Agenda of Water, Waste and Sewer Advisory Committee Meeting

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.1

Staff Reports - Infrastructure Services

Report No. 4.1 Inflow and Infiltration - Sewer Asset Management

Directorate: Infrastructure Services

Report Author: Jason Stanley, Systems Planning Officer

File No: I2019/2060

Summary:

Following a review of the 30 year capital works plan, it was identified that various gravity sewer assessments within the Mullumbimby area were scheduled for renewal over the coming years. It was agreed that condition assessments of both the gravity sewer and adjacent stormwater assets would be undertaken to verify whether these assets were in a state that warranted their renewal.

The assessments in Mullumbimby have since been completed and the findings identified that various assets are presenting a high risk to Council that should be remedied in a risk based manner. This report presents the findings of these assessments as well as identifying the proposed way forward with regards to the ongoing management of the gravity sewer and stormwater network.

RECOMMENDATION:

That Committee note the report.

Attachments:

1 Mullumbimby Catchment 4001 - Sewer Main Inflow and Infiltration Report - Willow and Sparrow, E2019/69598 , page 12⇩

2 Mullumbimby Catchment 4001 - Sewer Maintenance Hole Inflow and Infiltration Report - Willow and Sparrow.pdf, E2019/80301 , page 241⇩

3 Mullumbimby Catchment 4001 - Storm Water Main Inflow and Infiltration Report - Willow and Sparrow, E2019/71131 , page 325⇩

4 Final Stormwater MH condition assessment report.pdf, E2019/80295 , page 530⇩

REPORT

1. Introduction

This report provides a summary of the findings relating to the sewer infrastructure that is located within sewer catchment 4001 in Mullumbimby which accounts for approximately 4km of the 195km gravity sewer network. The intent of this report is to provide a summary of the findings from the condition assessment works within Mullumbimby, present the subsequent recommendations from these assessments and proposal for the ongoing management of the remainder of the sewer network.

2. Background

Inflow and Infiltration (I&I) is the process of groundwater and stormwater entering into the sewer network.

Following a review of the 30 year capital program, it was identified that 40 gravity sewer mains within the Mullumbimby catchment were proposed for renewal within the 2022-2031 horizon. This prompted some flow monitoring of the network to identify if I&I was an issue which is a high level indication of the networks condition. It was identified that I&I was evident, hence detailed investigations were undertaken to determine each individual assets overall condition and consequence of failure scores to establish the subsequent overall risk rating.

3. Scope

3.1 Location

The current scope of works for this project has focused on a small catchment of the gravity sewer network upstream of sewer pump station (SPS) 4001 within Mullumbimby including the stormwater network encompassed by the blue hatch in the below map. Mullumbimby is a low lying town that is located adjacent to the Brunswick River. This portion of the sewer catchment consists largely of Vitrified Clay (VC) pipe which is prone to brittle failure (cracking) and is therefore subject to high rates of I&I.

Figure 1 – Mullumbimby Condition Assessment Scope Extent

3.2 Condition Assessment

Following the conclusive data obtained from the flow monitoring that identified I&I as an issue for this portion of Mullumbimby’s sewage catchment, detailed assessments of both the sewage and stormwater network were undertaken. These assessments consisted of CCTV of sewer mains and stormwater culverts, visual inspections of maintenance structures, as well as smoke testing to identify potential points of entrance and incorrect stormwater connections to sewer mains.

The findings from the above assessments have all been documented in detailed condition assessment reports which can be found on HPE content manager (E2019/69598, E2019/80301, E2019/71131, and E2019/80295). These condition assessment reports provide a summary of each assets condition score. Each asset was assigned a consequence of failure based on the impact of the asset’s failure and subsequent repair/replacement which then allowed an overall risk rating to be assigned. With these risk scores being considered, capital renewal and minor rectification works have been prioritised as well as a return schedule for the future assessment of each asset.

4. Mullumbimby Assessment Findings

4.1 Overall Asset Risk

In total there were 109 sewer mains and 107 stormwater culverts that were assessed including the associated maintenance holes. It was apparent through the development of the condition assessment reports that the stormwater culverts and sewer mains that were initially constructed in the 1940s and 1960s respectively were subject to significant deterioration and had not been sufficiently maintained. Below are some images of the existing sewer mains that were assessed.

Hole in pipe wall	Defective pipe repair
Major root intrusion	Major displacement at pipe replacement
Heavy infiltration	Heavy infiltration
Hole in pipe wall	Major root intrusion

Figure 3 presents the overall risk score summary for both the sewer mains and stormwater culverts.

Figure 3 – Risk Score Summary

From Figure 3, it can be determined that 41% of the sewer network and 69% of the stormwater network within the project extent is either a high or very high risk of failure.

The risks that BSC is responsible for managing include but are not limited to the following:

a) Pipe collapse resulting in expensive emergency rectification works

b) Increased on-going sewerage operational costs due to capturing, transferring, and treating both groundwater and stormwater that infiltrates the sewer network

c) Poor conveyance of stormwater that can lead to flooding, resulting in damage to property and road infrastructure

d) Extensive infiltration into the sewer network that results in the migration of supportive material beneath road pavements which can result in the undermining of pavements resulting in their collapse (sink hole).

4.2 Proposed Rectification Works

In order to mitigate the risks that BSC is responsible for managing, a summary of the proposed renewal and minor rectification works for FY19/20 are noted in Table 1 below with the overall conceptual construction cost estimate for each asset type.

Table 1 – Proposed Rectification Works FY19/20

Asset Type	# Assets Assessed	# Assets to Rectify	Nature of Scope	Estimated Cost (±20%)
Gravity sewer main	109	26	Renewal	$400,000
Gravity sewer main	109	20	Rectification / maintenance	$40,000
Sewer MH	92	20	Rectification / maintenance	$50,000
Stormwater culvert	107*	21	Renewal	$580,000
Stormwater culvert	107*	9	Rectification / maintenance	$20,000
Stormwater MH	24	7	Rectification / maintenance	$5,000
*The assessment of only 92 stormwater mains could be completed due to obstructions			Sewer Subtotal	$490,000
			Stormwater Subtotal	$605,000
			TOTAL	$1,095,000

It should also be noted that budget for the necessary rectification of the highest priority stormwater culverts within Mullumbimby has not yet been established. A report specific to the asset management of the stormwater network is being submitted to the Transport and Infrastructure Advisory Committee (TIAC) in order to request funding.

Furthermore, in addition to the above scoped works there are various other assets within this catchment that have been assessed that can be justified for renewal over the subsequent years subject to budget availability and prioritisation against assets within other catchments.

5. Timing

The proposed sewer renewal and rectification / maintenance works have been verified and supported by Utilities officers and management and will be going to tender in December 2019 with an estimated completion before the end of FY19/20. It should be noted that this scope also includes the stormwater culvert and stormwater MH rectification / maintenance works totalling an estimated construction cost of $25,000 that will be funded by the available sewer capital budget. Therefore, the total estimated construction cost of the proposed sewer / stormwater works is $515k (excl GST).

As for the stormwater culvert renewals ($580k), budget needs to be sourced to facilitate these works prior to tendering and undertaking the construction works. A report has been presented to the Transport and Infrastructure Advisory Committee concerning the budget associated with the required stormwater rectification works as well as the ongoing management of the stormwater network.

6. Renewal Methodology

With advancements in technology and products, in some instances there are now alternative options to traditional open trench excavation “remove and replace” methods. There are various structurally integral liners that can be installed to rehabilitate pipes and culverts that are in poor condition. Fortunately, it has been identified that all of the gravity sewer mains that are proposed for rectification can be done so with a structural liner. Advantages of this methodology include:

a) Increased expediency of rectification works

b) Reduced capital expenditure (typically >50% savings)

c) Reduced community impact (traffic, noise, dust, amenity, etc.)

d) Reduced exposure to high risk works for site personnel

Depending on the type of structural liner, they can be easily removed if required without damaging the existing “host” pipe / culvert and typically have a design life of at least 50 years.

7. Budget

The existing budget for FY19/20 for the Mullumbimby sewer catchment is $590k. Spend/committed to date is $262k. Hence the remaining sewer budget is approximately $328k. An additional $200k will likely be required to facilitate these works including their management. However, this additional budget will be requested once external contractor price submissions have been received.

