Report Regarding Lyn Christie Housing Complex
22 November 2001
Release Of Report Regarding Lyn Christie Housing Complex
Christchurch City Council today presented tenants of Lyn Christie Place Housing Complex with a comprehensive report regarding the housing complex and the land upon which it is built, following investigations of the site.
The report was written by Environmental Scientists, Montgomery Watson Harza, who have been conducting investigations of Lyn Christie Place for the Council over recent months.
Lyn Christie Place provides housing at low cost for 27 tenants. The complex was built in the 1970's by Christchurch City Council. The site is thought to have been used as a landfill in the early 1940's.
Please see the attached documents:
1. Statement provided by Rob Dally, Property Manager, Christchurch City Council (3 pages).
2. Executive Summary of the report produced by Environmental Scientists, Montgomery Watson Harza (1 page).
Further information: Rob Dally, Property Manager, Christchurch City Council, ph: 379 1660 extension 8500
Thursday, 22 November 2001
COUNCIL STATEMENT: INVESTIGATIONS OF LYN CHRISTIE PLACE
Statement by: Rob Dally, Property Manager, Christchurch City Council
In August 2001, Christchurch City Council initiated some investigations on the Lyn Christie Place Housing Complex, and land upon which it is built. Preliminary investigations were undertaken as part of the Council's processes to manage its property assets, and further tests were conducted following indications that some contaminants were present on site.
Environmental Scientists, Montgomery Watson Harza, conducted the investigations of Lyn Christie Place. A comprehensive report has been produced by them, including recommendations for the Council to take certain actions.
Please find attached a copy of the executive summary of Montgomery Watson Harza's report. A full copy of this report can be obtained from the Property Unit of Christchurch City Council (Civic Offices, Tuam St).
Montgomery Watson Harza have stated in their report to the Council that:
1. Settling of floors exists in some units. However, structurally, the buildings are satisfactory from a health and safety perspective.
2. Very low(trace) levels of methane gas is detectable in some places below the ground and in some units. There is no concern about health and safety due to this.
3. Soil samples identified elevated levels of polycyclic aromatic hydrocarbons (PAHs) and heavy metals that exceed the relevant guidelines.
4. Shallow groundwater flow direction underneath the site is variable. Water quality testing identified elevated levels of arsenic, ammonia, manganese, iron and boron, when compared to New Zealand drinking water standards.
(Please note that the groundwater system beneath Lyn Christie Place is stratified into several aquifers separated by clay layers. Drinking water is not drawn from shallow groundwater (less than 15m). Water supplied to Christchurch households comes from deeper, protected aquifers. In the Linwood/Wainoni area the shallowest public water supply aquifer is approximately 130m below the ground surface).
Montgomery Watson Harza have reported (p35) that "the concentrations detected in the groundwater below Lyn Christie Place do not pose a risk to human health given that the local supply is derived from the city's reticulated drinking water system, which originates from deeper bores" and (p28) that "the offsite movement of groundwater does not provide a significant risk to human health or environment above that of comparable urban, shallow groundwater in this part of the city ".
Recommendations provided by Montgomery Watson Harza, ratified by Environment Canterbury and Crown Public Health, to remediate the issues identified at Lyn Christie, are listed below. The Council's decision relating to each recommendation follows in italics.
Recommendation: Raise the floor of each unit to restrict damage from settling, by injecting resins.
* (The Council will trial the injection of resins underneath the floors to restrict damage from settling)
Recommendation: Undertake a further one-off test for Landfill Gas (LFG) before the end of this year (p22).
* (The Council will undertake a further one-off test for LFG within this timeframe)
Recommendation: Removal and replacement of designated areas of soil, in order to minimise tenants' exposure to contaminants (p15).
* (The Council will remove all soil in garden areas to a minimum depth of 500mm, and replace it with clean material. Tenants will be compensated for loss of vegetables currently growing).
* (The Council will install an irrigation system for the grass lawn area in order to maintain healthy grass cover).
Recommendation: Develop a specific Remedial Action Plan / Site Management Plan for the property and housing complex (p16).
* (The Council will develop a comprehensive Remedial Action Plan and Site Management Plan for Lyn Christie Place and the land upon which it is built. Procedures included in the plans will ensure the health and safety of the tenants and workers at Lyn Christie Place throughout remediation process and afterwards).
The Council is strongly committed to providing our tenants with a healthy and safe environment in which to live, and to providing current and accurate information about the issues as we become informed ourselves.
We have carefully carried out the investigations of the Lyn Christie Place, and worked in close consultation with Crown Public Health and Environment Canterbury to identify the issues and work towards appropriate solutions.
Dr Mel Brieseman, Medical Officer of Crown Public Health, has made the following statement regarding Lyn Christie Place:
"I have considered the matters raised in the 'Lyn Christie Place Site Investigation' report to the Christchurch City Council produced by Montgomery Watson Harza and discussed the issues with those involved. I feel that the issues involved are well covered and that if the recommendations made in the report are implemented the site will not constitute a risk to human health".
Helen Davies, Senior Contaminated Sites Officer of Environment Canterbury, has made the following statement regarding Lyn Christie Place:
"I have been kept informed of the investigative work conducted at Lyn Christie Place. The assessment of results, and the discussions held with involved parties about future work indicate that environmental concerns are being addressed in a responsible way".
What will happen next?
* Housing Officer John MacDonald will visit each tenant to establish the quantity of vegetables to be removed, so that compensation can be arranged.
* Replacement of garden soil will begin in the next fortnight. The Council aims to have all garden areas remediated early in 2002.
Any questions regarding this statement should be directed to the following
Tenants enquiries: John MacDonald , Housing Officer, on 379 1660 extension 8519, or on his mobile phone (025) 372 077.
Media: Rob Dally, Property Manager, Christchurch City Council, ph: 379 1660 extension 8500.
Lyn Christie Place Site Investigation November 2001
* MWH Ltd carried out an initial site investigation of Lyn Christie Place in August 2001. This involved a structural assessment of two vacant units, the installation of two landfill gas wells and some limited soil sampling.
* Trace concentrations of landfill gas (LFG) were detected in the subsurface of the property
* The soil samples identified elevated levels of polycyclic aromatic hydrocarbons (PAHs) and associated heavy metals above the values presented in the Guidelines for Assessing and Managing Contaminated Gasworks Sites. Of particular concern is benzo[a]pyrene (BAP).
* Additional soil samples were collected in September and October confirming the presence of BAP at concentrations that exceed the relevant guidelines.
* Each housing unit was sampled for the presence of LFG however any detectable concentrations did not present a health and safety risk to residents.
* Structural assessments of each housing unit showed that settlement issues are continuing. The degree of damage being caused is variable from unit to unit however there are no health and safety concerns.
* Two designated groundwater monitoring wells were installed on the property for the purpose of assessing groundwater quality.
* Groundwater flow direction is variable within the unconfined shallow aquifer at Lyn Christie Place.
* Water quality sampling results have identified elevated arsenic, ammonia, manganese, iron and boron when compared to the Drinking Water Standards for New Zealand (2000). However, the concentrations detected in the groundwater below Lyn Christie Place do not pose a risk to human health given that the local water supply is derived from the City's reticulated drinking water system, which originates from deeper bores.
* Remedial action has been recommended that will minimise/eliminate contaminant exposure pathways available to residents at Lyn Christie Place.
* The preferred remedial options to deal with the elevated concentrations of soil contaminants and structural damage include: 1) striping and replacing with clean material designated areas of soil that will minimise the exposure pathways to residents and 2) to inject resins that will raise the floor of each unit and restrict damage from settling.
Montgomery Watson Harza Ltd