pitfalls of traditional approaches to wet weather collection … · 2019-05-15 · onventional...

Pitfalls of Traditional Approaches to Wet

Weather Collection System Management &

How McKim & Creed Can Help You Weather the Storm

MCKIM & CREED | Pitfalls of Traditional Approaches to Wet Weather Collection System Management & 2How McKim & Creed Can Help You Weather the Storm

PITFALLS OF TRADITIONAL APPROACHES TO WET WEATHER COLLECTION SYSTEM MANAGEMENT &

HOW MCKIM & CREED CAN HELP YOU WEATHER THE STORM

Conventional sanitary sewer evaluation and survey (SSES), and replacement and renewal (R&R) techniques are steeped in tradition. Unfortunately, these approaches to

wet weather collection system management have a long track record that has just as many success stories as failures. We know this to be true because all sewer systems still experience some level of wet weather flow management issues, even since the EPA’s introduction of SSES programs in 1975.

THE HISTORY OF SSES SSES was the brainchild of the EPA. In 1975, the agency published the “Handbook for Sewer System Evaluation and Rehabilitation.” This was effectively the engineering industry’s first foray into the wet weather issues (inflow and infiltration [I&I]) that were beginning to pop up around the country.

After the initial 1975 publication, the EPA and industry rode the coattails of what became the SSES movement. With very little change in the methodology or technology, the EPA SSES document ruled the land until, in 1991, the EPA published a new guidance document titled "Sewer System Infrastructure Analysis and Rehabilitation." This document did not introduce any vastly different evaluation techniques, but did elaborate on technological advancements in various rehabilitation methodologies such as fold and form and cured-in-place lining. This introduced the "renewal" aspect of modern R&R.

In 1994, the EPA issued the Combined Sewer Overflows (CSO) Control Policy. The policy established a consistent, national approach to controlling CSO discharges into national waters through the National Pollutant Discharge Elimination System (NPDES) permit program. The following year the EPA published the “Combined Sewer Overflows (CSO) Guidance for Long-Term Control Plan.” The purpose of this plan was to facilitate implementation of the CSO Control Policy and help guide municipalities in developing long-term control plans for site-specific CSOs. This was the first document from the EPA that introduced modeling into both sewer systems and receiving water quality. The introduction of the modeling component started the engineering industry down the road of using computers to effectively analyze and characterize both combined and separate sewer systems. This document kept the focus primarily on CSOs until 2001, when the EPA proposed the Sanitary Sewer Overflow (SSO) Rule.

The 2001 Proposed EPA Rule on SSOs was the basis for the 2004 report to Congress on control of CSOs and SSOs. This report stressed the impact SSOs were having on water quality.

This revelation led the EPA to develop the “Guide for Evaluating Capacity, Management, Operation, and Maintenance Programs at Sanitary Sewer Collection Systems” (CMOM). This document reiterated proper collection system management and bookkeeping with little focus on wet weather issues. At this point, I&I evaluation methodologies such as night time flow isolation, dye testing, smoke testing and flow monitoring remained unchanged from the 1975 publication.

Many of the problems addressed in that document stemmed from Hurricane Agnes which, in 1972, impacted the entire East Coast and was the basis of the Clean Water Act.

It also seemed to note that a large portion of the SSOs were a function of poor operation and maintenance practices as well as wet weather.


THIS HAS CREATED A PITFALL OF PROBLEMS FOR MUNICIPALITIES SUCH AS:

1 Improper focus of limited financial resources

2 Lack of quantitative projected results

3 Unrealistic I&I reduction assumptions and expectations

4 Continued operational challenges after I&I reduction projects

5 Costly rehab alternatives that result in higher wet weather peak flows

6 Disconnection between phases and/or basins

7 Proprietary data that can’t or won’t be shared

8 Poor flow monitoring data due to sewer configuration/condition

9 Improper use of design storms

10 No measurable progress made toward flow reduction or excuses

11 No long-term baseline for future evaluation

For too long, the engineering industry has completed I&I investigation in some fashion, then completed some level of monitoring, then force fit a model after spending millions on renewal and replacement strategies in the hopes of I&I reduction during wet weather. Municipalities are rarely

presented quantitative operational goals based on modeling alternatives such as peak flows at the plant that are based on a reduction percentage of I&I, or wet weather storage at a key location that would resolve conveyance issues without upsizing downstream pipes, pump stations, and plants.

