A Water Quality Risk Assessment Procedure for. Infrastructure Projects. *Presenting Author

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1 A Water Quality Risk Assessment Procedure for Infrastructure Projects David J Kemp* 1, Anne Welsh 2, Matthew Jones 3 and Catherine Gray 4 *Presenting Author The South Australian Department of Planning, Transport and Infrastructure has developed a water quality risk assessment procedure for transport infrastructure projects, based on AS/NZS and Austroads risk assessment methodology, that determines treatments to be used to address water quality risks, and performance targets that have to be met by the treatments. By this means, the Department can provide evidence that reasonable and practicable measures are being taken to minimise environmental harm, as required by the Environment Protection Act, T I. Introduction HE Department of Planning, Transport and Infrastructure (DPTI) in South Australia manages a significant on-going investment in public infrastructure. The Transport Services Division of the Department has responsibility for the maintenance and operation of the state s transport network and regulation of its use, 1 University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, 5095, david.kemp@unisa.edu.au 2 Department of Planning, Transport and Infrastructure, GPO Box 1533, Adelaide 5001, anne.welsh@sa.gov.au 3 Department of Planning, Transport and Infrastructure, GPO Box 1533, Adelaide 5001, matthew.jones@sa.gov.au 4 Department of Planning, Transport and Infrastructure, GPO Box 1533, Adelaide 5001, catherine.gray@sa.gov.au 1

2 and the delivery of major infrastructure projects. Under South Australian environmental legislation there is a general environmental duty. Part 4 of the Environment Protection Act, 1993 requires that [a] person must not undertake an activity that pollutes, or might pollute, the environment unless the person takes all reasonable and practicable measures to prevent or minimise any resulting environmental harm. The use of a risk assessment procedure can demonstrate that reasonable and practicable measures are being undertaken to minimise environmental harm. In the Department the process is known as Water Quality Risk Assessment (WQRA). It is documented as part of the DPTI Protecting Waterways Manual, and is available on line on the DPTI website (DPTI, 2012a). II. Risk Management The South Australian Government Risk Management Policy Statement recognises that commitment to risk management contributes to sound management practice and increasing community confidence in government performance (DPTI, 2013). The Departmental Risk Management Policy DP086 (DPTI, 2013) defines a common risk management approach to be used across the department in accordance with statutory obligations and consistent with AS/NZS ISO31000:2009 Risk Management Standard. Risk management is an integral component of management frameworks that apply to the Department s activities, such as the Financial Management Framework, the Prudential Management Framework, Treasurers Instructions, the Project Management Framework, the Procurement Reform Strategy (Purchasing Strategically) and Work Health and Safety (DPTI, 2013). Risk management is applied to all spheres of organisational planning and management, including environmental management, to ensure that key risks are being addressed. Risk assessment addresses the causes and effects of potential environmental harm and evaluates risk treatments so that the most appropriate measures are identified and expenditure can be prioritised. A risk assessment is undertaken to determine the potential nature, scale and likelihood of any impacts during both the construction phase and the operational use of the infrastructure. Consideration should be given 2

3 to the potential impacts of staged earthworks; of altered surface or groundwater hydrology and drainage paths; to the pollutants in road runoff; and the likelihood and potential impact of any spills of hazardous materials. The process used for environmental risk assessment follows the generic framework in AS/NZS 4360:1999 Risk Management and as further developed by Austroads (2001) in Environmental Risk Management Guidelines and Tools for Road Projects. The main steps in the risk management process are to: Establish the context. Identify risks. Analyse risks. Evaluate risks. Treat risks. There is some iteration in the process, or feedback loops that are required to ensure that the overall project can proceed with an acceptable level of risk. A. Establish the context The nature and scale of projects vary widely. A 'scan' is undertaken for each project, to help define the scope of the risk management process. Things that should be considered include: The purpose and nature of the project. Legislative compliance requirements - for example, some activities are prescribed in legislation and are subject to approvals and licence conditions. The probability of discharge of sediment laden wastewater from earthworks. The water quality objectives or strategic directions for the catchment, including those contained within any relevant catchment plan. Particular environmental concerns raised by the local community. 3