8. Ongoing Assessment

As the assessment of the Mullumbimby sewer and stormwater catchment has revealed the poor condition of a large portion of the catchment (41% sewer and 69% stormwater). It is evident that other portions of the BSC network may be in particularly poor condition as well. This presents various previously noted risks to BSC all of which have the potential to adversely impact on the public perception of BSC.

It is proposed in future to replicate the approach that has been adopted for this portion of the Mullumbimby catchment, and apply it to the remainder of the network in a prudent and efficient manner. However, due to a lack of funding for the stormwater network which has been highlighted in a report that is being presented to the Transport and Infrastructure Advisory Committee (TIAC), the gravity sewer main assessments in FY19/20 will have to be undertaken in isolation without stormwater.

A desktop risk analysis has been developed for the gravity sewer network based on various criteria such as age, depth, material composition, downstream peaking factors, etc. This risk analysis model enables the Asset Management team to identify the assets that are likely to be the highest risk to Byron Shire Council, and therefore the highest priority for assessment. Two of the highest risk sewer catchments in Byron Bay and Ocean Shores (3002 and 5012) totalling a length of 22.65km will be assessed in FY19/20 to gain a comprehensive understanding of their condition to enable the asset management team to manage any identified risks accordingly.

Though as previously noted, the intent is to undertake future assessments of both the sewer and stormwater infrastructure in concurrence due to the following benefits that this approach presents:

a) BSC will have accurate information to support the prudent and efficient asset management of its gravity sewer and stormwater infrastructure.

b) Cost savings due to single establishments for camera and assessment crews in addition to an increased length of CCTV assessments which will result in economies of scale.

c) A reduction in the impact to community from noise, amenity, traffic control, etc. due to the elimination of repeat works in the same areas.

It is imperative that BSC gains a comprehensive understanding of the condition of its gravity sewer and stormwater networks to ensure that their integrity and function are maintained in order to manage the associated risks accordingly.

Below is a summary of the proposed accelerated assessment program from the gravity sewer network risk analysis for the next 5 years. This accelerated program aims to compensate for the lack of assessments that have been undertaken historically. The summary in Table 2, details the lengths to be assessed and the estimated assessment cost.

Table 2 – Proposed 5 Year Works Summary

There is currently $5M available for the ongoing management of the gravity sewer network over the next 5 years inclusive of Year 1 (FY19/20). This budget has been apportioned $2.5M to the Mullumbimby catchment and $2.5M to the remainder of the sewer network. When considering the degree of urgent rectification works that were required following the Mullumbimby assessment, it is likely that the budget of $5M over 5 years will be insufficient to adequately manage the sewer network. However, the Asset Management team will have a better understanding of the budget that will be required following the completion and risk assignment of the 3002 and 5012 sewer catchments scheduled for completion in FY19/20. Following this, if required, a report will be presented to the WWSC with justification supporting an increase in the available budget.

9. Conclusion

Given the findings of the assessments that were undertaken in a relatively small portion of the Mullumbimby township, it is strongly recommended that ongoing condition assessments are undertaken for both the remainder of the gravity sewer and stormwater networks. This will provide BSC with the necessary information to manage identified risks in a prudent and efficient manner.

Furthermore, there are advantages to undertaking the assessments of these two networks in parallel. Economies of scale will dictate that an increase in value for money will be achieved in addition to other benefits such as reduced establishments and interruption to the community.

A report providing an update will be presented to the WWSC following the completion of the 3002 and 5012 gravity sewer condition assessments in FY19/20 noting whether additional budget is required to continue with the ongoing assessments and required rectification works over the five year window to FY23/24.

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.3

Report No. 4.3 Condition 9. Additional Load at Byron STP

Directorate: Infrastructure Services

Report Author: Dean Baulch, Principal Engineer, Systems Planning

File No: I2019/2155

Summary:

This report is for Council information and reviews compliance with the Byron Bay Sewerage Augmentation Scheme - Conditions of Approval (2002). Condition 9(iii) requires that sufficient reuse (recycled water) capacity be available before the acceptance of any additional load at the treatment plant.

In the years since the approval was granted (2002 to date), 2,408 Equivalent Tenements (ET) have been approved, resulting in an additional load of 1.42ML/day at the treatment plant. The current day operating capacity of the reuse system equates to 2.02ML/day or 3,427ET. Therefore the reuse system provides sufficient capacity to accommodate the additional load as defined in the Conditions of Approval

This report is a response to resolution 540 point 5, 6 and 19-598 point 2 and 3.

RECOMMENDATION:

That Council:-

1. Note that compliance with Condition 9 of the Approval is satisfactory.

2. That staff investigate and recommend a modern day industry method for calculating Average Dry Weather Flow that can be applied consistently across all of Council’s Sewage Treatment Plants.

Attachments:

1 Byron Bay Sewerage Augmentation Scheme - Conditions of Approval, DM387682 , page 753 ⇩

2 ASSESSING THE DEMANDS & SUPPLY CAPACITY OF THE BYRON BAY URBAN RECYCLED WATER SCHEME - Planit Consulting 2018, E2019/93964 , page 763 ⇩

REPORT

19 - 540

Resolved that Council adopt the following Committee Recommendation(s):

Report No. 4.2 Byron Bay Integrated Management Reserve Update

File No: I2019/1588

Committee Recommendation

1. (…)

5. That listing for Byron Bay STP Catchment of sewage load resulting from Development Consents after 9 December 2002 (or similar) be brought to the next WWSAC.

6. That Council note that Byron Bay STP capacity was reassessed in recent years.

7. That Council note that when ADWF reaches 80% of plant capacity (assessed in 2002 as 6.95 ML/day) Condition 6 requires action by Council.

19 - 598

Resolved that Council adopt the following Committee and Management Recommendation(s):

Report No. 4.1 Byron Bay Integrated Management Reserve - Byron Bay STP Catchment

File No: I2019/1847

Committee Recommendation 4.1.1

1. That the Council note the report.

2. That a report on Byron Bay STP Catchment sewerage load resulting from Development consents after 9 December 2002 (or similar) be brought to the next meeting of WWSAC.

3. That the Conditions of Consent for the Byron Bay STP be included with the Report.

In 2002 the Byron Sewage Augmentation Scheme was approved. This scheme comprised of the upgrading of West Byron Sewage Treatment Plant (STP), decommissioning of South Byron STP, construction of a sewerage transfer pipeline between South Byron STP and West Byron STP, and upgrading of associated pumping stations.

Byron Sewerage Augmentation Scheme was put to a special meeting of Council, held at Council’s chambers on 9 December 2002. The resolution (02–1329) of Byron Shire Council adopted the Conditions of Approval (see Attachment 1) for the Scheme.

The Waste and Water Sewage Advisory Committee recently requested information regarding Council’s compliance with the consent conditions of the report. The Committee’s request was specifically related to Condition 9 of the resolution. This report also expands into other related parts of the “Conditions of Consent”.

The section from Condition 9 of the Approval that has raised the query is Condition 9(iii), which states, “Additional load at West Byron STP will not be accepted until: availability of sufficient reuse capacity to accommodate 100% of the volume of treated effluent generated by the additional load”.

“Additional Load” is defined in the report as “any sewage load resulting from development consents after the date of this approval”. Date of Approval is 9 December 2002.

From December 2002 to the end of November 2019, 2,408 additional sewer Equivalent Tenements (ET) have been approved by Council through development consents.

The theoretical capacity of the effluent reuse system is 1.77 ML/d (3,000ET). This was modelled by Planit Consulting in 2018 (see Attachment 2). The current day operating capacity of the reuse system to produce treated effluent is 26 Litres per second or 2.25ML/day less 10% of water for filter backwash purposes equates to 2.02ML/day or 3,427ET. Therefore the reuse system provides sufficient capacity to accommodate the additional load as defined above.

As stated the current operational capacity of the effluent reuse system is 2.02ML/day (January 2020). This is planned to be increased to 2.77ML/day (4,695ET) in the current financial year by carrying out pipework modifications and upgrades at the plant.