THE CURRENT SITUATION


1 Asset Mapping and Connectivity

This sounds simple but is often one of the most difficult tasks. Maps are field verified (unless done previously) because all future phases, including flow monitoring and modeling, depend heavily on accurate drainage basins. If mapping is not accurate, then all future results are inaccurate, or force fit.

McKim & Creed has been ranked by Engineering News-Record as the #1 Surveying and Mapping Firm in the Southeast.

Manhole Inspection – This step is part of asset mapping and connectivity. It warrants additional mention because it entails collecting data on condition, depth and other parameters that affect connectivity, flow metering and modeling.

McKim & Creed uses the latest CleverScan technology and pole cameras to georeference data.

McKim & Creed's approach to managing wet weather issues is founded on quantitative operational goals that are based on sound modeling alternatives.

Our procedures are consistent with the EPA's Peak Flows Management Rule, which opened to comments in April 2018. By integrating rainfall independent I&I (RDII) investigative techniques, flow monitoring, modeling and replacement technologies with quantitative measures, municipalicities can

MCKIM & CREED'S APPROACH TO MANAGING WET WEATHER COLLECTION SYSTEMS

realistically manage I&I removal rates, reduce SSOs and optimize wastewater treatment operations.

McKim & Creed offers the entire suite of tools—in-house— to guide our clients from SSES to modeling, capital plan development and, ultimately, construction.

In our 25+ years of experience in resolving wet weather issues, we have developed the following steps that lead to successful project delivery:


3Subsurface Utilities Engineering/Cleaning

Dirty or collapsed pipes don’t reflect full capacity, so cleaning may be necessary to arrive at more accurate flow monitoring and modeling results.

McKim & Creed owns and operates vacuum and jetting equipment as well as all sizes of cleaning equipment.

2 CCTV Services

Most firms complete CCTV services after I&I investigation and flow metering. However, past experience has shown that assumed pipe conditions may be false and collapsed pipes may affect flow metering and modeling results. If these conditions are known, they can be compensated for in metering and modeling efforts without having to make repairs.

McKim & Creed's CCTV services provide a full, 360-degree interior view of aging infrastructure. And because the technology provides the best imagery at higher production rates, your dollars can be spent fixing your aging infrastructure issues, rather than simply studying the problem.


5Instrumentation and Controls

A thorough understanding of data formats and logging capabilities is needed to coordinate flow meters and SCADA-generated data. For example, in some instances a pump mag meter may only record daily totals; therefore, the pump rates can’t be used to document the peak flows required for modeling efforts. Our I&C group can handle all programming and even build additional SCADA components if required.

McKim & Creed's in-house I&C professionals can integrate plant SCADA systems with the flow monitoring program to aid in wet weather plant operation.

4 Flow Monitoring

All too often, flow monitors are placed to quantify I&I but not to validate and calibrate modeling. McKim & Creed's meter placement will serve both purposes and capture all flows, including potential overflow locations.

McKim & Creed has completed more than 100 open channel flow meters and 45,000 meter months of data analysis. We can meter even the most challenging sites effectively and efficiently while offering real-time, web-based access to data.


7RDII Analysis

Our standardized approach to RDII allows for R values (% of rain getting in the sewer) to be compared across basins of any size. R values have

three different types of values: short-term (inflow), medium (runoff) and long-term (infiltration). With this information, we can then rank and prioritize I&I investigation techniques based upon the type of I&I suspected.

