NCS000482_ENG 3362 Dry Weather Screening_20220526

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Dry Weather Screening
PURPOSE
In accordance with the City of Monroe IDDE Plan, Stormwater outfalls are periodically
inspected during dry weather for the presence of illicit discharges and illegal connections.
Stormwater outfalls should be inspected, tested, and ranked according to the procedures
described herein. The outfall screening process can also be used to collect data to update
the stormwater outfall map.
If field crews encounter an obvious illicit discharge of sewage, or a potential hazardous
substance, the crew should stop the outfall survey and immediately track down the source
and immediately contact appropriate authorities.
Refer to Illicit Discharge Detection and Elimination, a Guidance Manual for Program
Development and technical Assessments, by The Center for Watershed Protection and
Robert Pitt, University of Alabama, 2004, or more recent, for further detail and guidance.
PLANNING
Prepare for the inspection of outfalls by doing the following:
Inspections are to occur during dry weather (no runoff producing precipitation in
last 48 hours). The Community Collaboration Rain, Hail, & Snow Network and
Weather Underground are sources that can be used to track recent rainfall to
ensure that dry weather precedes outfall inspections.
Links:
g/ ..... p.ea_spx?state=NC
:....ps.e....._www.erar car d_ 7s.- ..._�_q. s Viewma
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2. Conduct during late fall or early spring, if possible, during leaf -off conditions except
for other conditions, such as where swimming pool discharges are suspected.
3. Conduct inspections with at least two staff per crew.
4. Do not enter private property without permission.
5. Calibrate all field equipment as required.
EQUIPMENT LIST
The following is a suggested equipment list for Outfall field reconnaissance. This list is in
no way exhaustive and meant to be a guide only.
1. PERSONAL
• Telephone
• City identification
• Hat
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2. SAFETY
• Safety vest
• Hand sanitizer
• First aid kit
• Disposable gloves
• Trash bag boots
• Bug repellant / sunscreen
• First Aid Kit
3. GENERAL TOOLS (substitute electronic equivalents as available)
• System map
• GPS unit
• Data sheet or I -pad
• Digital camera
• Flashlight
• Machete
• Permanent marker
4. FLOW MEASUREMENT
•
Tape measure or folding ruler
•
Ping pong ball
•
Water jug with volume marked at 1 gallon
•
Stopwatch
5. FIELD TESTING / SAMPLING KITS AND DIRECTIONS
•
Temperature probe
•
pH probe
•
Ammonia test kit
•
Dissolved Oxygen test kit
•
Conductivity probe
•
MSDS sheets
•
Spare batteries for probes
6. SAMPLE
COLLECTION
•
Five 1-liter (polyethylene) sample bottles
•
Bottle labeling
•
Chain of custody forms
•
Cooler with ice
•
Waste bucket
SCREENING PROCEDURE
For details on specific tests and measurement, refer to test kit and sampling probe
directions.
► Flow Measurement
► pH and Temperature Measurement
► Ammonia Test
► Dissolved Oxygen Test
► Conductivity / TDS Measurement
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GENERAL PROCEDURES
1. Locate Outfall
a. Find outfall location
b. Ensure outfall is accessible
c. Inspect outfall only if safe to do so
d. Locate the outfall in the field
e. Drop a pin (Locate the outfall on GPS)
2. Photo
Take a digital photo of the outfall
3. Field Data Collection
Characterize the outfall by recording information on the Outfall Reconnaissance
Inventory Sample Collection Field Sheet (Attachment 1). Refer also to Table 1 - a
Guide for Completing the Outfall Reconnaissance Inventory Sheet.
4. Results of Collection
Once the Outfall Reconnaissance Field Sheet is completed, all test results are forward
to the Contact Stormwater Compliance Coordinator for review.