Summary	Current ET	Available Capacity (ET)
Condition 9(iii) Additional Load Calculation	2,408	-
Theoretical effluent reuse system capacity 2018	3,000	592
Current effluent reuse system capacity 2020	3,427	1,019
Future effluent reuse system capacity >2021	4,695	2,287

It is important to note the difference between actual use of the reuse system and the capacity of the system. Actual use is dependent on environmental conditions – factoring in rainfall and drought. The number of users is the other large factor in taking up the reuse effluent volume - more customers obviously increases demand and consumption. The following graph shows the actual reused volume used against the additional load.

The current Byron Shire Recycled Water Management Strategy 2017 – 2027, adopted by Council, sets out the strategic direction for recycled water management in the Byron Shire. In order to meet the key direction targets of the Strategy as well as Condition 9(iii), various infrastructure projects are required to be constructed. Included in the Strategy is development of the rural and environmental scheme along the Western Corridor. Council is currently investigating the supply options to the Western and Southern Corridors. Potential customers identified to the west include “The Farm”, “Sea Peace”, Cape Nursery and several macadamia farmers. Along the Southern Corridor there are a number of macadamia farmers who have requested connection to the scheme. The supply to each customer will be assessed on its merits (cost/benefit analysis).

The first customer identified for connection to the scheme along the Western Corridor is “The Farm” due to the close proximity to existing infrastructure. This customer is expected to be connected early in the 2020/2021 financial year. The supply to the Western and Southern Corridors will meet the Strategy’s planned focus to be of beneficial use in rural and environmental applications.

Condition 6 of the “Conditions of Approval” also states that when the ADWF reaches 80% of treatment capacity, investigations must commence to identify feasible strategies for the management of sewage flows above the capacity of the plant. Following the flow trends from 2002 to current (27 November 2019), the plants 80% capacity is expected to be reached in 2025. Council staff will continue to monitor the inflows into the plant and once 80% capacity is reached, will commence investigation of strategies for management of sewage flows.

The following graph shows the flow trend for the Byron STP. The data points above and below the linear trend are an indication of wetter or dryer than average years. The current drought conditions being experienced are evident in the 2019 flow data values.

The actual ADWF figures are an average of the full years flow totalised daily at the Byron STP. The top 20% and bottom 10% of data was removed from the calculations to exclude rainfall effect and recording anomalies from the figures used. The result is the annual ADWF. Within Byron Bay the ADWF varies according to the season. There is a summer peak in Dec/Jan and over Easter; a winter low and the "shoulder period" during the remaining time. This creates a range that is not reflected in the graph or data. The actual flow reflected is an average of the year’s data.

The data shows that the actual and derived (through ET calculations) ADWF trends over the past 15 years are tracking parallel to each other, indicating a level of certainty with the figures used. Based on the last 15 years of actual flow data, the Byron STP is expected to reach capacity in 2042.

The method stipulated in the “Conditions of Approval” states the definition for ADWF as “the average flow over a period of not less than five (5) consecutive days with no rainfall, with no more than 5mm of rain in the preceding ten (10) days”. Using this method, there is the potential to obtain skewed results due to the large flow variations over the three flow periods. ADWF in the winter can be as low as 60% of the summer peak. In order to ensure the actual annual average was calculated, the entire year’s data has been used.

On 22 March 2018 Council Resolution 18-193 adopted the Policy - Water and Sewer Equivalent Tenements 2018 that includes the Dry Weather Flow definition:

The average daily flow to the treatment works during seven consecutive days without rain (excluding a period which includes public holidays) following seven days during which the rainfall did not exceed 0.25 millimetres on any one day.

The above highlights that we have varying definitions for calculating ADWF and we now have an opportunity to update this calculation/condition in line with modern day industry methods that can also be applied consistently across all of Council’s treatment plants.

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.3 - Attachment 1

Byron Bay Sewerage Augmentation Scheme – Conditions of Approval

General

1. The proposal shall be carried out in accordance with:

(i) the proposal contained in the EIS and SIS Byron Bay Sewerage Augmentation Scheme dated 30 August 2001 prepared for Byron Shire Council by Environmental Resources Management Australia Pty Ltd, subject to modifications to the proposal as described in the document Byron Bay Sewerage Augmentation Representations Report (the Representations Report) prepared for Byron Shire Council by Environmental Resources Management Australia Pty Ltd dated September 2002;

(ii) all identified procedures, safeguards and mitigation measures identified in the EIS, SIS, and Representations Report;

(iii) the conditions of concurrence imposed by the Director–General of the NPWS in the document Concurrence Report for the Proposed Establishment of a 24 ha Melaleuca Regeneration Area, West Byron Sewage Treatment Plant dated June 2002 prepared by NPWS Conservation Programs and Planning Division–Northern Directorate; and

(iv) the conditions of approval imposed by Byron Shire Council.

In the event of any inconsistency between the conditions imposed by Council (these conditions) and recommendations contained in the EIS, SIS or Representations Report, these conditions shall prevail.

Notwithstanding the above, in the event of any inconsistency between the concurrence conditions imposed by the Director–General of the NPWS and these conditions, the recommendations in the EIS, SIS, or Representations Report, the concurrence conditions imposed by the Director–General of the NPWS shall prevail.

These conditions do not relieve Council of the obligation to obtain all other necessary approvals, licences or permits required under any other Act. Without affecting the generality of the foregoing, Council shall comply with the terms and conditions of such approvals, licences and permits.

Finalisation of draft Byron Bay Effluent Management Strategy

2. Council shall, as soon as practicable but no later than six (6) months from the date of this approval, finalise the draft Byron Bay Effluent Management Strategy. As part of finalisation of the draft strategy, Council shall:

· consult with the EPA, and take into account any comments it may have with regard to the implementation of the strategy; and

· include provision for the periodic review of the strategy, this period to be no greater than five (5) years.

Definitions

3. For the purposes of implementation of these approval conditions, the following definition of ‘Average Dry Weather Flow’ (ADWF) shall apply:

‘The average flow over a period of not less than five (5) consecutive days with no rainfall, with no more than 5 mm of rain in the preceding ten (10) days.’

The efficacy of this definition shall be reviewed no later than 12 months from the date of commissioning of the West Byron STP augmentation and at 12 month intervals thereafter. The review shall include consultation with relevant stakeholders, including, but not limited to: DLWC, the Byron Bay Wastewater Steering Committee. If deemed appropriate, this definition may be amended, subject to a process including consultation with relevant stakeholders.

4. For the purposes of implementation of these approval conditions, the following definition of ‘additional load’ shall apply:

‘Additional load is any sewage load resulting from development consents after the date of this approval.

5. For the purposes of implementation of these approval conditions, the following definition of ‘reuse project’ shall apply:

‘An enterprise utilising treated effluent under a valid Environment Protection Licence where required, holding a valid contract with Council, and with all required infrastructure in place and operational.

West Byron STP Capacity

6. West Byron STP shall not accept flows for treatment in excess of 6.95 ML/day (ADWF). This is the plant’s treatment capacity. Council shall continuously monitor the Average Dry Weather Flow entering the upgraded West Byron STP to assess the load on the plant in relation to the plant’s treatment capacity. When 80% treatment capacity is reached, Council shall investigate feasible strategies for management of sewage flows above the capacity of the plant. In the event that load exceeds 100% treatment capacity, Council shall meet to discuss appropriate courses of action to prevent further exceedances.

7. The load which shall be received at West Byron STP at the time of commissioning of the upgraded plant shall be limited to the load from the West Byron catchment at that time.

8. The transfer of sewage flows from South Byron STP to West Byron STP catchment shall be conditional upon:

(i) West Byron STP satisfactorily meeting all applicable performance requirements as per construction contract requirements and as specified in the plant’s Environment Protection Licence and in this approval; and

(ii) the availability of a reuse project(s) capable of accepting a minimum of 326 ML/yr of treated effluent as determined in the Effluent Management Strategy.

9. Additional load at West Byron STP will not be accepted until:

(i) the transfer of 100% of the sewage flows from South Byron catchment;

(ii) West Byron STP satisfactorily meeting all applicable performance requirements as specified in the plant’s Environment Protection Licence and in this approval;

(i) availability of sufficient reuse capacity to accommodate 100% of the volume of treated effluent generated by the additional load; and

(iv) availability of treatment capacity as defined in Approval Condition 6 above.

