Presentation Outline Site/Facility History CVRD Central Sector - - PDF document

Duncan/North Cowichan Joint Utilities Board Wastewater Treatment Lagoons 1

Joint Utility Board Sewage Treatment Plant: History, Treatment Process, and Performance Overview

Presentation to: Cowichan River Stewardship Roundtable By: Clay Reitsma, M.Eng., P.Eng. November 15, 2018

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Presentation Outline

• Site/Facility History
• CVRD Central Sector Liquid Waste Management Plan (CSLWMP)
• JUB Administration
• Treatment Process Description
• Performance of Treatment Facility
• Questions

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Duncan/North Cowichan Joint Utilities Board Wastewater Treatment Lagoons 2

History

• Jan 1961: Duncan constructed three:cell lagoon on Cowichan

Tribes Reserve lands with outfall to Cowichan River.

• Jan 1968: District of North Cowichan (DNC) constructed two:cell

lagoon beside Duncan lagoon, on Cowichan Tribes Reserve lands, with separate outfall to Cowichan River.

• Jan 1974: Surface aerators installed in Cell #1 and Cell #4.
• Jul 1978: Duncan and DNC lagoons combined into a single plant

with one new outfall to river. Joint Utility Board (JUB) formed.

– The JUB Sewage Treatment Plant (STP) is run jointly by Duncan and DNC.

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History

• Oct 1979: Single permit PE:1497 issued for joint operation.
• Mar 1993: Cell #1 was dredged.
• Dec 1993: New aerators added to Cell #2.
• Jul 1998: Interim Lease Agreement signed.

– Between Duncan, DNC, Cowichan Tribes and Tribes’ Certificate of Possession Holders. – 20 yr term (commenced Jul 1, 1996).

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History

• May 11, 2000: Ministry of Environment approved CVRD

CSLWMP.

• May 2000: Major upgrade to treatment system ($4,500,000):

– new fine bubble aeration system – two 175 kW blowers – new screens and degritting facility – raised all berms – Cell #1 dredged

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History

• Dec 2001: JUB STP Capital and Operating Agreement signed:

– Between Duncan, DNC, Cowichan Tribes and CVRD.

• May/Jul 2002: CVRD CSLWMP amended:

– Cowichan Bay sewer connected to lagoons. – Options other than water reclamation to be considered in order to reduce effluent phosphorus load to Cowichan River.

• Oct 2002: Alum system installed to reduce phosphorus load to

Cowichan River ($300,000).

• Nov 2004: Cowichan Bay sewer system connected to JUB STP.

Cowichan Bay STP (@ Hecate Park) decommissioned.

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History

• Aug 1, 2011: New lease agreement signed.

– Lease between DNC/Duncan (the JUB) and Cowichan Tribes. – Lease is for the use of the land where the JUB STP resides. – Lease agreement is for 49 years with an option to renew. – Includes a commitment make reasonable effort to remove the JUB STP outfall from the Cowichan River in 10 years (by 2021).

• 2010: Log jam/gravel removal at outfall pipe.

– Removed large log jam/gravel deposit and installed erosion protection armouring and training spur ($880,000).

• 2011/2012: JUB Dike constructed.

– 900 m of diking constructed around JUB STP to protect it and Duncan/Reserve lands from flooding ($2,500,000).

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History

• Nov 2013: Capacity review undertaken.

– Capacity of the plant increased by 25% (capacity based on Equivalent Residential Units or ERUs). – ERUs allocated to jurisdictions using the facility in proportion to their current ERU share.

• 2016/2017: Upgraded screening and disinfection systems.

– Upgraded to a finer screening system. – Removed gaseous chlorine/sulpher dioxide gas systems with liquid chlorine and sodium metabisulfite systems. – Installed new valve and flowmeter in outfall pipe. – Total cost: $920,000.

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CVRD Central Sector LWMP

• High level plan for the management of sewage in the core

urban area of the Cowichan Valley.

• Approved by the Minister of Environment on May 11, 2000.

– Stage 1 completed Oct 1995. – Stage 2 completed Nov 1998. – Stage 3 completed May 2000. – Amendment #1 (2001): Connect Cowichan Bay sanitary sewer system to to the JUB STP. – Amendment #2 (2001): Allow for options other than water reclamation to reduce the JUB STP effluent phosphorus load to the Cowichan River. – Amendment #3 (2015; Approval Pending): Relocate the JUB STP

• utfall from the Cowichan River to Satellite Channel.