4 Criteria for acceptance of risk should be understood or determined. These will involve considerations of cost as well as opportunities. What measures can be included with little expense? How much effort does the potential scale of impacts of the project warrant? What are community expectations? B. Identify Risks This step is applied to all projects, large or small, and may need to be an iterative process as more information becomes available or adjustments to the project are made. It can be undertaken as a brainstorming exercise. Every conceivable environmental risk arising from the project should be recorded, as prompted by answers given to the key questions: What can happen? How and why can it happen? The risk is identified as a potential impact or event caused by the construction or operation of the project. In the case of road projects this will generally be caused by the export of pollutants, for instance heavy metals, nutrients or sediment. Other potential risks arise from any change in downstream flow regime (volume, peak flow and flow duration) as a result of the project. Risk identification may require input from many areas and other agencies or stakeholders. Various tools are available to obtain input to the process, ranging from consultation to risk management workshops. An appropriate tool for risk identification and management during the remainder of the process should be selected to suit the scale and potential environmental impact associated with the project. The owners of risks identified during this process should be documented together with the names of those considered to be accountable and responsible for the management of the risk. These may or may not be the same. The aspects listed below should be considered in identifying risks: 1. Site Characteristics The topography of the site. The nature and erodibility of the soils (including potential acid sulfate soils). 4

5 Climate and rainfall patterns. The drainage pattern and size of catchments The quality and nature of receiving waters e.g. a water supply reservoir, recreational water body, or protected marine area. The quality and depth to groundwater and any pollution transport mechanisms The vegetation and ecology of the site and surrounding area, including the downstream aquatic environment for example important wetlands, aquatic habitat, rare or endangered flora or fauna, or other significant area. The land use of the adjacent and downstream areas. The nature and capabilities of any water quality treatment measures already in place downstream of the project area. 2. Project Characteristics The timing and scale of the project. Any proposed staging of the project, including the area to be opened for work at any one time The extent of cut and fill. The volume and nature of traffic, extent of commercial vehicles or hazardous loads. Potential traffic accident characteristics. Concentration or dispersion of stormwater, changing the nature, timing and location and quality of flows or altering flood patterns. The effect of the project on any water quality treatment measures already in place downstream of the project area. Impediments to achieving any water quality objectives for the catchment 5

6 C. Analyse risks Risk Analysis is accomplished through examination of all the previously identified risks in relation to two questions: How likely is it to happen? What could be the consequences if it does happen? The information about the site and the project is examined again to answer these questions. In making these judgments about likelihood, it is useful to recognise that some of the factors are not influencing absolute probability as much as relativity. As examples; a steep ground slope will be more likely to scour than a horizontal surface. Erosion is more likely to occur if areas are disturbed during the wet season than in the dry. The likelihood of risk will relate to aspects such as the volume and nature of the traffic, the potential pollutant sources and the potential increase in the volume of runoff and peak flows contributing to the erosion potential. The consequences or impacts of a particular polluting occurrence depend on the nature of the receiving environment. For example, run-off from an urban arterial road may be piped through urban drains into an established wetland that provides effective pollution treatment prior to the stormwater entering the marine environment, or alternatively, may flow directly into a watercourse of high value. For a given pollution event, the consequences (or impacts) of such an event in different locations may be quite varied. Table 1 is the matrix used to analyse the risks. 6

7 Table 1. Qualitative Risk Analysis Matrix. Consequence Low Medium High Minor adverse social Measurable adverse Significant damage or Likelihood or environmental environmental or impact on impact. social impact. Will environmental result in annoyance or systems and local nuisance to community. community Low The event could occur only rarely, or is unlikely to occur Low Risk Low Risk Medium Risk (could be High) Medium The event will occur occasionally or could occur Low Risk Medium Risk High Risk High The event will occur often or is most likely to occur Medium Risk High Risk High Risk (Critical) D. Treat risks Detailed consideration of specific treatment measures to address risks requires answers to the following questions: How effective are any existing mitigation measures? Are the criteria set in the first step - 'establish the context' satisfied by them? If not, what additional treatments are available and how effective would they be in reducing the risk to an acceptable level? 7