Effluent Quality Standard for West Byron STP

10. Unless otherwise determined by the EPA, treated effluent produced by West Byron STP, as measured at the licensed STP outlet (unless otherwise indicated), shall meet the following quality standards:

Parameter	Abbreviation	Units	Standard (90^th percentile)
Biochemical Oxygen Demand	BOD₅	mg/L	10
Suspended solids	SS	mg/L	15
Total Nitrogen	TN	mg/L	3 (50^th %ile)
Total Phosphorus	TP	mg/L	0.5 / 0.3¹
Faecal Coliforms	FC	cfu/100 mL	200

¹ At the licensed STP outlet and wetland outlet respectively

The quality of treated effluent delivered to reuse sites shall be subject to separate determination.

Nutrient Load Limit for West Byron STP

11. Nutrient loads discharged to Belongil Creek, as measured at the outlet of the constructed wetland, shall not exceed 1,502 kg per year for Total Nitrogen and 300 kg per year for Total Phosphorus.

. Council shall continuously monitor nutrient loads discharged to the Belongil Creek. Determination of nutrient loads shall be based on a minimum of weekly sampling continuously averaged over a two month period, converted to an equivalent annual load.

In the event that the equivalent annual nutrient load for either Total Nitrogen or Total Phosphorus exceeds 80% of the applicable limits specified in this Approval Condition, Council shall investigate feasible management strategies to reduce loads below 80%.

In the event that the equivalent annual nutrient load for either Total Nitrogen or Total Phosphorus exceeds 100% of the applicable limits specified in this Approval Condition, Council shall meet to discuss appropriate courses of action to prevent further exceedances.

Byron Bay Wastewater Steering Committee

12. The Byron Bay Wastewater Steering Committee shall be consulted with respect to all matters relating to wastewater management (including reuse) for Byron Bay. Council shall review the need for the Byron Bay Wastewater Steering Committee upon commissioning of the West Byron STP and adoption of the Byron Bay Effluent Management Strategy.

Construction Environmental Management Plan

13. Prior to the commencement of construction works, Council shall prepare a Construction Environmental Management Plan (CEMP). The plan shall be prepared in consultation with the EPA, NPWS, DLWC, the Byron Bay Wastewater Steering Committee, and any other relevant party. The plan shall also be prepared in accordance with these conditions of approval, all relevant Acts and Regulations, and accepted environmental management best practice.

14. The CEMP shall address, but not be limited to, the following:

(i) specific environmental management objectives and strategies for the main environmental management elements and include, but not be limited to: water quality; noise and vibration; air quality/odours; erosion and sedimentation; access and traffic; property acquisition and/or adjustments; heritage and archaeology; groundwater; contamination; waste/resource management; flora and fauna; weed control; acid sulphate soils, hydrology and flooding; geotechnical issues; visual screening, landscaping and rehabilitation; hazards and risks; energy use, resource use and recycling; and utilities;

(ii) identification of the statutory and other obligations which Council is required to fulfil during project construction including all approvals and consultations/agreements required from authorities and other stakeholders, and key legislation and policies which control the Proponent’s construction of the project;

(iii) definition of the role, responsibility, authority, accountability and reporting of personnel relevant to the EMP;

(iv) measures to avoid and/or control the occurrence of environmental impacts;

(v) measures (where practicable and cost effective) to provide positive environmental offsets to unavoidable environmental impacts;

(vi) environmental management procedures for all construction processes which are important for the quality of the environment in respect of permanent and/or temporary works;

(vii) monitoring, inspection, and test plans for activities and environmental qualities which are important to the environmental management of the project including performance criteria, specific tests, protocols (eg frequency and location) and procedures to follow;

(viii) steps Council intends to take to ensure that all plans and procedures are being complied with; and

(ix) consultation requirements with relevant government agencies.

15. The CEMP shall be made publicly available.

Community Notification

16. Throughout the construction phase, Council shall keep the local community informed of the progress of the project including any traffic disruptions and controls, construction of temporary detours, changes to local access and any work required outside normal construction hours.

17. At least one week prior to commencement of construction of the transfer pipeline, Council shall provide written information to affected residents of properties adjoining the pipeline route regarding the timing and duration of the works.

Contact Telephone Number and Complaints Register

18. Prior to the commencement of construction works, Council shall establish and publicly advertise a contact telephone number to operate for the duration of the construction period, to allow any member of the public to make a complaint or comment about the construction works. The contact telephone number shall be staffed during normal business hours. An initial response to any complaints received shall be provided within 2 (two) working days and, where required, a more detailed response within 10 (ten) working days.

19. Council shall establish a complaints register to record details of any complaints received.

Construction Contractor’s Environmental Management Responsibilities

20. Construction tenders must include suitable documentation of accreditation in accordance with the Construction Policy Steering Committee’s Environmental Management Systems Guidelines.

21. In the assessment of tenders for construction of the proposal, Council shall include as a key evaluation criterion, the tenderer’s demonstrated commitment to environmental management and track record in this regard.

22. Council shall require that the successful contractor includes as part of its project team, an environmental adviser with appropriate qualifications in environmental management and/or environmental auditing. Council shall define the role of the environmental adviser in the contract documentation for the project and the role shall include undertaking regular environmental compliance audits, providing training in environmental issues for the contractor’s personnel and overseeing implementation of contractor’s environmental management responsibilities.

Construction Stage Environmental Audit

23. On at least one occasion, at a time approximately midway through the construction period, Council shall engage an appropriately qualified and experienced environmental auditor to conduct an audit of the construction activities with respect to compliance with these conditions of approval, the measures contained in the EIS and the requirements of any other licences or approvals. Where required, the audit shall include recommendations to address any identified non–compliances.

Construction Hours

24. All construction activities shall be undertaken between 7.00 am to 6.00 pm Monday to Friday, 8.00 am to 1.00 pm Saturdays with no work on Sundays or Public Holidays except for construction work which fulfils the following:

(i) any works which do not cause noise emissions to be audible at any nearby residential property;

(ii) the delivery of materials which is required outside these hours requested by the police or other authorities for safety reasons; or

(iii) emergency work to avoid the loss of lives and/or property, and/or to prevent environmental harm.

Construction Noise

25. Council shall prepare a Noise Management Plan for inclusion in the CEMP which will identify practical and cost–effective noise abatement measures to be implemented with the objective of meeting the following construction noise level criteria:

(i) for construction periods of four weeks or less, the L₁₀ noise level, when measured over a period of not less than 15 minutes when the construction site is in operation, must not exceed the background level by more than 20 dB(A);

(ii) for construction periods of greater than four weeks and not exceeding 26 weeks, the L₁₀ level, measured over a period of not less than 15 minutes when the construction site is in operation, must not exceed the background level by more than 10 dB(A); and

(iii) for construction periods greater than 26 weeks, the L₁₀ level, measured over a period of not less than 15 minutes when the construction site is in operation, must not exceed the existing background noise level by more than 5 dB(A).

A value of 5 dB(A) shall be added to the sound pressure levels recorded from the construction activities if the noise is substantially tonal or impulsive in character.

Erosion and Sedimentation Control

26. As part of the CEMP, Council shall prepare a detailed Erosion and Sedimentation Control Plan which details principles and measures to be implemented during construction including the following:

(i) installation of erosion and sediment control structures around stockpiles and downslope of excavation areas;

(ii) minimisation of cleared areas; and

(iii) ongoing revegetation of disturbed areas.

The Plan shall be prepared in consultation with the EPA and DLWC

27. As part of the CEMP, Council shall develop, in consultation with the EPA, a water quality monitoring program and incident response procedure to detect and manage any incidences of pollution of waterways by effluent during construction.

Air Quality

28. During construction, Council shall implement dust suppression measures on unsealed roads and on spoil stockpiles to minimise dust generation.

Landscape and Rehabilitation

29. As part of the CEMP, Council shall prepare a landscape plan detailing landscaping and revegetation works to be undertaken at the West Byron STP site, the South Byron STP site and along the transfer pipeline route.

