The City of Meridian owns and operates a Public Wastewater Treatment Plant and a Sanitary Sewer Collection System under the rules of the Idaho Division of Environmental Quality (IDEQ) and under a permit issued by Region X of the U.S. Environmental Protection Agency (USEPA). The rules and permit dictate levels of performance for the operations of both the Treatment Plant and the Collection System. These rules for the Collection System Operation are basically defined as the duty to maintain.
Ownership and Operation
The City of Meridian owns and operates a collection system under the following rules, permits, and ordinances:
NPEDS Permit: the City of Meridian currently operates a Wastewater Treatment Plant and Collection System under US EPA Permit Number ID-002019-2.
City Code, Chapter 4, SEWER USE AND SERVICE: Within the code, the organization of the City’s system is defined and the City is to maintain the system at all times so that sewage is efficiently and sanitarily carried from uses to the sewer treatment plant.
Wastewater Pretreatment Ordinance No. 01-906: This ordinance further defines users of the collection system under the overall heading of Industrial Users. In addition, prohibited discharges are defined.
State Licensing of Operators: Licensing authority for water and wastewater operators is accomplished through the Idaho Bureau of Occupational Licenses. The collection system is defined from Class I to IV, and a responsible charge operator to the level of the system is required.
The City of Meridian operates a gravity collection system of approximately 500 miles in length. Piping sizes range from 8-inch to 36-inch. In addition the City’s system has pressure lines and lift or pump stations. The combined piping length is over three million linear feet of piping. There are in the range of nearly 10,000 manholes. The current collection system planning boundary encompasses approximately 70 square miles.
The existing sanitary sewer collection system is the most expensive infrastructure element that the City of Meridian owns. The replacement value for the system is in the range of $480,000,000.
City gravity collection system lines are cleaned on a rotation basis. The City has ongoing inspection activities that allow determination of condition of the gravity collection system and procedures to report the condition, including recommended corrective action. Areas noted to be deteriorated are identified by CCTV reviews and by the ongoing cleaning activities.
During routine line cleaning any deteriorated manholes noted are reported. A manhole inspection program has also been developed.
The City maintains various lift stations. Their function is to move (lift) sewage from lower areas of the collection system to gravity lines to the treatment plant. Weekly (2-3/ week) there is on-site observation of each lift/pump station. A lift/pump station inspection checklist has been developed. All lift/pump stations either have standby power at the site or the City has available portable power units to use upon a power outage.
Collection System Inflow and Infiltration:
The City of Meridian regularly conducts I and I analyses, generally for system flow modeling. The engineering evaluation of pipe deficiencies is conducted by the Public Works Department with the support of the collection group. In summary, the City has in place a procedure to monitor I and I and evaluate the conditions in the system and determine when corrective action is necessary.
The City of Meridian conducted an odor study on the collection system. The results of the study indicated that currently odor is not a significant problem. However, it was noted that in the future that some type of odor control will need to be added to the collection system – either chemical addition spot application (at the point of the problem), or some type of vacuum driven scrubber system to control drafting and provide a wider area of coverage.
Smoke testing is not done on a regular basis. A smoke testing program is under development for areas of the City that has been constructed earlier than 15 years ago and in areas of high seasonal sub water.
Dye testing is only done to investigate problems. Dye testing is a tool specific to determine the existence or non existence of connections on an individual basis.
City Collection system lines are routinely cleaned. Areas identified to have root intrusion are cleared of roots.
Currently existing City gravity collection system lines are televised on a rotation basis.
Maintenance Activity Logging:
The City’s data is maintained on the City’s Hansen Infrastructure Management System. (System upgrade scheduled for 2009). Routine maintenance activities are scheduled, completed, and recorded using the system.
Use of Contractors:
In 2009 the City purchased the necessary equipment to perform sewer line cleaning and CCTV line inspections that were previously conducted by contractors.
The City will continue to sub-contract out specialty projects.
A program for responding to overflows and providing emergency operations has been developed, (Sanitary Sewer Overflow Response Plan).
A program to maintain maps of the collection
system is implemented through the Public Works Engineering Department. The
Geographical Information System (GIS) section creates and maintains all the
maps used by City customers and field crews. Field crews use printed maps from
the GIS to assist in performing the scheduled and unscheduled repairs on the
Inspection and Approval Process
The normal process for project review, inspection, and acceptance by the City is through Public Works. Upon final acceptance all line testing is verified and final CCTV work is completed. In addition, all manholes are vacuum tested. All testing is done in accordance with the Idaho Standards for Public Works (ISPWC) specifications.
City Staff - Training
The City has a training budget available for personnel. Generally, all collection system personnel are trained on the use of the hydro-cleaner, self-contained breathing apparatus, service truck with crane, safety equipment including confined entry, and portable generator sets.
The City has an internal safety committee in Public Works that conducts safety training and awareness meetings. The City provides a safety manual for all personnel with ongoing reviews. The Treatment Plant also conducts an in-house Safety Program and has an active in-house Safety Committee.