8 Are the additional measures reasonable and practicable? Are the criteria set in the first step - 'establish the context' satisfied by the measures? Table 2 contains information on the appropriate treatment response to each identified risk level. Table 2. Indication of risk based treatment response. Level of Risk Proposed Level of Treatment Critical Ensure appropriate treatment methods adopted and/ or consider alternative project options or road or rail alignments, to reduce the level of risk. Cost of treatment should not be the primary consideration. High Ensure an integrated stakeholder approach and risk management plan in place. Cost of treatment should not be the primary consideration. A range of treatments should be applied to the site (treatment train approach). Design of treatments should be based on a judicious, precautionary application of design procedures. Medium Cost of treatments may be considered. Select in conjunction with the most suitable measures for the site constraints. A range of treatments should be applied to the site (treatment train approach) Design sizing of treatments, may be at a lower standard than those under the high risk descriptor if substantial cost reduction will result for a small increase in potential risk. For example, if reducing the capacity of a detention basin results in significant cost savings for a small increased sediment loss or pollution risk. Low Only low cost operational treatments to be applied. Use standard construction site management practices, comply with the DPTI Environmental Code of Practice for Construction Road Rail and Marine Facilities (DPTI, 2008) 8

9 III. Application of Targets to DPTI Projects Pollutant reduction targets for Water Sensitive Urban Design have been recommended by the South Australian Government for use in South Australia, in a policy released in November, 2013 (Department of Environment, Water and Natural Resources, 2013). Targets used by DPTI predate these, and are based on targets developed by the State Government in the 2010 Implementing Water Sensitive Urban Design (WSUD) Greater Adelaide Region project, that remain unpublished. The opportunity for retrofitting WSUD features within existing urban arterial road corridors is very limited. However, for large scale road projects, particularly in new corridors, and other projects such as the development of park and ride facilities there is scope for the inclusion of WSUD features The following targets are recommended as a starting point for individual projects: 80% reduction in average annual total suspended solids load. 45% reduction in annual average total nitrogen load. 45% reduction in average annual total phosphorus load. Retention of litter greater than 50 mm for flows up to the 3 months ARI peak flow. No visible oils for flows up to the 3 months ARI peak flow. The need for setting WSUD targets should be determined at the time a water quality risk analysis is carried out. IV. Soil Erosion and Drainage Management Plan and Water Quality Monitoring At the time of the WQRA an assessment is also made of the site erosion risk, based on a summed score of a number of influencing factors, including: Annual rainfall. Average site slope. Soil Type. Duration of risk. 9

10 Area to be disturbed at any one time. Sensitivity of receiving environment. The level of detail of the Soil Erosion and Drainage Management (SEDMP) required is based on the score. In addition the monitoring required is based on the score plus the ecosystem condition. Full details of water quality monitoring are given in the DPTI Water Quality Monitoring Manual (DPTI, 2012b). V. Application of the WQRA Procedure The WQRA procedure is very flexible in its application. It has been applied for a wide range of projects, and a wide range of project delivery methods. For a simple project it can be carried out in a single stage, with only participants from DPTI. However for a project that is delivered by design and construct a series of workshops may be required, with participation from a wide range of stakeholders, including Local Government and other State Government Departments. The use of workshops with these stakeholders results in an agreed approach to environmental management for the project. For this reason it has been found that it is critical to have the involvement of stakeholders, particularly those with a formal or legislative interest in the outcomes of the project. From the experience of many projects there are three important factors that must be taken into account: 1. When defining the risk it should be defined as an outcome. For example, the risk is not export of heavy metals from the site because this could have quite different consequences depending on the nature of the receiving environment. It would be better to define the risk as heavy metals exported from the site have a significant impact on the downstream water body, River X. It is then a much more logical exercise to assign a likelihood and consequence. 2. The post treatment risk must be assessed to enable the documentation of residual risk. This necessitated a change in the procedure. 3. It is vital that the owners of the risk are identified, and that they accept the risk. For example if a treatment is installed to manage water quality, such as a pond or wetland, it needs to be identified if DPTI or the local government agency will be responsible for the ongoing maintenance. If it is local 10