Traffic Management

30. As part of the CEMP, Council shall prepare a Traffic Management Plan detailing measures to be implemented to minimise disruption to traffic during the construction of the transfer pipeline. The Procedure shall include a protocol for notifying properties adjoining the pipeline route of the construction works. The Plan shall include, but not be limited to, consideration of the following management measures:

(i) need for road closures and detours;

(ii) temporary reduction of lane widths on Ewingsdale Road;

(iii) reduced construction speed zone limit; and

(iv) locations for safe parking of construction vehicles.

Indigenous Heritage

31. Council shall ensure that a qualified archaeologist is present during ground–disturbing construction works in Survey Units 2 and 4 and during initial planting works in Survey Unit 5. If any potential sites or artefacts of indigenous heritage significance are identified, work in the immediate area shall cease and the NPWS, Arakwal Aboriginal Corporation, and Byron Shire Council Aboriginal Consultative Committee consulted to determine the most appropriate course of action.

32. The Arakwal Aboriginal Corporation shall be invited to undertake monitoring during construction activities in areas of potential cultural heritage sensitivity.

33. As part of the induction and training program for personnel involved in the project construction, the requirements of the National Parks and Wildlife Act 1974 in relation to indigenous heritage shall be addressed.

34. If any construction work is undertaken on land subject to a Native Title Claim, a process of consultation must be undertaken with the relevant claimant group.

Non-indigenous Heritage

35. During construction works, an exclusion zone of at least 10 m radius is to be established around the Byron Bay Railway Station and Stationmaster’s Residence, and the Railway Water Tower. No construction work shall be undertaken within this exclusion zone.

36. Council shall consult with the NSW Heritage Office to develop a suitable research design to undertake an archaeological assessment of the pipeline route through the identified area. The assessment shall be undertaken prior to the commencement of construction and an excavation permit under the provisions of the Heritage Act 1977 obtained if required.

Waste Management

37. As part of the CEMP, Council shall prepare a Waste Management Plan to address the management of wastes during construction works. The Plan shall identify requirements for waste avoidance, reduction, reuse and recycling. It shall also detail requirements for handling, stockpiling and disposal of wastes specifically spoil, contaminated soil or water, demolition material, cleared vegetation, oils, greases, lubricants, sanitary wastes, timber, glass, metal, etc. It shall also identify any site for final disposal of any material. Any waste material that is unable to be reused, reprocessed or recycled shall be disposed of to a landfill licensed by the EPA to receive that type of waste.

Commissioning of Upgraded West Byron STP

38. The construction EMP shall include specific risk management measures to minimise the likelihood of disruption to operation of West Byron STP during connection of new infrastructure.

39. The construction EMP shall also identify appropriate contingency measures for implementation in the event that problems are encountered with connection of the new infrastructure.

40. The EPA shall be consulted with respect to the development of the above mentioned risk management and contingency measures.

Operational Environmental Management Plan

41. Council shall formally adopt an Operational Environmental Management Plan (OEMP) for the upgraded West Byron STP no later than one month prior to the commissioning of the plant. The plan shall be prepared in consultation with the EPA, NPWS, DLWC, BBWSC, the Belongil Swamp Private Drainage Board and any other relevant stakeholder. The plan shall be prepared in accordance with these conditions of approval, all relevant Acts and Regulations and accepted environmental management best practice.

42. The OEMP shall address, but not be limited to, the following:

(i) identification of the statutory and other obligations which Council is required to fulfil including all licences/approvals and consultations/agreements required from authorities and other stakeholders, and key legislation and policies which control Council’s operation of West Byron STP;

(ii) ongoing consultation with all relevant stakeholders;

(iii) details of a monitoring program to be implemented including sampling strategies and protocols to ensure the quality of the monitoring program;

(iv) steps Council intends to take to ensure that all plans and procedures are being complied with;

(v) relevant provisions of the Belongil Estuary Management Plan; and

(vi) management strategies employed for: effluent reuse options; effluent management including monitoring at discharge points in terms of quality and quantity, groundwater levels; groundwater quality monitoring; biosolids disposal; noise; water quality; air quality (including dust and odours); health and public safety; landscaping and maintenance and issues relating to flora and fauna; security; waste/resource minimisation, management, removal and disposal; hydrology and flooding; hazards and risks, and emergency response plans; energy use and measures for minimisation.

43. The OEMP shall be made publicly available.

44. A suitably qualified and experienced consultant shall be engaged to provide advice on the inherent uncertainties associated with the results generated by the computer simulation model(s) used in the environmental assessment. Relevant information regarding this uncertainty shall be addressed in preparation of the operational EMP. The findings of the investigation shall be made publicly available.

Monitoring

45. As part of the OEMP, Council shall, in consultation with relevant stakeholders, prepare and implement a Monitoring and Impact Verification Plan (MIVP). The MIVP shall be prepared within three (3) months of commissioning of the augmented West Byron STP and shall address all applicable matters as identified in the EIS, SIS, NPWS Concurrence Report, Representations Report and any other relevant documents.

Monitoring activities which do not fall under a specific licence, permit or other form of approval shall be reviewed annually and amended as appropriate. The review process shall also include consultation with appropriate State government agencies and other relevant stakeholders.

The results of all monitoring and assessments of impact prediction accuracy shall be incorporated into the annual report detailing the performance of the sewerage system.

Decommissioning of South Byron STP

46. Subject to the satisfactory performance of the augmented West Byron STP in accordance with all applicable licence and approval conditions, the decommissioning of the South Byron STP site, as described in the EIS, shall be completed within twelve (12) months of the permanent transfer of South Byron STP sewage catchment flows to West Byron STP.

47. Council shall ensure the Environment Protection Licence for South Byron STP is retained until such time it has been adequately demonstrated that West Byron STP is operating in accordance with applicable performance requirements as specified in the West Byron STP Environment Protection Licence and in this approval.

Operation Stage Environmental Audit

48. Twelve (12) months following handover of the upgraded plant by the construction contractor, Council shall engage an appropriately qualified and experienced environmental auditor to conduct an audit of the plant’s operation with respect to compliance with these conditions of approval, the measures contained in the EIS and the requirements of any other licences or approvals. Where required, the audit shall include recommendations to address any identified non–compliances. The findings of the audit shall be made publicly available.

Sewerage System Performance Reporting

49. Council shall prepare an annual report detailing the performance of the sewerage system with respect to all performance objectives specified in all applicable licences and approvals. For the second and subsequent years of operation of West Byron STP, the report shall include comparisons with preceding years. The report shall be made publicly available at no cost to interested parties.

Constructed Wetland Performance

50. Commissioning of the augmented West Byron STP shall be conditional upon completion of all required works associated with establishment of the constructed wetland at least 12 months prior to commissioning.

51. Prior to commissioning of the upgraded wetland, suitable criteria shall be developed to provide an objective measure of the success or otherwise of the upgraded wetland and its readiness for incorporation into the STP process train.

Water Quality

52. Prior to the commissioning of the project and as part of the OEMP, Council shall prepare, to the satisfaction of the EPA, a detailed operation stage Water Quality Monitoring Program which shall address, but not be limited to, the following:

(i) water quality monitoring locations, including locations upstream and downstream of the wetland system;

(ii) frequency of sampling;

(iii) testing and verification protocols;

(iv) reporting mechanisms; and

(v) actions to be undertaken if non–compliance with specified water quality parameters is identified.

53. Notwithstanding item (v) in Approval Condition 52, in the event that the performance of the augmented West Byron STP does not meet the limits of the EPA Environment Protection Licence for three (3) consecutive months, Council shall suspend acceptance of any additional load until satisfactory resolution of the issues contributing to the non–compliances. Additional loads shall only be accepted following satisfactory compliance with the specified water quality parameters for a period of three (3) consecutive months from the date of resolution.

54. As part of the OEMP, Council shall, in consultation with the EPA, develop a monitoring and verification protocol to verify the predicted benefits to water quality in Tallow Creek as a result of the project.

Acid Sulphate Soils

55. As part of the OEMP, Council shall prepare an Acid Sulphate Soils (ASS) Management Plan outlining measures to identify areas of ASS and management measures to be implemented. The Plan shall be prepared in accordance with the Acid Sulfate Soils Manual (ASSMAC, 1998) and any subsequent revisions.

