Advice AEE Agricultural Analysis Application Approachable Assessments Assimilation Assistance Biosolids Capability Client Communications Communities Compliance Compost Consents Consultation Contamination Coordinate Council Cultural Current Data Degradation Design Detention Developments Discharges Documentation Drafting E. coli Ecosystems Effects Engagement Environment Equipment Evidence Excellence Experienced Expert Facilitating Farming Wastewater Discharge Feasibility Fieldwork First-flush Fit-for-purpose Flooding Fun Geology Graphs Greywater Groundwater Guidelines Handbag Hazardous Hydraulics Innovation Interpretation Investigation Irrigation Land Landfills Landscape Land-treatment Leaching Lodge Management Monitoring NES Nitrogen Metals Microbiology Modelling Nutrients Onsite Optimisation Organics Overseer Papers Pathogens Phosphorus Plain-english Plans Waipukurau and Waipawa Preparation Presentations Project Quality Relevant Remediation Reports Research Review Sampling Wastewater Treatment Plants (WWTP) Scientific Septage Sludge Soil Community Reference Group Solutions Spreadsheets Standpipes Stormwater Strategy Support Surface Water Sustainability Systems Team Testing Timely Treatment Validation Wastewater Water Water-balance Waterways Hamish Lowe 30 August 2018
Overview • LEI – who? • Wastewater discharge basics • Previous Investigations • Waipukurau • Waipawa
Wastewater discharge Reticulation Treatment Storage Discharge
Wastewater discharge Receiving Environment Water Land
Wastewater discharge After wastewater has been treated, it needs to be discharged somewhere – it doesn’t just disappear or evaporate. The options are: • discharge to land • freshwater bodies (lakes, rivers, streams) • estuaries, and • the ocean.
Wastewater discharge The soils, terrain and adjacent water bodies determine the most feasible choices. The use of treatment can assist that choice. In CHB’s case, there are both land and river options.
Wastewater discharge Cultural Any discharge requires Ecological/ Social/ Environmental Recreational consideration and balancing Financial
Wastewater discharge
What others do Three categories of discharge Smallest caters There are 330 council • Land (54 M m³ of for 7 households; operated wastewater wastewater per year) Waiotira, treatment plants around • Water (352 M m³ of Northland; wastewater per year) the country, most Largest 1.2 million • Combined land and servicing populations people; Mangere, water (59 M m³ of <35,000 people. wastewater per year) Auckland
What others do NZ Wide Treatment Plant Discharges 1% 13% 11% 75% Unknown Water Discharges Land Discharges Combined Land/Water Discharges
Wastewater discharge Legend Cities>30,000 people Towns <5,000 people Settlement <750 people Discharge Method Irrigation to land River/stream Ocean
What others do NZ Surface Water Discharge Methods 21% 4% 75% River Unknown Ocean
What others do NZ Land Discharge Methods 2% 12% 0% 46% 36% 4% Unknown Trees Dairy Grazed Cut & Carry High Rate
Cultural vs tangata whenua Papatuanuku Allows for tapu to noa Consider states Waiora to Waimate
Wastewater discharge Irrigation - Deficit 100 % Land Irrigation - Non-deficit Irrigation - High-rate Rapid Infiltration Overland - Wetland Overland - Rock trench 100 % Water Pipe to Water
Wastewater discharge Water Land Direct to Water Indirect to Water Stay on Land River Wetland Forestry Small Holdings Large Holdings Are combinations possible or needed?
Principles of Land Discharge Land treatment of waste utilises the biological, chemical and physical properties of the land to further treat solid and liquid wastes and/or allow for land passage before reaching the underlying groundwater environment.
Principles of Land Treatment Land treatment is philosophically and practically distinct from land disposal. Land treatment seeks to Land disposal seeks only to utilise the environment to its dispose of the waste, using maximum extent treat the the land as a mechanism to waste, and in so doing may allow the waste to enter the also seek to improve the environment with limited or environment through the no treatment. characteristics of the waste.