11 government their agreement to undertake on-going management of the measure needs to be obtained early in the planning phase, otherwise the treatment measure will not address the risk in the long term. To assist risk owners in accepting and managing any treatment measures, the details of the measure and maintenance regime should be documented in the Operational Environmental Management Plan or Handover document. When DPTI is identified as the risk owner, treatment measures are incorporated into the DPTI Stormwater Treatment Infrastructure Maintenance Manual (DPTI, 2012c); the DPTI Regional Stormwater Treatment Infrastructure databases and into the Maintenance contracts. The DPTI Stormwater Treatment Infrastructure Maintenance Manual is the primary tool by which the Department manages stormwater treatment measures installed as a response to risks identified through a project s WQRA process. It provides a register of the location of stormwater treatment infrastructure on the DPTI road and rail network, and the maintenance requirements to keep the facilities effective. The manual was compiled with frequent use and ability to update in mind. As new sites are installed they are included in a register. VI. Case Study McLaren Vale Overpass A. Project Overview The McLaren Vale Overpass was constructed to improve safety at the intersection by completely removing all right-angle traffic conflict from an existing on-grade intersection in a semi-rural environment near McLaren Vale, south of Adelaide, South Australia. The nature of the overpass project was a road construction/upgrade; the preferred concept was a trumpet type overpass a semi-direct on-ramp and loop off-ramp north of the overpass structure. The design was carried out internally by DPTI, with construction by contract. The project is adjacent to Pedler Creek. The Pedler Creek catchment covers an area of 101 km² with its headwaters in the Willunga escarpment of the Mount Lofty Ranges. The catchment is predominantly rural 11

12 with only the townships of McLaren Vale, and McLaren Flat and the urban suburb of Moana, located near or within the catchment. B. The WQRA Process A WQRA workshop was carried out with DPTI staff from Planning and Design, Stormwater and the Environment groups, during the design of the overpass. The project scope and delivery method meant that a simple process could be followed. All relevant external management plans and investigations were taken into account, including the local Natural Resources Management Plan, assessed environmental flow requirements, watercourse condition assessment, and the floodplain mapping that was being carried out by Council. Tables 3 and 4 below show the risk assessment tables created through the WQRA workshop, for both operational and construction phase risk assessments. 12

13 Table 3. McLaren Vale Overpass Operational Phase Risk Assessment. Risk Likelihood Consequence Risk Heavy metal export creating toxicity in downstream environment Industrial pollutants being deposited on road surface, to be later washed off. Hydrocarbons from vehicles creating significant Biological Oxygen Demand (BOD) in the downstream environment. Sediment export smothering of aquatic vegetation and something about increased turbidity and decreased light penetration. Nutrient export creating impact on water bodies Vegetative matter washed into waterways, and creating BOD Significant litter export having a visual impact Accidental Spills (including hazardous) Runoff volume change causing erosion or saturation downstream Runoff peak flow in excess of downstream pipe capacity Runoff temperature change having an impact on biota Pollutants entering groundwater Proposed Management Measures L M L N/A N/A - - N/A L M L N/A H H H Landscaping and stabilisation of drainage lines and batters, kerbing on loop to manage erosion out of a point source as opposed to across the face of the whole loop. L L L N/A M L L N/A L L L N/A L H M M M M Current stormwater design allows for reasonable distance from possible spill to entry into stormwater pipes over open ground thereby allowing time to capture and contain spillages. Treatments will be placed at discharge points into Pedlar Creek L L L N/A L L L N/A L L L N/A L = Low; M = Medium; H = High; C = Critical; N/A = Not Applicable for this location 13

14 Table 4. McLaren Vale Overpass Construction Phase Risk Assessment. Risk Likelihood Consequence Risk Proposed Management Measures Accidental spills affecting waterways L H M Detailed SEDMP required, all drainage entry points to be protected e.g. via silt socks. Pollution of waterways because of proximity of worksite Extra turbidity due to pile driving affecting water quality L L L N/A N/A - - N/A Bulk earthworks exporting sediment to deposit elsewhere in the watercourse Soil erosion that causes significant deposition in watercourses. H H H (critical) H H H Detailed SEDMP required, stabilisation of embankments, use of retention basins Soil erosion to be managed through production of a detailed SEDMP Groundwater pollution L M L N/A L = Low; M = Medium; H = High; C = Critical; N/A = Not Applicable for this location C. Outcomes of the WQRA Process The proximity of Pedler Creek was the main determinant in the treatment measures adopted. The main risks were associated with the export of sediment (both in the construction and operation phase) and accidental spills. A detailed SEDMP was thus required for the works, plus level two water quality monitoring. 14