Groundwater

56. As part of the OEMP, Council shall consult with the DLWC with regard to the most suitable locations for regional bores for the timely detection of off–site waterlogging. Council shall also consult with the DLWC regarding technical details for the configuration of additional groundwater monitoring bores.

Drainage Management Plan

57. As part of the OEMP, Council shall, in consultation with the Belongil Swamp Private Drainage Board, develop and implement a Drainage Management Plan which shall address, but not be limited to:

(i) drainage charges;

(ii) flow and water quality monitoring;

(iii) access and drain maintenance; and

(iv) erosion control.

58. Council shall enter into negotiations with the Belongil Swamp Private Drainage Board regarding contributing (financially and/or as otherwise agreed) toward the maintenance of the Board’s drains used by Council for the conveyance of treated effluent to Belongil Creek. As far as practicable, negotiations shall be finalised prior to the commissioning of the augmented West Byron STP.

Flora and Fauna

59. Council shall investigate the specific habitat requirements of the Comb–crested Jacana (Irediparra gallinacea) with respect to the species’ minimum water depth requirements and incorporate this into the operating strategy for Cell H. This investigation shall be completed prior to commissioning of the upgraded West Byron STP.

Odour Management

60. As part of the OEMP, Council shall prepare an Odour Complaint Response Procedure which outlines the actions to be undertaken, including monitoring, if a complaint is received in relation to odour levels in the vicinity of West Byron STP or the transfer pipeline.

Review/Reporting Periods

61. Unless otherwise stated, the timing of all annual reviews and reporting shall coincide with any similar review/reporting required under the plant’s Environment Protection Licence.

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.4

Report No. 4.4 Byron Bay Integrated Water Management Reserve

Directorate: Infrastructure Services

Report Author: Bryan Green, Water Sewer Systems Environment Officer

File No: I2020/53

Summary:

This report is in response to questions raised by the Waste and Water Sewage Advisory Committee, and subsequent recommendation 19-540 and 19-597 that a report be submitted to Council an update whether Byron Bay Wetland Cells are lined (or not), report on information provided by State authorities and Historical Society regarding the existence and whereabouts of the Sand Mine Drain in the vicinity of the Byron STP.

RECOMMENDATION:

That Council note the report

Attachments:

1 West Byron Sewerage Treatment Plant Wetlands - Cell J Infiltration Trial.tr5, DM515792 , page 789 ⇩

REPORT

The following questions were required to be answered from Council Resolution 19-540. These questions address Council Resolution 19-597:

19 - 540

Resolved that Council adopt the following Committee Recommendation(s):

Report No. 4.2 Byron Bay Integrated Management Reserve Update

File No: I2019/1588

Committee Recommendation

1. That Council note the report

2. That Council acknowledge that Wetland cells at Byron Bay STP are lined as follows:

a) Cells D, E, and I are lined;

b) Cell H behaves as if its lined; and

c) F and G are not lined

3. That Council contact relevant state authorities and Byron Bay Historical Society to search their archive for reports on the Sand mining activities around Byron Bay and Suffolk Park and especially near Byron Bay STP

4. When this information has been assembled, Council consider a site visit for committee members.

5. That listing for Byron Bay STP Catchment of sewage load resulting from Development Consents after 9 December 2002 (or similar) be brought to the next WWSAC.

6. That Council note that Byron Bay STP capacity was reassessed in recent years.

7. That Council note that when ADWF reaches 80% of plant capacity (assessed in 2002 as 6.95 ML/day) Condition 6 requires action by Council.

19 - 597

Resolved that Council adopt the following Committee Recommendation(s):

Report No. 14.3 Report of the Water, Waste and Sewer Advisory Committee Meeting held on 14 November 2019

File No: I2019/1588

Committee Recommendation

1. That Council note the minutes of the Water, Waste and Sewer Advisory Committee Meeting held on 14 November 2019.

2. That Council adopt the previous minutes and that the item be put in the next Agenda clarifying the sentence at 4.2 about the behaviour of Wetlands cells H and J.

Res 19-540 point 1: That Council note the report

Noted – no action required.

Res 19-540 point 2: That Council acknowledge that Wetland cells at Byron Bay STP are lined as follows:

a) Cells D, E, and I are lined;

b) Cell H behaves as if its lined; and

c) F and G are not lined

And Res 19-597 point 2: (…) the item be put in the next Agenda clarifying the sentence at 4.2 about the behaviour of Wetlands cells H and J.

Staff Response: According to the Byron Wetlands Construction Site Engineer, during the 2004-05 construction period:

· Cells E, I and J are lined with a clay liner; unfortunately no works-as-executed records are available for this work.

· These cells were excavated down to indurated sand, bund walls raised from the indurated sand, sealed with clay lining.

· Due to budget constraints, Cell D was lined with mixture of compacted imported fill.

· Research conducted shows Cell H could not be identified whether the Cell is lined or has not been lined. However, it must be noted that during the 10 years of observation Cell H has shown characteristics and behaviours that the cell has been lined with organic materials. This suggests evaporation appears to be the only mechanism evident thereby limiting impact to groundwater, levels and quality. .

Cell G and F were existing cells with community committees nominating retaining these cells as habitat / treatment cells.

No records to date have been found to identify if these two cells were lined or not.

The Site Engineer’s reporting may be in disagreement with other sources to claim the wetland cells are not lined; however, this could be attributed to a difference in terminology and understandings of what lining technique of lining was used.

According to the report West Byron Sewerage Treatment Plant Wetlands – Cell J Infiltration Trial (DM515792), Cell J showed evidence of leakage and percolation of up to 2 mm/day. However, evidence from other similar ecosystems showed that over a number of years benthic material such as suspended solids, detritus and other materials sealed of wetlands, thereby creating a natural liner. To further support this theory, during Council’s operational maintenance of the Cells, the lengthy drying times suggest that evaporation is the only mechanism at play.

Res 19-540 point 3:

That Council contact relevant State authorities and Byron Bay Historical Society to search their archive for reports on the Sand mining activities around Byron Bay and Suffolk Park and especially near Byron Bay STP.

Staff Response: The response from NSW Minerals Council, which is the leading industry association representing the state’s minerals industry (http://www.nswmining.com.au/) claimed they have no knowledge of a sand mine drain in the area and Council contact Norm Graham, NPWS. Council Staff has submitted this report to the committee at previous meetings.

Further, Council is waiting on a response from the Historical Society.

The documents tabled include:

· The EIS surface and groundwater conceptual and numerical models of the Byron Bay STP area and surroundings.

· Specific studies of proposals for remediation of the Sand Mine Drain upstream from the Byron Bay STP area.

· A geology and geomorphology Study combine with a historical study of the mineral sand mining activities in the Byron Bay area.

· The 2009 Belongil Creek Flood Study.

· The 2015 Belongil Creek Floodplain Risk Management Study and Plan.

· Technical Memorandum - Sandmining drain/track status and impact on Belongil catchment

The table below shows information recently collated in relation to the Sand Mine Drain.