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CVRD Central Sector LWMP

• The Plan has three main goals:

– To protect human health and the environment through the provision of appropriate liquid waste treatment facilities. – Reduce the liquid waste stream in accordance with reduce, reuse, and recycle.

• The Plan recommends the following general actions:

– Enact source control programs (bylaw/education). – Enact volume reduction programs (inflow and infiltration repairs, water conservation, education). In progress.

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CVRD Central Sector LWMP

• JUB STP

– Reduce phosphorus discharge to River. Done. – Sample and monitor Cowichan River water annually upstream and downstream of the discharge. Done. – Develop Biosolids Management Plan.

• Cowichan Bay System

– Connect to JUB STP and decommission Cowichan Bay STP. Done.

• Maple Bay Servicing

– Plan for future provision of collection sewers within Maple Bay pumped to Maple Bay Road sewer system. Partly done; new STP in Maple Bay.

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CVRD Central Sector LWMP

• Rural Area Servicing

– Protect rural areas from urban type development. – Assess problem septic areas. – CVRD to develop brochure for on:site sewage system management. – The CVRD to plan to accept boat pump out discharges at Cowichan Bay wharf. Done.

• New Treatment Plant and Outfall (Long Term)

– Investigate sites for a new STP to service 70,000 people. Existing plant currently serves about 26,000 people. Done. – Investigate outfall routing options for the removal of the Cowichan River discharge and for a new discharge to Satellite Channel. In progress. – Undertake a public education and consultation process to support the treatment plant site selection and outfall study work. Outfall in progress.

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JUB Adminstration

• What is the Joint Utility Board?

– DNC and Duncan are co:owners of the JUB STP. – Board members from DNC and Duncan Councils (2 members each). Chair position rotates annually. – Board oversees the management of the JUB STP. – Board recommendations referred to DNC and Duncan Councils for approval. – CVRD Area D, CVRD Area E, and Cowichan Tribes are users of the facility and send non:voting members to the Board meetings. Their input at meetings is considered by the Board.

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JUB Administration

• How are things paid for?

– JUB STP capacity is expressed in Equivalent Residential Units (ERUs). – ERUs have been allocated to each jurisdiction using the facility. – Capital projects funded based on ERUs owned. – Operation funded based on ERUs connected. – 12,762 ERUs of 17,300 ERUs of capacity being used as of Dec 31, 2017.

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JUB Administration

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JUB Administration

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Duncan/North Cowichan Joint Utilities Board Wastewater Treatment Lagoons 9

The Treatment Process

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Substances the Lagoons are Designed to Treat

Wastewater (NOT Storm Water)

Stormwater should NEVER be directed to a wastewater treatment plant.

Organics (Carbonaceous Biochemical Oxygen Demand : CBOD5)

Organics can reduce dissolved oxygen concentrations in rivers, stressing fish.

Total Suspended Solids (TSS)

TSS can clog spawning beds.

Total phosphorus (TP)

TP can causes excessive algae growth in rivers, reducing dissolved

• xygen concentrations, stressing fish.

Bacteria and Viruses (Indicator Organism is Fecal Coliforms : FC)

Bacteria/viruses can cause health issues in recreational waters and can render shellfish inedible.

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Treatment Flow Path

Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6

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Treatment Unit Processes

The treatment system has many different components that work together to treat the wastewater. They include:

Screening Removes larger inorganic material (plastics, rocks). Degritting Removes heavier/finer inorganic material (sand). Oxidation Converts organics to micro:organisms for subsequent removal by sedimentation. Settling Settles out micro:organisms. Alum Addition Removes phosphorus. Chlorination Kills bacteria and viruses in the process water. De:Chlorination Removes residual chlorine byproducts from the effluent prior to discharge to the river.

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Treatment Unit Processes

Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6

Screening & Degritting Oxidatio n Oxidation / Settling Settlin g Alum Addition Settlin g Disinfectio n De- Chlorination

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Treatment Unit Processes: Screening

Removes larger inorganic material (plastics, rocks).

• Fine perforated plate screen screens out larger inorganic material.
• Screened wastewater passes through to the degritting process.
• Captured solids (screenings) are washed, pressed/dewatered, and conveyed into a covered

holding container.

• A fan draws odourous air from the system and scrubs it through a biofilter.

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Treatment Unit Processes: Degritting

Removes heavier/finer inorganic material (sand).

• Total of four grit channels.
• Flow velocity is maintained at 1 ft/sec to allow heavier/finer inorganics to settle.
• Grit is removed from the channels monthly and deposited into Cell 6.

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Treatment Unit Processes: Biological Oxidation (Cell 1)

Converts organics to micro:organisms.