15 Most batters and swales were immediately vegetated through hydroseeding, and then tree and shrub species during the landscaping process. An infiltration basin was constructed within the loop of the overpass to capture all runoff from the inside batters. This will allow any sediment within this water to settle. A reno mattress was placed at the end of the stormwater outlet into Pedler Creek. This helps to stabilise the area and limit erosion. The drainage strategy ensured that there was a reasonable distance from possible spill sites to entry into stormwater pipes over open ground, thereby allowing time to capture and contain spills. VII. Case Study Southern Expressway Duplication A. Project Overview In , DPTI duplicated the Southern Expressway to create a non-stop, multilane expressway with dedicated north and southbound lanes between Bedford Park and Old Noarlunga. The project corridor, which extends approximately 20 km, contains a number of watercourses and includes some areas with steep terrain. Key activities of concern included: Construction of bridges over the Sturt River, Smith Creek and Christie Creek, including scour protection works on the river banks. Diversion of the Field River in two locations (with impacts at a third location) and diversion of Trott Park Creek in one location. Extension of multi plate culverts, box culverts and cross drains under the duplicated carriageway. Modification of existing and construction of new water quality treatment basins. The scale of this project and the extent of potential risks to water quality were substantially greater than as described for the previous case study; McLaren Vale Overpass. This demonstrates how flexible the WQRA process can be when applied to different scale projects. B. The WQRA Process An initial WQRA workshop was held in April 2011 (at 5% design), involving the planning team (consultant civil and environmental engineers and DPTI environment staff) and key stakeholders (local 15

16 Council staff, EPA, Department of Environment and Natural Resources, and Natural Resources Management (NRM) Board representatives). This led to the development of the initial WQRA report. The reason for doing the risk assessment early (prior to engaging a contractor) was to establish the likely requirements for water quality monitoring and the SEDMP, and any other management/ mitigation measures that should be included in the contract (and addressed/priced by the contractor in the tender). The planning consultants coordinated this meeting and prepared the report. A subsequent internal workshop (involving staff from DPTI s environment and stormwater teams and Metropolitan region) was held in August 2011, following the release of an updated design, to ensure the findings of the initial WQRA were still applicable. After the contract had been awarded, a final workshop was held with the construction contractor, a member of the design team, DPTI staff (environment, stormwater and Metropolitan region), and key stakeholders (local Council, EPA and NRM Board). The results of this workshop (held at 30% design) were translated into an updated WQRA report produced by the contractor (DPTI, 2012d). C. Outcomes of the WQRA The WQRA identified construction phase and operational phase risks, as well as possible mitigation measures. Workshop participants ranked untreated and treated risks using the qualitative likelihood and consequence matrix provided in the DPTI Protecting Waterways Manual. An initial site erosion risk assessment was undertaken as part of the workshop, using Table 5.4 and 5.5 of the Protecting Waterways Manual (DPTI, 2012a). Based on the score, a detailed SEDMP was developed and level three water quality monitoring was required. VIII. Conclusion The Water Quality Risk Assessment (WQRA) procedure has now been in place for a number of years, and has proven to be a very worthwhile approach to determining appropriate treatments and satisfying the need to demonstrate that reasonable and practicable measures are being undertaken to minimise environmental harm. 16

17 The detail and methodology of the WQRA can be tailored to the size of the project, the project delivery method and the scale of the potential risks. The assessment for projects having significant potential impact is usually carried out in a workshop environment, with representation by a wide range of stakeholders. This results in an agreed set of treatment measures, for both the construction and operation phase. References Austroads (2001) Environmental Risk Management Guidelines and Tools for Road Projects, Publication no: AP-R Department of Environment, Water and Natural Resources (2013), Water sensitive urban design, creating more liveable and water sensitive cities in South Australia, Government of South Australia, November Department of Planning, Transport and Infrastructure (2008) Environmental Code of Practice for Construction Road Rail and Marine Facilities, Government of South Australia, April Department of Planning, Transport and Infrastructure (2012a) Protecting Waterways Manual, Government of South Australia, July Department of Planning, Transport and Infrastructure (2012b) Water Quality Monitoring Manual for Construction Sites, Government of South Australia, July Department of Planning, Transport and Infrastructure (2012c) Stormwater Treatment Infrastructure Maintenance Manual, Government of South Australia, September Department of Planning, Transport and Infrastructure (2012d) Duplication of the Southern Expressway: Water Quality Risk Assessment, Government of South Australia, April Department of Planning, Transport and Infrastructure (2013) Risk Management Policy DP086, Government of South Australia, September