Land Treatment systems
Land Treatment systems
Land - Investigations Location • How close is the land to the WWTP and how many sensitive neighbours are nearby? Terrain and elevation • Gentle slopes or flat land at similar height to WWTP are ideal. Soil properties • Water holding capacity, drainage rate, and particle size or soil type will determine loadings rates. • will wastewater irrigation integrate with the current land use (eg reserve, farm, or forestry) or Land use will the land use need to change to accommodate the wastewater irrigation? How will harvesting or stock grazing regimes integrate with irrigation regimes? Land area • how much land is available after subtracting buffers and unsuitable land? Climate • what are the normal and extreme ranges of rainfall, soil moisture deficit, and wind for each month and year? How will these variations limit irrigation design and operation? Values • Cultural, community, society
Land - System design Method of • Examples are subsurface dripper lines, fixed irrigators, travelling irrigators, border dyke or discharge infiltration basin, and (artificial) wetland basin. Application rate • Choices are deficit, non-deficit, rapid discharge for disposal to groundwater or wetland, and and purpose land passage prior to entering waterways. Timing of • What seasons, weather or soil moisture conditions will restrict or prevent discharges discharges (eg wet soils, heavy rain, or strong winds)?
Land - System design Storage for • How much storage volume will deferred be needed? Where will an additional pond be located? discharges Emergency or • What will happen to excess large storm wastewater volumes and what limits would be appropriate? contingencies
Land - System design In developing a land discharge system there are a series of basic design parameters which need to be considered. Basic design parameters: Cultural acceptability Hydraulic Loading Organic Loading Nutrient Loading Pathogen Loading
Principles of Water Discharge Discharge at a rate and composition that is within the seasonal assimilative capacity of the waterway.
Water - Investigations Location • How close is the land to the WWTP to the waterway Characteristics • Fast flowing, slow moving • How does flow go up and down and how does this match Flow seasonality wastewater flows Water use • Contact recreation, stock water • What is the level of nutrient enrichment existing and can Chemical status more be accommodated Biological status • What lives there – macroinvertebrates, fish, algae Values • Cultural, community, society
Water - System design Method of • Direct, indirect – pipe, near bank, gallery discharge What is the • Is it culturally acceptable and will nutrient enrichment influence quality impact and habitat Timing of • How is volume and treatment level adjusted to reflect flow and limitations discharges
Water - System design Storage for • Can storage be used to avoid deferred low flow discharges? discharges Emergency or • What will happen to excess large storm wastewater volumes and what limits would be appropriate? contingencies
Water - System design In developing a water discharge there are a series of basic design parameters which need to be considered. Basic design parameters: Cultural acceptability Hydraulic Loading Organic Loading Nutrient Loading Pathogen Loading
CLAWD Criteria for selecting • What criteria will be used to determine when the best times will be to discharge to these environments and Combined Land and how much is to be discharged each day? How will they Water Discharges be prioritised and balanced? • How much storage volume will be needed for times Storage for deferred when neither environment (land and water) can receive the discharges? Where will an additional pond be discharges located? Emergency or large • What will happen to excess wastewater volumes and what limits would be appropriate? storm contingencies
Benefits and Opportunities Is water a resource One system or multiple Can it be expanded Community should decide
Previous investigations In 2007 the Hawke’s Bay • Irrigating the existing quality effluent on to Regional forests that had been planted by the Regional Council at Waipawa and Council and Waipukurau. CHBDC together • Storing effluent when the forests were not capable of accepting the spray irrigation. investigated a • Discharging excess stored effluent into the forest Tukituki and Waipawa Rivers at times when treatment the river flows were 3 times the median flow. option. This consisted of:
Waipukurau Image Credit: Sarah Platt
Waipukurau
Waipukurau
Waipukurau
Waipawa Image Credit: Sarah Platt
Waipawa
Waipawa
Waipawa
Waipawa
Your choice Water Land
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