• Wastewater flows from the grit channels to Cell 1.
• Purpose is to convert organic matter (which exerts an oxygen demand in receiving waters)

to micro:organisms (which will settle in subsequent ponds).

• By settling out the micro:organisms in subsequent cells, the organic matter is removed from

the liquid.

Cell 2

Cell 1

Cell 3 Cell 4 Cell 5A/5B

Cell 1

Cell 2

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Treatment Unit Processes: Biological Oxidation (Cell 1)

Converts organics to micro:organisms.

• Air is provided to mix the water and bring micro:organisms in contact with their food

(organic matter).

• Air is also provided as a source of oxygen. The micro:organisms need oxygen to survive.
• Air diffusers hang from flexible laterals that float on the surface of Cell 1.
• Flexible laterals are designed to move from side to side to maximize mixing. This

significantly reduces aeration costs.

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Treatment Unit Processes: Biological Oxidation (Cell 1)

Converts organics to micro:organisms.

• Air is provided by two 150 kW blowers .
• One blower is a standby unit. There is provisions for a third blower in the future when

additional aeration diffusers are added (can add 50% more diffusers).

• The blowers take air from the atmosphere, pressurize it and send it to the diffusers that are

submerged in Cell 1.

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Treatment Unit Processes: Biological Oxidation (Cell 1)

Converts organics to micro:organisms.

• The diffusers have tiny holes that release small bubbles.
• The bubbles mix the water.
• The bubbles also dissolve into the water and provide oxygen for the micro:organisms.
• This is a fine bubble system. More efficient for transferring oxygen to water.

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Treatment Unit Processes: Settling (Cells 2 & 3)

Settles out micro:organisms that were grown in Cell 1.

• Process water from Cell 1 flows to Cells 2 and 3.
• After organics are converted to micro:organisms, the organics must be extracted from the

process water to reduce CBOD5 and TSS in the effluent.

• Since the micro:organisms are heavier than water they settle out.
• Every 10 to 15 years the settled material is removed and deposited in Cell 6.

Cell 2

Cell 1

Cell 3

Cell 4 Cell 5A/5B

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Treatment Unit Processes: Alum Addition

Removes phosphorus.

• Process water flows from Cell 3 to the flash mixing/flocculation channel.
• Phosphorus is a nutrient that is removed using a chemical called liquid alum. Phosphorus

exists in dissolved and particulate forms.

• Alum reacts with dissolved phosphorus to form a heavy sticky particle (floc).
• The flocs stick to other solids (including particulate phosphorus) and settle out.

Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A/5B

Flash Mix / Floc Channel Alum Storage & Pumps Alum Storage

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Treatment Unit Processes: Alum Addition

Removes phosphorus.

• Alum is pumped to the flash mixing/flocculation channel.
• The alum is rapidly mixed with the process water using flash mixers.
• The process water is gently mixed in the flocculation channel to form floc particles.
• After exiting the flocculation channel, the floc particles begin to settle.

Alum Pumps Flash Mix / Floc Channel

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Treatment Unit Processes: Chlorination

Sterilizes the process water.

• Chlorine solution (sodium hypochlorite) is injected in the channel between Cells 4 and 5A.
• The chlorine concentration is monitored at the outlet of Cell 5A to ensure the concentration is

high enough to disinfect the effluent.

Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6

Disinfection De-Chlorination Sodium Hypochlorite Metering Pumps Sodium Hypochlorite Storage Tanks and Containment Area

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Treatment Unit Processes: Dechlorination

Removes excess chlorine from the effluent.

• Sodium metabisulphite solution is injected at the outlet of Cell 5B.
• The chlorine concentration is monitored at the outlet of Cell 5A to ensure there is no chlorine left

in the effluent.

Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6

Disinfection De-Chlorination Sodium Metabisulphite Storage Tanks & Metering Pumps

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Performance

• Regular testing as required by MoE:

– Effluent – River upstream of outfall. – River downstream of outfall.

• Source control bylaws:

– DNC, Duncan, and the CVRD. – Prohibit high strength/hazardous discharges to the treatment system.

• DNC, Duncan, and the CVRD have been working on

reducing inflows and infiltration in sewers to reduce flows to the treatment facility.

An annual report, summarizing the performance of the treatment process and impacts to the river, is provided to MOE and Cowichan Tribes.

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Effluent Flow

• Calculated as average annual values.
• New flowmeter installed in 2016.

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Effluent Quality: CBOD5

• Calculated as average annual values.
• Want the effluent (blue line) to be BELOW the limit (red line)
• Average is 11 mg/L (37% of limit).