McKim & Creed team members were part of the beta testing group invited by the EPA to evaluate and comment on the SSOAP software. This software is used to standardize the approach to analyze flow monitoring data.

8Asset-Based Dye Testing Dye testing is a way to find direct inflow from roofs, catch basins and other areas where smoke testing may not work because of traps in the pipe. These results are georeferenced to pipe segments or properties, depending on which asset our client prefers.

McKim & Creed's use of advanced technologies makes the company a front runner in cloud-based data collection.

6 Hydraulic and Hydrologic Modeling

McKim & Creed models are based on the data collected in steps 1-5 and are calibrated to multiple storm events. This ensures our model can perform accurately over various seasons and differing ground water conditions.

McKim & Creed team members are routinely selected to share modeling success stories at national and state technical conferences.


9 Asset-BasedSmoke Testing

Asset-based smoke testing uncovers I&I issues in roofs, pipe defects, catch basins and other large areas. Results are georeferenced to pipe segments or properties, depending on which asset the client prefers.

McKim & Creed uses smart technology to georeference all defects collected, and includes pictures of defects in the database.

10 NightTime Flow Isolation

This method originated in 1975 and is still valid today. Nighttime flow allows us to take the dye, smoke, and CCTV data and quantify more precisely the exact volume of water infiltrating the pipe. These results are georeferenced to pipe segments.

Results are verified and documented with pictures and loaded into the database for cross reference into the model.


11 Alternative Analysis and Capital Plan Development

McKim & Creed understands that, for successful wet weather issue management, collected data must be transformed into a plan of action. No one plan will eliminate all overflow because of the varied weather patterns and hurricanes in the region; however, we work with our clients to develop plans that meet regulatory expectations but don't over-promise on system performance during wet weather.

McKim & Creed has developed Capital Plans featuring more than $200 million of wet weather management solutions.

12Rehabilitation Design

When done as part of an overall wet weather mitigation process, rehabilitation design can be a cost-effective way to improve collection system operation. Rehabilitation can also be an expensive way to negligibly reduce I&I if goals are not properly managed. McKim & Creed manages designs to achieve the goals of the Capital Plan and reduce wasteful spending.

Since 2014, McKim & Creed has been ranked one of the Top 50 Trenchless Design Firms in the U.S. by Trenchless Technology magazine.


13 Wastewater Process and Optimization

Ultimately, wet weather flow must be treated. Why? Because no collection system rehabilitation program can remove all I&I. McKim & Creed works with our clients to optimize the wet weather operation of their system and maximize conveyance, storage and treatment. Our I&C group can work in real-time, wet weather controls based on key system parameters from flow meters or sensors such as rain gauges.

McKim & Creed has won dozens of state and national awards for wastewater design and optimization.

14Design-Build

Once all the data is in, the Capital Plan is adopted, and the design is complete, then it is time to build the improvements and achieve the goals set forth. McKim & Creed employs the most effective and efficient delivery system for the project, including alternative systems such as design-build.

McKim & Creed has received awards from state DBIA chapters for our design-build projects.


MCKIM & CREED | Pitfalls of Traditional Approaches to Wet Weather Collection System Management & 11How McKim and Creed Can Help You Weather the Storm

McKim & Creed is uniquely qualified to perform and manage all the services needed to resolve wet weather issues in a comprehensive fashion. More importantly, we help our clients understand the quantitative impacts their financial resources will have on plant and system flow.

At the end of the day, it is important to know your system's strengths and weaknesses. It is also important to manage expectations of your system's performance in ever-changing weather patterns. McKim & Creed can help you weather the storm.

For more information, contact Ken Orie, PE, PACP, 919.233.8091, [email protected]

15 construction administration and observation

If a more traditional method of bidding and construction is required, then McKim & Creed has CA/CO capability that will carry the design through construction.

McKim & Creed offers full- and part-time observation, as well as bidding assistance and construction administration services

pitfalls of traditional approaches to wet weather collection … · 2019-05-15 · onventional...

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