Table 1
Guide for Completing the Outfall Reconnaissance Inventory (ORI) Field Sheet
Section on Form
Data Collected
Section 1
. Watershed
. Recent rainfall
Background Data
. Date and time
. Longitude and latitude
• Outfall number
. GIS information
• Investigators names
• Land use
• Air temperature
Section 2
. Type of pipe / drainage structure or ditch
Outfall Description
. Flow description
Section 3
• Flow measurement
Qualitative Characterization
. Ammonia (field test kit)
(Field data for flowing
. Dissolved Oxygen (field test kit)
outfalls)
. Conductivity(probe)
• pH (probe)
• temperature (probe)
Section 4:
. Odor
Physical Indicators for
. Color
Flowing Outfalls
. Turbidity
(Visual observation)
. Floatables
Section 5:
• Outfall Damage
Physical Indicators For All
• Deposits / Stains
Outfalls
. Abnormal vegetation
• Poor receiving pool quality
. Pipe benthic growth
Section b:
Flagged I Rating I Criteria
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1,01, *' 1 11416 336)
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A more detailed discussion is provided for each section as follows:
a. Background Data (Field Sheet - Section 1)
Investigators names, watershed name, Outfall No., date, time, GPS
coordinates, weather, land use, etc.
b. Ouffall Description (Field Sheet - Section 2)
o Pipe / ditch type and dimensions, etc.
If field crews encounter an obvious illicit discharge of sewage, or a potential hazardous
substance, the crew should stop the outfall survey and immediately track down the
source and immediately contact Stormwater Compliance Coordinator
The crew should document the discharge with photos, descriptions, measure flow, and
take samples for laboratory analysis if safe to do so. Once documentation is
completed, email the Stormwater Compliance Coordinator to proceed with the
recording of the information in ACCESS.
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c. Quantitative Characteristics (Field Sheet- Section 3)
IF FLOW IS PRESENT:
If flow at an outfall is present, then visual physical observations are recorded
and screening level measurements are collected using field test kits of portable
meters.
For probes, measurements should be made from the sample bottle that
contains the captured flow. (except for temperature, which should be
measured in the flow if possible). If a visual condition assessment indicates the
presence of pollutants, it may be necessary to collect a sample for laboratory
analysis.
Procedures to follow if flow is present:
• Measure the flow from the outfall
• Measure Temperature using the pocket Probe
• Measure the pH using the pocket Probe
• Measure Ammonia using the test kit
• Measure the Dissolved Oxygen using the test kit
• Measure the Conductivity using the pocket probe
Record the data and compare the Temperature, pH, Ammonia and
Conductivity to the benchmarks using SOP ENG-3362b - Outfall Dry Weather
Flow Benchmark Guide.
d. Physical Indicators for Flowing Outfalls (Field Sheet- Section 4)
Indicate the presence, description and severity of odor, color, turbidity,
and floatables.
• ODOR
o Odor of the water at the outfall should be assessed by all
members of the field crew and a consensus and the
presence and severity of the odor should be made.
o Be sure that the odor noted is coming from the flow, not the
surrounding area.
Severity Score
Severity
Description
Rating
Faint odor
1
Crew cannot agree on
presence or origin
Moderate smell,
2
easily detected.
Strong, can detect it
3
Crews can smell the odor from
from a distance.
a considerate distance away.
• COLOR
Colors often help identify industrial discharges.
o Collect a sample of the discharge in a clear container.
o Hold the sample up to the light.
o Look for downstream plumes of color
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Description
• TURBIDITY
Turbidity is a measure of the cloudiness, or how well light can pass
though the water. It should not be confused with color, although it
may be relate to color.
Observe the turbidity of the water in the sample collection
container. Also, look for the turbidity in the plunge pool and
downstream receiving water.
Severity Score Severity Rating
Slight cloudiness 1
Cloudy 2
IM Opaque 3
• FLOATABLES
Floatables may typically include suds, oil sheen, and sewage.
(Trash and debris are not typically included in the Floatable
observation, but should be noted.
If Sewage is highly suspected, a severity of 3 should be
assigned.
Suds are rated based on their foaminess and staying power. Some
streams have naturally occurring foams that form by decaying
organic matter.
Description
Source indicator
Severity
Rating
Only associated with
Natural organic
0
high flows and elevation
decay
drop or turbulence.
Suds do not appear to
Low
1
travel, very thin foam
layer
• Heavy suds, thick
Sewage or
3
• Suds travel far down
washwater
stream without
breaking up.
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• Accompanied by a
strong organic odor
• Fragrant odor Laundry / wash 3
water
Oil sheens are ranked based on their thickness and coverage.
