COVID-19 SERVICES UPDATE: Information for all alert levels, Waka Kotahi services and more

SCAM ALERTS: Report a phishing scam or learn about the latest phishing emails

ONLINE SERVICES: We currently have an issue with receiving some payments and are working to resolve this issue as quickly as possible. We apologise for any inconvenience.

EASTER WEEKEND – PLAN AHEAD: Heading away for the long weekend? Check our holiday journeys tool(external link)

SCAM ALERTS: Refund email and Vehicle licence (rego) renewal phishing emails

Back to Resources

Research Report 345 Contaminant characterisation and toxicity of road sweepings and catchpit sediments: towards more sustainable reuse options

Published: | Category: Environmental impacts of land transport , Research programme , Research & reports | Audience: General

In 2006–2007, 35 road-derived sediments (RDS) consisting of street sweepings and catchpit (ie sump) sediments, were collected from three cities in New Zealand; namely Auckland, Hamilton and Christchurch. The concentrations, mobility and toxicity of contaminants were determined in order to assess the suitability of RDS for certain reuse applications. The current situation in New Zealand is that all RDS must be disposed of in landfills. The RDS were analysed for total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs) and the heavy metals, lead, copper and zinc – with respective median (n=35) concentrations of 1220, 6.3, 122, 67, 422 μg/g. Comparisons with soil guideline values for ecological protection (Dutch and Canadian) and reuse of biosolids for land application (New Zealand), indicated that zinc will be the most problematic contaminant with respect to mitigating environmental risks in any reuse applications of RDS in New Zealand. Selected RDS freshwater leachates were toxic to the alga, Psuedokirchneriella subcapitata, at zinc concentrations of ca. 22-150 μg/L (EC50), however, leachate toxicity was reduced up to 225-fold when amended, or ‘stabilised’ with 10% compost. Based on the results and potentially applicable guideline values, the reuse of RDS may be limited to applications that either physically (ie incorporation into concrete or asphalt) or chemically (ie addition of a ‘stabilising’ agents like compost or phosphate) immobilise problematic heavy metal contaminants, namely zinc.

Publication details

  • Author:
  • Published: May 2008
  • Reference: 345
  • ISBN/ISSN: ISBN 978-0-478-30970-6 ISSN 1177-0600