Camphora said that the tree had "no visible signs of crack and cavities", based on his inspection after the tree fell and information preceeding the incident. In addition, he said that "about 70 per cent of the tree trunk at its 2m point was decayed". That extent of decay would significantly reduce the structural condition of the tree but the decay could not be observed from the outside of the tree.
A news article was published yesterday with the headline of "NParks disputes arborists’ diagnosis on tembusu tree in fatal incident" (Today Online, 31 Aug 2017).
A National Parks Board (NParks) representative, deputy director Elango Velautham, testified on 30 Aug 2017 that a 1.5m long "cavity" found during an inspection done on Sep 2016 was actually a "flute" (see definition below) This statement raises three points to be noted:
1. The inspection done on Sep 2016 was by NParks officers.
2. One of the independent arborist said that the tree had "no visible signs of crack and cavities" in his testimony on 17 Jul 2017.
3. It was not known whether the misdiagnosis was discovered before or after the tree fell.
Definition of a "flute".
An example of "flutes" - the grooves between buttress roots below the feet of the arborist on the tree. Photo credit: Today Online
The news article suggested that Elango's testimony contrasted with that of the two independent arborists. But could it be that his testimony actually supported the two independent arborists'?
Elango said that NParks arborists have written a statement to note that the flute was "wrongly perceived as a cavity" as a follow-up to the Sep 2016 inspection report. But it was not known whether the misdiagnosis was discovered before or after the tree fell.
The lawyer acting for Angara's family had questioned "the absence of documentary proof showing how the misdiagnosis was determined", as the written statement was not produced in court on 31 Aug 2017. If signs of decay (cavity) was observed from visual tree assessments, both independent arborists "agreed that further tests such as resistograph and ultrasound could be used to detect decay".
Bonus Curious Point
Arborist Derek Yap agreed that the roots might have been cut and leading to possible decay but another arborist, Richard Gordon Thomas from ArborCulture, said it was not clear that root had been cut. However, another news article - "Tembusu tree accident: Botanic Gardens official says there was 'no decay, no cavity'" (Channel NewsAsia, 30 Aug 2017) - mentioned that both arborists "agreed that the tree’s roots were in decay".
Bonus Bonus Curious Points
That same news article mentioned above wrote that Elango described a flute to be a “protruding structure” on a tree’s trunk formed in response to “environmental exertions” to the tree. Could it be that the journalist who wrote that or Elango confuse a flute with buttress roots?
Elango added that a Temusu tree is "very slow growing", and decays would "take a very long time to … destabilise a tree". Does he mean to suggest that the spread of decay is in pace with the growth of wood?
The structural stability of the tree would be impacted if the decay was extensive enough, in spite of the wood strength.
References
1. Tembusu tree that killed woman had no visible signs of decay, Today Online, 18 Jul 2017
2. NParks disputes arborists’ diagnosis on tembusu tree in fatal incident, Today Online, 31 Aug 2017
3. Tembusu tree accident: Botanic Gardens official says there was 'no decay, no cavity', Channel NewsAsia, 30 Aug 2017
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