Macdonald, Garry

Garry Macdonald is widely recognised as an expert in wastewater engineering with over 48 years' experience in a wide variety of wastewater and...

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About Macdonald, Garry

Garry Macdonald is widely recognised as an expert in wastewater engineering with over 48 years' experience in a wide variety of wastewater and environmental projects, both in New Zealand and abroad. He has a high-profile involvement in many industry organisations, including WEF and its MA, Water NZ. Garry has held project leadership roles in most of the major wastewater projects carried out by Beca in the last 34 years, including for Gisborne District Council which is the subject of this WEFTEC presentation. He is a WEF Fellow and has received a number of prestigious industry awards and presented over 65 technical papers in industry publications and at conferences in NZ, Australia, and USA.

Macdonald, Garry

Titles from this speaker

Bioboost Mark II: Decarbonizing Biosolids Drying using Hydrogen

Abstract

The New Plymouth Wastewater Treatment Plant (WWTP) is owned and operated by New Plymouth District Council (NPDC or Council), and services approximately 87,000 people. Since 2002, Council has achieved close to 100% beneficial reuse of their biosolids by selling them as a granular fertilizer product Bioboost®. The current dryer is a rotary drum dryer, fueled by natural gas, and was the first such dryer installed in New Zealand. This paper looks at the critical success factors for Bioboost® and also explores the question “where to next?”, as the thermal dryer which produces Bioboost® reaches its end of life, and is replaced in a new facility with a larger drum dryer, partially fuelled by hydrogen

The New Plymouth District Council (NPDC) dries its biosolids in a thermal drum dryer, fuelled by natural gas. The dried pellets are marketed as a fertiliser, trademarked as BioboostÂ®. The existing dryer has reached the end of its service life and needs replacing. In assessing replacement options, NPDC decided to build a new facility around a larger drum dryer, but decided that it should be duel-fired, with 25% of the energy demand met by a new hydrogen supply to reduce its carbon footprint.

SpeakerMacdonald, Garry

Presentation time

16:00:00

16:20:00

Session time

15:30:00

17:00:00

SessionFull-scale Thermal Drying System Implementation

Session locationRoom S501d - Level 5

TopicAdvanced Level, Energy Production, Conservation, and Management, PFAS, Sustainability and Climate Change

Author(s)

Macdonald, Garry

Author(s)G. Macdonald 1; J. Daly 2 ; M. Hall 3; G. Morris 3; G. Macdonald 1;

Author affiliation(s)Beca Ltd, Auckland, New Zealand 1; Beca Ltd, Auckland, New Zealand 2 ; New Plymouth District Council, Taranaki, New Zealand 3; New Plymouth District Council, Taranaki, New Zealand 3; Beca Ltd, Auckland, New Zealand 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159029

Volume / Issue

Content sourceWEFTEC

Word count9

Infrastructure Resilience in the Face of Extreme Weather Events: 'Domino Effect'

Abstract

INTRODUCTION Many communities around the world are facing unexpected and compounding impacts from extreme weather events, driven by climate change and changing weather patterns. Infrastructure — particularly water, wastewater and stormwater assets — designed on the basis of historical events and existing climate records is being found to be highly prone to catastrophic failure, often with a 'domino' effect on other assets and the health and welfare of the communities served. This paper will cover the catastrophic impacts of a major tropical mega-storm — Cyclone Gabrielle — which impacted the east coast of the north island of New Zealand in March 2023 (Refer Figure 1 for location map and Figure 2 for weather map). This brought some of the highest rainfall intensities, river flows and winds that the country has ever experienced in over 250 years of European settlement and recorded data. The paper will highlight the compounding impacts of the cyclonic event on the region's water systems, and how existing land use policies and practices (forestry, horticulture, agriculture and urban development) contributed negatively to the devastating outcomes of this storm event. HISTORICAL BACKGROUND Cyclone Gabrielle is not the first major tropical storm to hit this region. In 1988, a similar weather system generated Cyclone Bola (see Figure 3) which caused widespread land slips and river overflows in the Gisborne region. Farmland and forestry lands were devastated as natural vegetation was swept away by the slips and in erosion by floodwaters. As part of the recovery, a government-funded regional forestry replanting project was instigated — using pine trees — to stabilise the slopes and create a long-term economic benefit once the pine trees were harvested. It should be noted that pre-European settlement and introduction of primary industries to the region — primarily sheep and beef raising — most of these hills were covered in native forests which were felled and replanted with grass for grazing. COMPOUNDING CONSEQUENCES OF 2023 EVENT — THE 'DOMINO EFFECT' Unfortunately, some 35 years later, this Bola recovery project was one of the root causes for the widespread damage caused by Cyclone Gabrielle. Plantation tree husbandry practices left much of the branches (referred to as slash) on the ground, to be swept off the steep slopes into the flooded rivers, sweeping downstream to destroy or block bridges and destroy utility services carried by the bridges. The 30km long main water supply to Gisborne City (40,000 population) was destroyed in a number of locations, cutting off this supply for six weeks. The shallow-rooted pines were easily uprooted and swept into the flooded rivers, adding to the volume of slash, and ultimately ending up on the regions beaches as mountains of woody debris. The accompanying silt and soil loads from the now naked and destabilised hill country blanketed low lying productive land (vineyards, kiwifruit and citrus plantations, and vegetable farms), ruining the majority of the current seasonal crops either being or about to be harvested. The knock-on economic and social impacts on the whole region have been huge as it relies very heavily on the agricultural and horticultural industries. The silt blanketing the land did not finish there, as the rivers carried the huge volumes of silt into the nearshore ocean waters, smothering the easily accessible seashore and seabed from which many forms of marine life have been harvested as a traditional indigenous food source. An unanticipated outcome of this impact was the increased cost of living for many sections of the Gisborne community who relied on this readily available food source. While the city's wastewater system was overwhelmed by the heavy rain, with many system overflows to the three rivers running through the city, there was little long-term damage to the network or the wastewater treatment plant — even though the latter was in the middle of a major upgrade. The telecommunication network was not so lucky, with cell towers knocked out or without power, with Starlink satellite phones being the only viable alternative once enough were procured and distributed to essential lifeline services. Major damage occurred to the roading network, through the loss of many bridges and massive wash-outs, which severely limited local and regional transport of emergency services and maintenance crews and equipment LESSONS LEARNED With the Cyclone Gabrielle response well in the past, regional public and private sector leadership is now working in the recovery phase with support from central NZ government. Everyone involved realises that similar or even worse cyclones will hit again, driven by changes in the wider Pacific weather systems, driven by global climate change. Revegetating and restabilising the steep hill country is essential, but it is unlikely to see replanting of the pine plantations, focussing instead on a greater diversity of tree and shrub species. The resilience of water supply assets is being addressed, including more appropriate carriage of water supply pipes (and other utilities) over rivers subject to flooding. It is impossible for communities and individuals to insure against the scale of losses and damages incurred by the Gisborne region; the best investment is to envisage the very worst that can happen and to plan accordingly, fully recognising the 'knock-on' or 'domino impacts' that these mega-events can produce.