Document Location	Date	Document title	Author	Relevant information
E2020/3308	2001-05-01	West Byron Bay Sewerage Treatment Plant - Effluent Management Study, Phase 2	PPK Environment & Infrastructure Pty Ltd. A Parsons Brinckerhoff Company	Surface and Ground Water information of the BBSTP The 2001 EIS information was based on this report
E2016/73776	2001-08-30	Byron Bay Sewerage Augmentation Scheme - Environmental Impact Statement for NSW Department of Land and Water Conservation and Byron Shire Council - Volume Two	Environmental Resources Management Australia Pty.	Subchapter 9.2.2 Drainage Network - Belongil Catchment
E2016/73776	2001-08-30	Byron Bay Sewerage Augmentation Scheme - Environmental Impact Statement for NSW Department of Land and Water Conservation and Byron Shire Council - Volume Two	Environmental Resources Management Australia Pty.	Groundwater boreholes in relevant areas for this investigation, Groundwater model, impacts and conclusions
E2020/3310	2003-10-09	Proposal to Reduce Groundwater Flow from the Sandmine Drain near Byron Bay		Complete study of the drain, including Remediation Options, etc
E2020/3298	2004-05-03	The Geology and Geomorphology of The Cape Byron Headland Reserve and The History of Mineral Sand Mining in the Byron Bay Area	Cape Byron Headland Reserve / Southern Cross University	Information of the area and the mining activity related including historical documentation
E2020/3299	2006-03-01	Tyagarah Drain Remediation Trial Project - Concept Design - Draft	Prepared by David Pont (Southern Cross University) for the NSW Department of Environment and Conservation (NPWS) and Byron Shire Council as a community service	Complete study of the drain, including Remediation Options, Ecology, Hydrology, Hydraulics, etc.
E2018/22152	2009-11-12	Belongil Creek Flood Study	SMEC AUSTRALIA PTY LTD	The Belongil Creek Flood Study constitutes the first stage of the management process for the Belongil Creek catchment. It has been prepared for Byron Shire Council by SMEC Australia Pty Ltd to define flood behaviour under current conditions. The study has been completed in accordance with the NSW Floodplain Development Manual, 2005.
E2015/16795	2015-03-01	Belongil Creek Floodplain Risk Management Study and Plan	BMT WBM Pty Ltd	This Floodplain Risk Management Study (FRMS) draws together a wide range of floodplain management options which have been investigated and is the result of a detailed investigation and consideration of flood risk across the study area.
E2019/3138	2018-11-13	Technical Memorandum - Sandmining drain/track status and impact on Belongil catchment	Australian Wetlands Consulting Pty Ltd	Assessment of the disused sandmining track/drain system that runs north from the West Byron Sewage Treatment Plant (WBSTP). The aim of the assessment is to provide a report on the current status of the track/drain and its impact on the Belongil Creek catchment.

There is no evidence in any of the above-noted reports of any historical sand mine drains in the vicinity of the Byron Bay STP or wetlands.

Further to Question 2, above, BSC staff found no evidence in any of these documents regarding any impact from the Byron Bay STP or wetlands to the Industrial Estate or Belongil Catchment due to a sand mining drain intersecting operational lands. Regardless, if segments of any historical drains from sand mining still exist, it is highly improbable that are still directly hydraulically connected to the Belongil Catchment because of the soil compaction from railway ballast, Ewingsdale Road and the Industrial Estates compacted buildings foundations and compacted road bases.

Council has no evidence from water quality monitoring that there is uncontrolled short-circuiting of nutrients from the Byron Bay STP to the Belongil Catchment.

Res 19-540 point 4:

When this information has been assembled, Council consider a site visit for committee members.

Staff Response: Recommended when information from Byron Bay Historical Society has been received.

Res 19-540 point 4:

That listing for Byron Bay STP Catchment of sewage load resulting from Development Consents after 9 December 2002 (or similar) be brought to the next WWSAC

Staff Response: See report I2019/2155

Res 19-540 point 5:

That Council note that Byron Bay STP capacity was reassessed in recent years

Staff Response: Noted

Res 19-540 point 6:

That Council note that when ADWF reaches 80% of plant capacity (assessed in 2002 as 6.95 ML/day) Condition 6 requires action by Council.

Staff Response: Noted, See report I2019/2155 on this agenda.

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.4 - Attachment 1

West Byron Sewage Treatment Plant Wetlands

Cell J Infiltration Trial

8^th March 2005 to 6^th April 2005

Michael Bingham and John Murtagh

Background:

West Byron Sewage Treatment Pant Wetlands are a composite of five complete, constructed effluent polishing wetland cells (cells E, F, G, I, J) one incomplete (D) and another utilised as wildlife habitat (H).

Cell E (2.07ha) was completed including planting with five varieties of wetland macrophytes (reeds) December 23 2005. Cells F (2.14ha) and G (1.96ha) are planted primarily with melaleucas and are bisected by what is known as the ‘central channel’, they have been in use since the early nineties. Cell I (3.77ha) encloses the ‘typha’ paddock that developed when effluent discharged from the old wetlands and wetted this area over the years.

Cell J (3.51ha), the subject of this trial, was completed in April 2004 and is planted out with six varieties of wetland macrophytes.

Cell J description:

Cell J is 3.51ha in area; it is surrounded by berms constructed with clay cores on the all sides excluding the inflow (northern) side. Cell J has a sloping bed of 1:1000; this means that the base at the outflow (southern end) is 300mm lower than the inflow end.

The cell base was covered with a variable 300mm layer of blended topsoil medium for the macrophytes to grow in. This topsoil was a blend of 50%sand, 40% organic material (sludge, soil and composted plant matter) and clay (10%).

Cell J is filled utilising a ‘bubbler’ pipe system and outfall is controlled using six adjustable ‘flood gate’ structures, another floodgate connects cell I and J towards the southern end of the common berm. The invert of the outfall structures is 3.29m AHD. The base is higher, along most of its length, than the base of cell I. Cell I was mostly dry throughout the trial and no seepage was evident from cell J into cell I along the common berm.

At the commencement of the trial Cell J had approximately 90-95% vegetation cover comprising of the six wetland macrophyte species and a variety of terrestrial weed species. (Macrophyte planting numbers, layout and species list are available if required).

Purpose:

Since none of the wetland cells have been lined with impervious material the infiltration trial was conducted to quantify water losses through evapotranspiration and percolation. The results and conclusions should provide useful information in discerning the wetlands water budget and may also provide some confidence to government agencies such as DIPNR regarding impacts on water tables.

Method:

Cell J was ‘filled’ until water covered the top end of cell J at a depth of approximately 200mm; this meant that water depth at the outfall (southern) end of cell J was approximately 500mm.

The cell was left for 4 days to allow water levels to equalize since the macrophytes provide some hydraulic resistance to the spread of water and could influence depth readings if measurements commenced immediately after flooding.

The cell was locked down to prevent accidental flows into the cell and measuring devices installed.

The measuring devices were composed of two 30 cm plastic rulers attached to two outfall structures. The rulers were set at the 20cm mark against permanent marks made on the outfall structures in the case that they may become dislodged they could be reset. Measurements to the nearest millimetre were taken daily. The time and measurement along with rainfall data were entered onto a spreadsheet along with any erroneous observations. Measurements were then converted to AHD.

Some on-site weather information was obtained from a local weather station. Unfortunately the station was offline for part of the trial; it was reinstalled after servicing on the 11^th of March. David Bonner provided the data collected since then. Evaporation was also estimated from the pan evaporation recordings at Alstonville weather station.

A water quality sample was taken from the cell before discharge of the waters on Wednesday the 6^th April.

Erroneous observations:

· After flooding the cell a wet spot developed along the eastern side of cell J, indicating some losses along this side these losses were considered minimal and could not be measured.

· A minor dribble was evident in the collection drain along the southern end this stopped after 7 days. These losses were also considered to be of irrelevant volumes.

· The trial was also utilised to control some of the terrestrial weeds. Considerable ‘browning off’ of terrestrial weeds such as paspalum was observed as the trial progressed.

Results:

Daily measurements of cell evaporation and the corresponding pan evaporation at Alstonville are given in the Appendix. Over several weekends, when the reading was a composite of several days, the mean daily evaporation and the corresponding mean pan evaporation were used in the analysis.

Because the cell evaporation measurements were taken at different times each day, individual recorded values spanned 19-31 hours. This introduced an error when the observed evaporation was treated as a daily rate but no attempt was made to adjust the rates because the errors were self correcting with an over-reading on one day being followed by an under-estimate on the next. Such errors increased the scatter around the trend line that was used in the analysis but did not have an important effect on the parameters of the line.

Figure 1 shows the scatter plot between pan evaporation at Alstonville and cell evaporation.

Figure 1 The relation between pan evaporation at Alstonville and cell evaporation.

The trend line had a slope of 0.83 and an intercept of 2.09 mm/d.

The slope represented the net effect of three factors:

1. The pan coefficient which adjusted for differences between pan and reference evapotranspiration, and would equal 0.8 for the exposure conditions at Alstonville;

2. The crop coefficient that adjusted for differences between reference and plant evapotranspiration. Published coefficients for wetland species (FAO 1998) vary during the year, rising to a mid-growing season value of 1.2 for a reed swamp in standing water, cattails and bulrushes.

