7. NCS000465_SOP Dry Weather Flow Monitoring & Detection_20210310

Morrisville
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STORMWATER PROGRAM STANDARD OPERATING PROCEDURE (SOP)
Dry Weather Flow Monitoring,&, Detection
Date: January 25, 2019
To: Town Departments & Public
Prepared By: Tony Victor, Environmental Specialist
Approved By: Joshua Baird, Stormwater Engineering Manager
Purpose:
The primary objective is to detect and eliminate illicit discharge by observation of dry weather
discharges into SCMs, at major outfalls, and from any source. Reporting and rehabilitation are
essential to a successful stormwater program by identifying and eliminating them along with
remediation of pollution damage.
Details:
♦ Stormwater Staff will patrol areas of Morrisville 72 or more hours after a rain event in order to
detect areas of dry weather flows or potential illicit discharge and will respond to concerns
regarding dry weather flows or potential illicit discharge communicated by consumers.
• Stormwater Staff will utilize water quality monitoring devices and protocol at outfall areas 72
or more hours after a rain event in order to detect areas of potential illicit discharge.
• Should an area (outfall, dumpster, SCM, etc.) be identified as having or potentially having illicit
discharge during monitoring, future observation of the identified area will then occur at higher
frequency.
• When an illicit discharge is confirmed, Stormwater Staff will immediately act to minimize the
impact of the illicit discharge on the Stormwater conveyance. Stormwater Staff will also
immediately contact the property owner regarding responsibility for ceasing the discharge and
remediation of the impact.
• Following the immediate response to the illicit discharge, Stormwater Staff will follow the
Notice of Violation procedures and document the event in the Access Database as appropriate.
♦ Stormwater Staff will monitor efforts to ensure the illicit discharge is completely ceased and
that appropriate remediation efforts are employed by the responsible party and completed in a
satisfactory manner.

Oualitative Observations
Qualitative observations will be documented on the Survey 123 App, on the Access Database, in the
specified folder on the K: drive. Field observations made during each visit for all categories of
discharge include the following are documented on the Survey 123 App for outfalls, on the Access
Database Concern Tracking Form for all illicit discharges investigated.
Flow Measurements
Discharge samples are to be monitored by observation and, if possible, samples taken with YSI Pro
Plus Multi Parameter monitoring equipment.
Initiate Investigation:
• Notify the appropriate authorities.
• Notify the property owner.
Describe actions and directions
• Provide technical assistance for removing the source of the discharge or otherwise
eliminating the discharge.
Describe assistance that might be available.
• Fill out a Concern Tracking Form in the Access Database covering the following items:
Date Town became aware of the illicit discharge
Date the Town initiated an investigation of the discharge
Date the discharge was observed
Location of the discharge
Description of the discharge
Method of discovery
Date and method of removal/remediation completion and verification
Enforcement actions
Fully document any analytical monitoring utilized including decision process to utilize
analytical monitoring
• Initiate and complete the Notice of Violation process.
• Assess Civil penalties as per the Town of Morrisville Unified Development Ordinance
• Provide follow up inspections at more frequent intervals
Communication and Correspondence:
• Stormwater Staff will communicate with all responsible parties and contractors.
• Stormwater Staff will report to the proper authorities all reportable quantities, contamination
levels, enforcement actions, remediation efforts and results with documentation.
Employee Training_
• Training is to be provided to all appropriate municipal staff, who as part of their normal job
responsibilities, may come into contact with or otherwise observe an illicit discharge or illicit
connection.
Records:
• All sampling data collected, correspondence, responsible parties, cleanup/environmental
remediation efforts and reports are to be retained in the public records.