Transcript Document
Use of Geographic Information Systems (GIS) to
Calculate the Assimilative Capacity of Rivers to
Receive Proposed Discharges
Vivienne Kelly
Informatics & Reporting
Office of Environmental Assessment
t: 053-9160612
e: [email protected]
Presentation Outline
Introduction to Assimilative Capacity
Calculating Assimilative Capacity & Concentrations
Integrating Data Sources
Demonstration of GIS Assimilative Capacity Tool
Our Vision
Aim:
To develop environmental management systems that
assess and report on environmental quality using
integrated data from multiple data sources to provide more
intelligence to data users see and to increase the efficient
use of EPA resources.
Systems Developed:
Assimilative Capacity Tool
Risk Assessment Tool (Landfills, Quarries & Mines)
Assimilative Capacity
What is assimilative capacity?
… the ability of a body of water to cleanse itself; its capacity to receive waste waters or
toxic materials without deleterious effects and without damage to aquatic life or humans
who consume the water.
How is it calculated?
Simple calculation: (AC = (cmax – cbackground) x (F95 or DWF) x 86.4)
Environmental Quality Standards (EQS) (cmax)
Background Chemical Monitoring (cbackground)
Hydrometric Flow (95%iles & DWF)
EPA Role?
When assessing proposed discharges from IPPC, Waste and Waste Water Discharge
Applications, the EPA must determine the capacity of a waterbody to receive the
discharge and the potential environmental impacts.
Questions to Ask
Q2: What is the
concentration
following the
discharge?
UWWTP
River
Q3: What proportion of
the capacity has been
absorbed as a result of
the discharge?
Q1: What is the
capacity upstream
of the discharge?
Calculations
Assimilative Capacity:
Non Toxic Substances
AC = (cmax – cbackground) x F95 x 86.4
Dangerous Substances
AC = (cmax – cbackground) x DWF x 86.4
The capacity of a water body is calculated in kg/day
Variables:
AC
=
Assimilative Capacity
Cmax
=
Maximum permissible concentration (EQS)
Cbackground
=
Background concentration in river
F95
=
95%ile flow in the river (m3/sec)
DWF
=
Dry Weather Flow in the river (m3/sec)
Other Calculations
Resultant Concentration:
Cfinal =
(Cback x Vflow) + (Ceffluent x Veffluent)
(Vflow + Veffluent)
Capacity Absorbed:
% AC Absorbed =
(Cmax - Cback) - (Cmax - Cfinal)
(Cmax - Cback)
Cmax
=
Maximum permissible concentration (EQS)
Cfinal
=
Concentration in river after discharge of effluent
Cback
=
Background concentration in river
Ceffluent
=
Treated effluent concentration
Vflow
=
Volume of flow in river (95%ile or DWF – m3/sec)
Veffluent
=
Volume of effluent (m3/sec)
x 100
Waste Water Discharge Licence Substances
Relevant Substances
1
Suspended Solids
2
Ammonia (asNH4)
3
Biochemical Oxygen Demand
4
Chemical Oxygen Demand
5
Total Nitrogen (as N)
6
Nitrite (as N)
7
Nitrate (as N)
8
Total Phosphorous (as P)
9
OrthoPhosphate (as P)
10
Sulphate (SO4)
11
Phenols (C6H5OH)
Total Substances = 31
Total Calculations = 93
Per Discharge Point
Assimilative Capacity WebGIS Tool
The Assimilative Capacity Tool is a web based GIS
application designed to allow licence inspectors to calculate
the capacity of rivers and the surrounding environment to
receive pollutants from waste water treatment discharges.
Function:
Determine the capacity of waterbodies to receive specific pollutants
from proposed discharges.
Determine the potential impacts to the surrounding environment.
Improve the use of resources & produce better response times.
Support decision making.
Model Concept
AQUARIUS
Discharge Point
Hydrometric Station
Monitoring Station
River Flow Direction
Water Quality Data
ENGINE
Hydro Flow Data
Run
Calculation
Engine
Hydrometric
Data
Proposed Limit
Proposed Discharge
Assimilative Capacity at
Proposed Point of Discharge
Integration of Internal & External Data
Dangerous Substances
12
AtrazineCapacity Tool Demonstration
22 Cyanide
Assimilative
13
14
15
16
17
18
Dichloromethane
23
Flouride
Other UWWTP’s
River Data
Simazine
24 ofSelect
Lead
local
EPA
Toolbar Summary
Report
Window
Assimilative
EQS
With Exceeded
New EQS Prior
Monitoring Stations
Appears
Select
Environmental
Capacity
Tool
to
Discharge
Capacity is not Map of Discharge
Downstream
Report
Toluene
25 Upstream
Nickel
Exceeded.
Table
of
Contents
Monitoring Point
Monitoring Point Zoom to Area
of Interest
User
Selects
Conservation
Data
User
Selects New
Tributyltin
26 Zinc
Zoom to Area
Required
Report
EQS, Saves
and
Re-runs Report of Interest
Summarry Information
Xylenes
27 Boron
on Discharge
Option to
Change EQS
Demonstration
Arsenic
Hydro Data
19
Chromium
20
Chromium
21
Copper
28
Cadmium
Click to Highlight
III
29 Mercury
Station
Map
SelectonPoint
Discharge
Discharge Point
Water Quality
IVClick Next
30 Up &Selenium
Down Stream
31
Barium
Caveat
Decision Support Tool
Indication of waterbody capacity, not absolute rule
Inspectors must have full understanding of EQS for a site
and ensure appropriate data used in any calculation
All borderline cases should be examined in full
Improved Resource Use
EPA Aim: To increase the efficient use of EPA
resources
Manual Effort: 4-6 days
No. of Discharges: 177
Approx. Time to Calculate Manually: 3yrs
Total Time using AC Tool: 4 days
Development Team
EPA Team:
Breen Higgins
Gavin Smith
Fiona O’Rourke
Deirdre Kirwan
Tom Stafford
Ozan Emem
Jason Larkin
Claire Byrne
Aisling McElwain
George McHugh
Compass Team:
Ken Dowling
Pavel Janda
Seth Girvin
Maurizio Taddei
Mick Lennon
THANK YOU