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Effluent Quality: TSS

• Calculated as average annual values.
• Want effluent (blue line) to be BELOW the limit (red line)
• Average is 15 mg/L (38% of limit).

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Effluent Quality: Fecal Coliforms

• Calculated as average annual values.
• Want effluent (blue line) to be BELOW the limit (red line)
• Average is 82 CFU/100 mL (41% of lower limit). Poorer results from 2002 to 2004 due to

partial nitrification.

• Average is 44 CFU/100 mL (22% of lower limit) since 2005. Partial nitrification resolved.

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Effluent Quality: Total Phosphorus

• Calculated as average annual values for the period July 1 to September 31.
• Want effluent (blue line) to be BELOW the limit (red line)
• Average is 9.3 kg/d (52% of limit) since 2003. Alum system installed in 2003.

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Effluent Quality: Toxicity

• Calculated as average annual values.
• Want effluent (blue line) to be ABOVE the limit (red line)
• Average is 97% survival since of fish based on 96h LC50 (100% Effluent) test.

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Effluent Quality: Summary

• Compliance testing is based on point by point data except in the case of Fecal Coliforms

tested against the swimming standard limit of 200 CFU/100 mL which is based on the median of 7 samples. Statistics (Effluent Compliance)

Parameter Operating Certification Limit Total Samples Samples in Comp % In Comp CBOD5 100% <= 30 mg/L 779 769 99% TSS 100% <= 40 mg/L 800 787 98% TP 100% <= 18 kg/d (Jul 1 to Sep 30) 227 218 96% FC (2005 to 2017) 100% <= 800 CFU/100 mL 580 579 100% 100% <= 200 CFU/100 mL (Median of 7 Samples) 580 578 100% Toxicity 50% Survival in 100% Effluent f 96 Hours 86 86 100% Total 3052 3017 Weigthed Avg Compliance Rate 99%

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River Water Quality: Fecal Coliforms

• Calculated as average annual values.
• Want downstream results (thin orange line) to be BELOW the upper limit (thick red line).

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River Water Quality: pH

• Calculated as average annual values.
• Want downstream results (thin orange line) to be BETWEEN the upper limit (thick red

line) and lower limit (thick orange line).

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River Water Quality: DO

• Calculated as average annual values.
• Want downstream results (thin orange line) to be ABOVE the lethal limit (thick red line)

and impaired limit (thick orange line). Limits are for salmonids.

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River Water Quality: Summary

Statistics (River Compliance)

Parameter BC Water Quality Guideline Limit Total Samples Samples in Comp % In Comp Total Samples Samples in Comp % In Comp FC <= 200 CFU/100 mL (Recreational Standard) 55 53 96.4% 95 93 97.9% pH Between 6.5 and 8.5 246 225 91.5% 247 227 91.9% DO >= 5.00 mg/L Lethal Limit (Salmonoids) 172 171 99.4% 170 170 100.0% >= 7.70 mg/L Impaired Limit (Salmonoids) 172 171 99.4% 170 170 100.0% Total 473 449 512 490 Weighted Avg Compliance Rate 94.9% 95.7% Upstream Downstream

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Environmental Impact of Lagoons

• Effluent Quality

– VERY GOOD (meets limits in 99% of samples; 3017 out of 3052 samples).

• River Water Quality

– No significant difference in WQ upstream to downstream of outfall (compliance w WQGs is 94.9% upstream, 95.7% downstream). – Typically when downstream results DO NOT meet BC WQG limits it is because upstream results DO NOT meet the BC WQG limits. – There is a small localized impact downstream; a small algae bed. Hard to measure but it size of the algae bloom has shrunk due to decreased phosphorus load to River.

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Glossary

Item Definition 96h LC50 (100% Effluent) Test where trout are placed in 100% efluent for 96 hours under oxygenation. At least 50%

• f the trout must survive to in order for the effluent to be declared non-toxic.

Avg Average BC WQG British Columbia Water Quality Guidelines CBOD5 5 Day Carbonaceous Biochemical Oxygen Demand CFU Coliform Unit Comp Compliance CSLWMP Central Sector Liquid Waste Management Plan CVRD Cowichan Valley Regional District d Day DNC District of North Cowichan DO Dissolved Oxygen ERU Eequivalent Residential Unit FC Fecal Coliform JUB Joint Utility Board kg Kilogram L Litre m3 Cubic Meter mg Milligram STP Sewage Treatment Plant TP Total Phosphorus TSS Total Suspended Solids

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