Best Practicable Environmental Option BPEO as a Tool for Decision Making

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Best Practicable Environmental Option (BPEO) as
a Tool for Decision Making
Scotland Water -Village Sewage Treatment
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Village Sewage TreatmentProject Brief

• To upgrade the pollution control for a small,
  rural community to meet the EUs Urban Waste
  Water Treatment Directive (UWWTD) effluent
  consent requirements
• To assess process performance alongside whole
  life costs
• To consider the appropriateness of the proposed
  treatment scheme and viable alternative Options
• To develop a suitable treatment solution based
  upon the principles of achieving Sustainable
  Development

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Village WwTW - Process Development Background

• Water Authority investigation into options for
  upgrade
• Options Appraisal - September 1998
• Options Appraisal Review - March 2001
• Value Management Workshop using the BPEO
  methodology to deliver
• Preferred Process Solution
• Maintain and demonstrate environmental quality
• Integrate Principles of Sustainable Development
  into the BPEO process

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The Decision Making Process

• Decision Making Process
• Generic Options Identifcation
• Selection Criteria
• Best Practicable Environmental Option
• Case Study - adding Sustainability

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Option Decision Process - WwTW
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Identify a range of possible technical
options which can do the job
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BPEO - Definition

• The Best Practicable Environmental Option (BPEO)
  methodology establishes, for a given set of
  objectives, the option that provides
• the most benefit or least damage to the
  environment as a whole,
• at acceptable cost,
• in the long term as well as in the short term.
• (Royal Commission on Environmental Pollution
  (RCEP) 1976)

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BPEO -National Regional Policy

• How we sold the concept as an acceptable form
  of evaluation
• One of the four principles in the SEPA National
  Waste Strategy
• Forms an integral part of the National Planning
  Policy Guideline No.10 Planning and Waste
  Management
• The Institute of Environmental Management and
  Assessment has seen the concept widely used to
  determine the best options for Wastewater
  Treatment and Site Selection
• A well-established concept used in part or whole
  by many organisations including MWH
• Recognised within the Borders Waste Management
  Strategy as methodology for developing the
  preferred option.

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BPEO - Typical Selection Criteria Hierarchy
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Example Environmental Ranking
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Example Operational Ranking
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Example Cost Ranking
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Example BPEO option selection
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BPEO - The Benefits

• Auditable
• Team Based Solution - mediates rage of views
• Nationally Recognised as a Decision-Making Tool
• Value placed on Non-Capital Aspects
• Structured Process
• Quicker

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Existing WwTW and Sewerage Infrastructure 100
people

• The 2 existing branch sewers drain south to the
  WwTW. This provides primary treatment via simple
  settlement. The effluent discharges via a
  soakaway system to the Local Burn.
• Sludge is taken off site by tanker for treatment
  prior to disposal.
• The WwTW is not well maintained, and fails to
  meet the existing discharge consent, which was
  based on limiting suspended solids.
• The current resident population is 81 and the 20
  year growth horizon prediction is for this to
  increase by around 30 to 105.
• The only significant commercial operation is a
  livestock transport company. They operate a basic
  washdown facility for their lorries, from which
  washwater is stored, then tankered to a regional
  WwTW. Daily volumes vary from 4 to 8m3, with
  Suspended Solids and BOD loads between 700 to
  2000mg/l and 120 to 260mg/l respectively.

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Effluent Discharge Consents- vary with the
discharge point

• Local Burn - the current discharge point, next to
  the WwTW. This is a minor watercourse which has
  been known to run dry. Consent BOD/SS are 5.5/5.5
  mg/l, with nitrification and phosphate removal
  required.
• Class B/C river - lies 3km or so east of the
  Local Burn discharge and has a more substantial,
  but still relatively low, average flow.However it
  has a nutrient pollution problem. Consent BOD/SS
  are 10/15 mg/l. No guidance has been given for
  nitrification or phosphate removal, but it is
  unlikely that these will be much less stringent
  than for the Local Burn.
• Main River - discharge at an existing outfall,
  which lies 4km to the south-east of the WwTW
  and is a major watercourse. The existing consent
  standard for this discharge is descriptive and
  unlikely to be changed by SEPA even with the
  Village flows added.

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The treatment Options we considered
Option 1 - Treat Locally by Reed Bed and then
Transfer for Discharge to the Main River
Option3 Treat Locally by MBR and then Discharge
to the Local Burn
Option 2 -Treat Locally by SAF and then Transfer
for Discharge to the Main River
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Options - what level of technology is right for
this community?
Reed Bed
Septic Tank
MBR
SAF
Lagoon
Increasing Technology
Decreasing Technology

• Mech/Elecl Intensive
• Enhanced Treatment
• Large Communities

• Low Tech
• Biological Treatment
• Small Communities

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BPEO - Typical Criteria Hierarchy
Develop to include wider sustainability criteria
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We extended BPEO, to include wider Sustainability
criteria...

• There are many (far too many 600?) suggested
  sets of sustainability criteria. In many cases
  criteria are chosen without a record of why
• We set out an audit trail explaining how we
  chose ours. We covered three sets, relevant to
  the key stakeholders
• 1. CIRIA RP 609 indicators (construction pilot)
• 2. UK Water Industry indicators (client)
• 3. The Land is Ours criteria (rural concerns)
• We selected criteria from these sets by
  eliminating
• - Non-applicable indicators (NA) - no
  relevance to this project
• - Duplicated Indicators (DUP) - do not
  double-count

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Rationalisation of criteria1. CIRIA Indicators
Non-applicable
Duplicate
We then chose the most relevant indicators
remaining - as highlighted.
Process (P) Site (S) Company (Co)
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Rationalisation of criteria 2. UK Water
Environmental Indicators
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Rationalisation of criteria3. The Land is
Ours criteria
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Eg Water quality calculations
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Eg Energy calculations for Greenhouse gas
emissions
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Eg External Costs calculations for
sludgetransport to Sludge Treatment Centre
Calculation of the external costs of climate
change, air pollution, noise, congestion and
public health of transporting sludge
(1) HGV is equivalent to a lorry/tanker (2) Costs
based on one-way journey when the HGVs are fully
loaded (3) Total climate change costs 0.00152
(climate change cost/t-km) x distance traveled x
weight (4) Noise, congestion and health costs
0.3215 (/HGV-km) x distance traveled x number of
tankers/lorries
(A similar calculation was done for the costs of
transport of dried sludge pellets)
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Options Sustainability Rankings
2
1
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Example - Errol, Scotland
Effective, Low-CostWastewater Treatment
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Simple - Process Flow Chart
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Simple and Fast Construction

• Fast, less complex and critical construction.
• Long-life, low-maintenance components.
• No equipment at the bottom of the cell that
  requires service.

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Robust Equipment
The equipment at the heart of the Aero-Fac System
is simple to operate and maintain
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Errol data is in line with 25yrs US experience
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What does a wastewater treatment plant really
cost?
Initial Capital Costs Annual Operating
Costs Total Costs
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What constitutes annual operating costs?

• Manpower/skill level
• Energy costs
• Service/routine maintenance
• Replacement parts
• Supplies/chemicals
• Sludge handling

All of the above are tied to inflation and
unpredictable as to future costs.
Would you sign a contract to operate an activated
sludge/ SBR plant for 10 or more years for a
fixed price?
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Aero-Fac annual maintenance
655