Some surface sheens are created naturally in stream by microbes,
including iron bacteria.
Type
Description
Severity
Rating
Natural sheen
Breaks (cracks) up easily
1
Petroleum sheen
Swirling, rainbow color,
2 or 3
comes back together
when disturbed.
e. Physical Indicators for All Outfalls (flowing and non -flowing)
(Field Sheet - Section 5)
Use the Field Sheet to record the description of any outfall damage,
deposits, staining, abnormal vegetation, poor water quality and pipe
benthic growth if present.
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5. Evaluation of Data and Outfall Rating
e. Overall Outfall Characterization (Field Sheet- Section 6)
Rate the Outfall - Overall Outfall Characterization
Based on the observations, data collected and comparison to
benchmarks, each outfall should be classified.
Not flagged
0 Unlikely
Non -Flowing outfall
No signs of dry weather flow or pollution
Flagged Outfalls (may or may not be flowing at time of inspection)
1 Potential
Flowing or non -flowing outfall
Presence of 2 or more characteristics, benchmark parameter
indication, or best judgement.
2 Suspect
Flowing outfall (may be intermittent)
Severity of 3 with one or more indicators, benchmark parameter
indication or best judgement.
3 Obvious (may be intermittent)
Flowing outfall with high severity of one or more physical indicators,
sample shows benchmark parameter indication; or source is directly
observed, or confirmed.
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6. Water Sample Collection for Lab Analysis (Field Sheet - Section 7)
If the source of water is obvious, or can be quickly traced upstream, then collection
of samples may not be required. Sometimes however, additional laboratory
analytical tests help with source identification.
The most cost-effective approach is to use the municipal laboratory, Water
Treatment Plant or Wastewater Treatment Plant, wherever possible. Contracted
laboratory services for additional parameters can be used where needed.
If the outfall has dry weather flow, samples can be collected for laboratory analysis.
■ Fluoride, if city water is suspected, such as in a waterline leak
■ Total Coliform, E-coli, or Enterococci if sewage is suspected
■ Detergents if washwater is suspected
■ Others as determined
Laboratory Sample Collection
a. Put on sampling gloves
b. Do not touch the inside of the cap or bottle
C. Sample the discharge directly into the appropriate sample bottle
d. If a dipper or bucket is needed to collect the sample, be sure to condition
the collection container by rinsing it with the sample water before use.
e. Do not discard or spill the preservative in pre -preserved sample bottles
f. Label bottles with outfall number, time, and date
g. Complete the Chain -of -Custody
h. Place bottles in the cooler with ice
i. Deliver to the lab, or call lab for a sample pickup
All samples collected for lab analysis must be preserved as specified by the lab for
the specific parameters being analyzed. Refer to the Standard Methods for the
Examination of Water and Wastewater for more information about sample
collection and sample preservation: http://www.standardmethods.org/. Note that
E-coli Bacteria samples must be processed within 6 hours of collection. For this
reason, prior arrangements should be made with the lab, and sampling on Fridays
and the day before holidays must be avoided.
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7. Non -Illicit Discharge Concerns (Field Sheet - Section 8)
Make a note of any concerns such as trash, needed infrastructure repairs, flows
from upstream sand filters or other stormwater control measures, sheen in upstream
catch basins, suspect natural decay, possible bacteria, and decisions to return for
additional testing.
SOURCE IDENTIFICATION
A dry weather flow may be groundwater, leaking drinking water, or an illicit discharge or
connection. If the flow can be easily and quickly traced to the source in the field through
visual observations at the time that the flow is observed, this is the preferred method of
assessment. Further investigation may be required.
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Attachment I
OUTFALL RECONNUSSANcri, IN-%7E;NTORY/ SAAEMLE COLLEcTioN REILD SHEET
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+C:IutBkIID Revannaissance Pm.v emla!tT Field Sheet
Se
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ection 4- Pln aa3 cal Indicators
�n d iy cs rar Flowwnn dg Ontfalls Only
nnn t1h. fl-7 r l '4— h -"Ta �Ijf V" .C'"'dean ft: ;crrtireaa a➢
INDICATOR
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Section 9. I hy3ical Indicators lnrd Both Flowing and Non-FIGww=ing Outfalls
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Section 7- Data Collection
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