3. Differences in evaporation rates between Alstonville and Byron Bay. Measurements of evapotranspiration (Penman-Monteith calculation) at Byron Bay during July 2002 to December 2003 averaged 153% of the pan evaporation at Alstonville (David Bonner pers comm.). The difference was even larger when the pan readings were adjusted to reference evapotranspiration to correspond to the Penman-Monteith calculation. The difference between the two localities is much larger than would be expected and should be confirmed before it is used to adjust Alstonville readings to Byron Bay equivalents. Until that is done, the reference evaporation rates at the two localities were assumed to be the same for the current investigation.

With a pan coefficient of 0.8 and an Alstonville/Byron Bay adjustment of 1.0, the slope of 0.83 translates to a crop coefficient of 1.04. That was accepted as a reasonable late-season coefficient for the wetland species, but also note the following discussion on seasonal effects.

The intercept of 2.09 mm/d was taken as an estimate of the mean percolation rate from the cell.

Extrapolation of results to other months

Several factors could change the cell evaporation in other months:

· Based on published coefficients, the crop coefficients could fall as low as 0.6 in the coldest months, and rise to 1.2 in the warmest. These changes would alter the slope of the trend line;

· The rate of percolation would vary with the hydraulic head between the water level in the cell and the height of the surrounding watertable.

Because of these effects, the estimates of cell water use could be improved by repeating the current experiment during mid-winter, and again during mid-summer.

Conclusions:

Using the current results and the mean pan evaporation at Alstonville, and ignoring any monthly differences in the crop coefficient and rate of percolation, the estimated monthly rate of water removal is given in Table 1.

Table 1 The estimated evapotranspiration and percolation from cell J using the parameters from the trend line in Figure 1, and ignoring the possibility of monthly changes in the crop coefficient and rate of percolation.

Month	Evapo-transpiration (mm/d)	Percolation (mm/d)	Total (mm/d)	Total (ML/mth)
January	4.81	2.09	6.90	7.5
February	4.15	2.09	6.24	6.1
March	3.57	2.09	5.66	6.2
April	2.74	2.09	4.83	5.1
May	2.24	2.09	4.33	4.7
June	2.08	2.09	4.17	4.4
July	2.24	2.09	4.33	4.7
August	2.91	2.09	5.00	5.4
September	3.82	2.09	5.91	6.2
October	4.23	2.09	6.32	6.9
November	4.57	2.09	6.66	7.0
December	5.06	2.09	7.15	7.8
Mean	3.41	2.09	5.50	72.0 /yr

Note:

The trial can easily be repeated whenever any of the mature cells are flooded for weed management.

APPENDIX - DAILY RESULTS

Recording date	Water removed (mm/d)	Alstonville pan evaporation (mm/d)
9/3/05	5	4.8
10/3/05	10	5.2
11/3/05	4	4.8
14/3/05	4.3	4.0
15/3/05	7.5	3.8
16/3/05	7.5	4.6
17/3/05	2.0	4.0
18/3/05	4.0	2.2
20/3/05	6.5	5.4
21/3/05	6.0	6.0
22/3/05	6.0	3.2
23/3/05	6.0	4.6
24/3/05	5.0	5.2
25/3/05	5.0	5.0
26/3/05	5.0	4.4
27/3/05	6.0	2.8
28/3/05	6.0	4.2
29/3/05	6.0	4.0
30/3/05	6.5	2.6
31/3/05	0.5	2.0
1/4/05	2.0	4.8
2/4/05	3.6	6.5
3/4/05	4.4	6.9
4/4/05	5.0	6.3
5/4/05	4.0	4.0
6/4/05	2.0	5.7

BYRON SHIRE COUNCIL

Staff Reports - Infrastructure Services 4.5

Report No. 4.5 Nutrient Loading in the Belongil

Directorate: Infrastructure Services

Report Author: Bryan Green, Water Sewer Systems Environment Officer

File No: I2020/56

Summary:

This report is in response to questions raised by the Waste and Water Sewage Advisory Committee, and subsequent recommendation that a report be submitted to Council to address the following:

18-690

Resolved that Council adopt the following Committee Recommendation(s):

Report No. 4.5 Nutrient Loading in the Belongil

File No: I2018/1704

Committee Recommendation 4.5.1

1. That Council note that consent conditions in clause 11 of the approval under Council res 02-1329 have been exceeded for short periods during the past 15 months

2. That Council determine a new methodology to calculate nutrient discharge into the Belongil to satisfy both Council Resolution 02-1329 and the Recycled Water Management Strategy 2017-27

3. That Council consider measures for overcoming these exceedances.

RECOMMENDATION:

That the committee note the report

REPORT

Committee recommendation

1. That Council note that consent conditions in Clause 11 of the approval under Council Re 02-1329 have been exceeded for short period during the past 15 months.

Clause 11 states

Nutrient Load Limit for West Byron STP

· Nutrient loads discharged to Belongil Creek, as measured at the outlet of the constructed wetland, shall not exceed 1,502 kg per year for Total Nitrogen and 300 kg per year for Total Phosphorus.

· Council shall continuously monitor nutrient loads discharged to the Belongil Creek. Determination of nutrient loads shall be based on a minimum of weekly sampling continuously averaged over a two month period, converted to an equivalent annual load.

· In the event that the equivalent annual nutrient load for either Total Nitrogen or Total Phosphorus exceeds 80% of the applicable limits specified in this Approval Condition, Council shall investigate feasible management strategies to reduce loads below 80%.

· In the event that the equivalent annual nutrient load for either Total Nitrogen or Total Phosphorus exceeds 100% of the applicable limits specified in this Approval Condition, Council shall meet to discuss appropriate courses of action to prevent further exceedances.

As this is an annual nutrient load calculation, it is not clear how the question relates to exceedance of nutrient loads for short periods during the past 15 months.

As per Council EPA licence 3404, Total Nitrogen and Total Phosphorus samples are collected fortnightly at the constructed wetland outlet and calculated using the EPA approved “source monitoring” method, EPA Load Calculation Protocol.

Nevertheless, if the question relates to the previous 15 months from the meeting date, 18 October 2018, then there was a 80% and 100% percentile Total Nitrogen exceedance during the April 2017 to April 2018 EPA reporting period. There may be other plausible reasons for these exceedances and will require further investigation however the most feasible may be the high rainfall during the March / April / May / June 2017 months and the February / March / Apr 2018 months. See table below.

During high rainfall events the flows through the wetlands are accelerated thereby reducing hydraulic retention time i.e. the high flows limit wetland plants ability to uptake the nutrients thereby skewing the monthly nutrient load output consequently the annual average nutrient loads.

2. That Council determine a new methodology to calculate nutrient discharge into the Belongil to satisfy both Council Res 02-1329 and the Recycled Water Management Strategy 2017-27.

In 2016 Council engaged Australian Wetlands Consultancy to design and install a v-notch weir to measure wetland discharge flows from EPA4.

The v-notch weir enabled accurate measurement of flows to support annual nutrient load calculations whereas previous wetland discharge flows were calculated using a complex water mass balance calculation which included rainfall and evapotranspiration.

3. That Council consider measures for overcoming these exceedances.

It is almost impossible to mitigate against increased nutrient loads during high rainfall events.

Literature reviews identify this is a natural occurring event across most natural wetlands.

Therefore it is not financially viable to conduct research and develop innovation to overcome these incidences.

The abstracts below are provided to further support the observations in the Byron Wetlands that it is challenging to prevent high nutrient release during high rainfall events and therefore are not unique when compared to natural wetland systems.

Committee members can access these abstracts via the link provided and purchase the full article at their own cost.

Resources:

1. Raisin G.W; Mitchell D.S; Croome R.L, September 1997,The effectiveness of a small constructed wetland in ameliorating diffuse nutrient loadings from an Australian rural catchment, viewed 15 25 January 2020 [https://www.sciencedirect.com/science/article/abs/pii/S0925857497000165]

2. Chescheir, G.M., Gilliam, J.W., Skaggs, R.W. et al. Nutrient and sediment removal in forested wetlands receiving pumped agricultural drainage water, viewed 15 January 2020, 30 [https://link.springer.com/article/10.1007/BF03160842#citeas]

Venue	Conference Room, Station Street, Mullumbimby
Date	Thursday, 30 January 2020
Time	11.30am