Climate change is impacting every country in the world, bringing a wide range of extreme weather events that are challenging infrastructure, populations and economies, often with devastating consequences. Cyclone Gabrielle was the worst extreme weather event to hit New Zealand in living memory, causing catastrophic damage to infrastructure and utility services over a wide region. Much can be learned by communicating about such 'domino effects' so that others globally can plan accordingly.

SpeakerMacdonald, Garry

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionResilient Solutions in Response to Nature's Forces

Session number423

Session locationRoom 335

TopicClimate Change Adaptation and Metrics, Intermediate Level, Resilience, Safety, and Disaster Planning, Stormwater and Green Infrastructure

Author(s)

Macdonald, Garry, Wilson, David

Author(s)G.J. Macdonald1, D.R. Wilson2

Author affiliation(s)1Beca Ltd, AUC, 2Te Amokura Ltd

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159596

Volume / Issue

Content sourceWEFTEC

Word count12

Planning a Resilient Wastewater System: From Beginning to End

Abstract

Tauranga is a medium sized coastal city of 141,000 people, located in the fast-growing Bay of Plenty region of New Zealand. The city is served by two wastewater treatment plants, which are unusual in that they are connected at both the beginning and end of the trunk collection and conveyance system. The treatment plants are located at sea level and are subject to coastal and seismic hazards. Significant upgrades are required in the short, medium and long term to accommodate population growth and improve resilience to natural hazards and the effects of climate change. Tauranga City Council and Beca have worked together over the past five years to plan, design and construct wastewater upgrades to cater for growth and improve operational and natural hazard resilience. This paper describes how staged planning for operational and natural hazard resilience has led to better community outcomes for the Tauranga community.

SpeakerMacdonald, Garry

Presentation time

09:30:00

09:50:00

Session time

08:30:00

10:30:00

SessionResilience for the Future: Designing Water and Wastewater Infrastructure for Resilience Against Intensifying Extreme Weather Events

Session number329

TopicPolicy and Regulation, Sustainability and Climate Change, Urban Systems

Author(s)

W.J. PottsK. HermensG. Macdonald

Author(s)W.J. Potts1; K. Hermens2; G. Macdonald2;

Author affiliation(s)Tauranga City Council1; Beca2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157873

Volume / Issue

Content sourceWEFTEC

Word count10

Putting the Screws on Non-Stabilized WAS: A Kiwi Experience

Abstract

The Te Maunga WWTP is one of two plants servicing Tauranga (population 150,000), New Zealand. Since commissioning in 1997, waste activated sludge (WAS) has been partially stabilised in an adjacent pond. A condition in the latest permits for the WWTP required the pond to be decommissioned. An options study was undertaken to select WAS thickening and dewatering equipment to be installed. At concept design, gravity belt thickeners and screw presses were chosen as the preferred thickening and dewatering technologies respectively. As screw presses are a relatively new technology in NZ wastewater treatment plants, and WAS without any primary sludge is difficult to dewater, dewatering trials were undertaken. Based on the pilot trials, picket fence thickeners were chosen over GBTs and two screw presses were installed in a new dewatering building, along with ancillary plant. The project and results from the pilot trials and full-scale operation are presented in this paper.

SpeakerMacdonald, Garry

Presentation time

10:50:00

11:10:00

Session time

10:30:00

11:30:00

SessionOvercoming Dewatering Difficulties

Session number520

TopicBiosolids and Residuals, Facility Operations and Maintenance

Author(s)

G.J. MacdonaldG.J. MacdonaldW.J. PottsJ. Daly

Author(s)G.J. Macdonald1; G.J. Macdonald1; W.J. Potts2; J. Daly1;

Author affiliation(s)Beca Ltd, Auckland1; Tauranga City Council, Bay of Plenty2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157543

Volume / Issue

Content sourceWEFTEC

Word count10

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Macdonald, Garry

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