UAVs are becoming an integrated part of contaminated land risk assessment. They provide high resolution aerial imagery and digital surface models that allow visualization of site conditions. Current uses include supplementing site walkovers, informing conceptual site models, and undertaking volume calculations. Case studies show UAVs can efficiently identify illegal waste dumping. Potential future applications include using multispectral and hyperspectral cameras to detect vegetation health issues and characterize soil and water geochemistry. This may help identify contaminant distributions and inform remediation. However, correlating spectral data with ground samples is challenging and contaminant identification capabilities are still developing. UAVs could become a common investigation tool within 5-10 years.

1. IES Embracing Data Capture Technology – 15 May 2019
Matthew Byerly, MIEnvSc CEnv
The Use of Unmanned Aerial Vehicles
(UAVs) in Contaminated Land Risk
Assessment

2. Question: Will UAV data become an integrated part
of the Contaminated Land Industry’s Digital Tools?

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Drones are ‘Taking Off’
Market Research for the Intelligent Automation sector
2022 Predictions - https://www.interactanalysis.com/drones-market-2022-predictions/

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WSP’s UAVs

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Some UAV Limitations
Area Constraint
Congested Area
limits
50m away from buildings and structures
Controlled Areas 5000m away from airports
Line of site Maximum 500m away from pilot
Weather Wind speed up to 20mph / can not operate
during rain.
Processing time
needed post-flight
to ‘stitch’ together
data
1 day for small projects (<15ha) and 2-4 days for
larger projects (15-100ha)

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− Very high resolution aerial imagery:
− Typical specification: down to 1.5cm per pixel
− Compare to Google Maps typical best at 15 cm per pixel.
− Able to capture up to 100-200 hectares in a day
Capability: High Resolution Aerial Photos
Max resolution/zoom:
Google Maps
1.5cm Resolution from UAV

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− Digital Surface Models
− Digital Terrain Model
− Vertical & horizontal
accuracy typically 2-5cm
Capability: DSM/DTMs
Cement Plant – Point Cloud Surface Model (WSP) Selected photo from dataset

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With a high-resolution aerial and digital elevation models,
you can:
− Supplement site walkovers with an eagle-eye view;
identify and target areas of concern
− Inform your CSM (e.g. identify receptors; consider
elevation differences in pathway feasibility)
− Use as background in figures, which give better context
and visualisation
− Undertake volume calculations – e.g. stockpiles,
remedial groundworks
UAVs offer considerable cost and time savings compared
to traditional survey methods.
Existing Uses for Contaminated Land Risk
Assessment

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− Illegal waste deposition in a
100-hectare former quarry site
was suspected by regulators
− Available aerial photos were
outdated and reflected when
the site was still in quarry use.
− A composite aerial photo and a
digital surface model (DSM)
accurate to 5cm were
generated following a UAV
flyover in a single day. This
data allowed for better
investigation design in review
of contemporary site
conditions.
Case Study: Confidential Former Quarry
Site, Scotland
3D Rendering of UAV aerial and elevation data

10. What does the future hold for UAVs in
Contaminated Land Risk Assessment?

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− Multispectral /
Hyperspectral
cameras
− Thermographic
cameras
− Optical Gas
Imaging cameras
Technology Compatible with UAVs - Examples
Parrot Sequoia Multispectral Sensor

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− The difference between multispectral and hyperspectral
imagery is based on how many bands they contain and
how narrow the bands are.
− Multispectral
− Hyperspectral
Source: https://gisgeography.com/multispectral-vs-hyperspectral-imagery-explained/
Multispectral / Hyperspectral cameras

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− The mining and agricultural
industries have been using
multispectral and hyperspectral
analysis for years; captured
previously through larger aircraft and
satellites.
− They now benefit from reduced costs
from having these sensors UAV-
mounted
− Affordability and availability is rising,
and other industries now stand to
benefit.
A track record of benefit in other industries

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− Vegetation Health: By analysing
different wavelengths via remote
sensing, plant health can be
determined.
− Near Infrared: vegetation strongly reflects
− Red light: vegetation strongly absorbs
− Hyperspectral analysis can quantify
soil nutrient / nutrient uptake levels.
− Fertiliser and watering requirements
can be interpreted from the data.
Agricultural Use - Examples
See https://gisgeography.com/ndvi-normalized-difference-vegetation-index/

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See: Using Drone Based Hyperspectral Analysis to
Characterize the Geochemistry of Soil and Water
James Robinson and Peter Kinghan, Journal of Geological Resource and
Engineering 6 (2018)
− Unique spectral “signatures” or “fingerprints” are given
by reflected and emitted energy of various compounds/
materials.
− The approaches and analyses have focused on
informing extraction potential and waste identification of
predominately metals and minerals relating to mining.
Mining Use – Remote Sensing of
Geochemistry

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Robinson & Kinghan 2018 – spectral
reflectance of zinc minerals

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Robinson & Kinghan 2018 – mapping of
barium concentrations in water features

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Ground Truthing
Collection of traditional samples to compare to
spectral analysis to calibrate/refine data interpretation
Collect
spectral data
Collect spatial
ground samples –
e.g.
• Soil / water
contamination
• Vegetation
nutrient levels
• Mineral
composition
Compare data sets
• What spectral bands
correspond to the ground data?
• Not always simple / direct
correlation
• Development of algorithms /
machine learning to make
sense of the data

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− Specialists are currently:
− Building libraries of the spectral signatures of
hazardous substances.
− Developing algorithms to interpret the spectral data.
− However:
− It’s presently unclear how many traditional brownfield
contaminants will be identifiable this way.
− Will we be able to ‘see’ beyond the surface?
The Possible Future for Contaminated Land

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− 1-2 years: Trials of preliminary, practical uses beyond
imagery / terrain models
− 5-10 years: Collecting spectral data will become a
common tool as part of a ground investigation
Predictions – UAVs and Contaminated Land

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Predictions – UAVs and Contaminated Land
− Robot replacement of field
staff: Hopefully not coming
as part of a dystopian future

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matthew.byerly@wsp.com
0131 344 2319
Questions?