McInnis, Amanda, McInnis

Amanda McInnis is a project manger at Jacobs and has more than 25 years of experience in the wastewater engineering field. She has civil engineering...

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About McInnis, Amanda

Amanda McInnis is a project manger at Jacobs and has more than 25 years of experience in the wastewater engineering field. She has civil engineering degrees from the Univeristy of Wisconsin and the University of Washington. She has three children and currently lives in Missoula, Montana.

McInnis, Amanda

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Description: Developing An Alternative To A Point Source Based Approach To Regulating Nutrients...

Developing An Alternative To A Point Source Based Approach To Regulating Nutrients In Puget Sound

Abstract

The Puget Sound (Sound) region has faced increasing pressures from growth and development. Increases in nitrogen in the Sound can result in increased phytoplankton and algae growth. This growth is also influenced by other variables like temperature and light and can result in drops in dissolved oxygen (DO) in spring to fall when surface waters heat up and thermal stratification of water isolates bottom water from atmospheric replenishment of oxygen. The Salish Sea Model (SSM) was developed by Pacific Northwest National Labs to simulate these complex interactions. The State of Washington Department of Ecology (Ecology) has a marine oxygen standard limiting human caused depletion to more than 0.2 mg/L. The threshold of hypoxia is generally set at 2.0 mg/L DO. Target DO standards are much higher with 4.0 mg/L fair, 5.0 mg/L good, 6.0 mg/L excellent, and 7.0 mg/L extraordinary. The SSM indicates that low DO is most concerning in shallow bays with poor circulation, which is consistent with monitoring data. This effect is most pronounced in the late summer and early fall because of thermal and salinity stratification. While the depressed DO levels are largely due to natural factors, it is important to consider that anthropogenic influences. Like other estuarine 'dead zones' the Puget Sound exemplifies a fjord issue that is increasingly common. Sills prevent circulation of deep water with oxygen-rich tidal exchanges. Distal zones of the fjord do not mix with pelagic waters. Water age below the thermo/halocline, or in stagnant shallow areas, allows for depletion of DO without because there is no replenishment from mixing with oxygen-rich waters. Hence the formation of anoxia, hypoxia, or depletion of DO below key habitat suitability thresholds.
A fundamental problem within these systems is that DO deficits tend to persist despite nutrient reductions because of positive feedbacks . This is well documented in other areas such as the Chesapeake Bay and the Baltic Sea. There is no evidence that the Puget Sound has a different DO dynamic. Thus, the findings of the SSM model need to be placed within this larger context. Ecology issued a report that reviewed the results of the SSM in January 2019. Using the SSM, Ecology mapped the modeled duration and extent of the dissolved oxygen depletion and examined the impacts from the wastewater treatment plants. While Ecology was pursuing the modeling and technical work to characterize DO impairment, Northwest Environment Advocates (NWEA) filed a petition with Ecology in November of 2018 to accelerate regulation of point source discharges in Thurston County Superior Court. The petition was denied. In response to the petition and court case, Ecology moved forward with the nutrient program. From 2020 to 2021, Ecology conducted a nutrient working group to develop a general permit to regulate municipal wastewater discharges into the Sound. The working group could not reach consensus on the best pathway forward to address this issue. Nevertheless, Ecology developed a draft permit, issued in September 2021, that focuses on municipal plants and requires optimization studies in the near term and plans to reduce municipal effluent discharges to 8 mg/L or 3 mg/L total nitrogen in the long term. The program will cost more than $10 billion to implement in capital alone with a projected benefit of 50% improvement in modeled days of DO depletion.
The following will present the work to date in developing science to define the impairment of the Sound and the current draft of the Permit. More importantly, it will propose complimentary pathways that achieve water quality improvements in a shorter timeframe, include realistic timeframes and represents responsible stewardship of the investment from the Utilities' rate payers.
The Puget Sound dischargers have maintained the Utility Caucus group that was formed as part of Ecology's nutrient work group. This group is tasked with advocating for their mutual interests and interested in developing alternative approaches to improve water quality in the Sound. About 5 million people in Puget Sound are served by the municipalities that make up the Caucus. They expect responsible stewardship and protection based on well-developed science that produces measurable benefits. These utility stakeholders have considered development of alternative approaches to addressing water quality concerns in the Sound as alternatives to the current point source based approach.
Improved data collection/modeling of the bays. The SSM is a large-scale model that is not accurate enough to detect changes in DO at the 0.2 mg/L level. Smaller scale models and/or data gathering to review critical bays and localized impacts may improve model accuracy at the bay level and allow testing of alternative management approaches to address concerns related to nitrogen and DO. For example, non-point source controls, interventions like oxygenation, or MS4 management actions could be weighted against the proposed point source actions for each bay.
Integrated Planning: Ecology's General Permit approach focuses solely on point source municipal wastewater outfalls and as a result, misses many of the larger water quality issues and influences in Sound. In 2019, integrated planning was codified in the Clean Water Act as a regulatory approach supported by EPA. Integrated plans offer the opportunity to view a watershed from a wider view (outside of a single outfall) and develop an action plan that improves water quality overall. The plan can include wastewater, stormwater, green infrastructure, non-point source control, source water protection, asset management and reuse. The integrated approach is a voluntary approach that lends itself to adaptive approaches that include feedback water quality loops.
Adaptive Management: Adaptive management is an iterative process to work towards water quality improvements. It begins when initial changes are made in a receiving water (load reduction, habitat modification, other BMPs) and then the environmental response is evaluated to guide decision making about the next step. In essence, adaptive management is learning by doing and using improved data and information over time to improve decision making with the intent of achieving a goal within a specified timeframe. This approach makes sense in the Sound where there are many stakeholders that are interested in improving the Sound, have available resources and staff and are willing to engage in a collaborative process that can make positive change.
Oxygenation: Supplying pure oxygen to the water directly addresses the water quality impairment and the associated environmental degradation. Oxygen is distributed in the water column in strategic locations using fine-bubble diffusers designed to raise dissolved oxygen levels without disturbing thermal or salinity stratification. The oxygen rich water then circulates throughout the impaired water body via natural currents. The stakeholders will work toward development of a comprehensive menu of both natural and engineering options for managing nutrients. These results will assist with providing a roadmap for the future.

To reduce nitrogen loading and oxygen depletion in the Puget Sound, the Washington Department of Ecology issued a general nutrient permit to 58 municipal wastewater dischargers on the Sound. The Puget Sound Nutrient General Permit represents one solution to decreasing oxygen levels; reducing loads from municipal wastewater treatment plants. A broader multi-faceted solution may be required to measurably improve water quality in the shallow bay areas.

SpeakerMcInnis, Amanda

Presentation time

11:00:00

11:15:00

Session time

10:30:00

12:00:00

TopicIntermediate Level, Nutrients, Watershed Management, Water Quality, and Groundwater

Author(s)

McInnis, Amanda

Author(s)Amanda McInnis1; David Austin2; Ryan Dunne3

Author affiliation(s)Jacobs Engineering Group, Missoula, MT1; Jacobs Engineering Group, Mendota Heights, MN2; Jacobs Engineering Group, Seattle, WA2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158564

Volume / Issue

Content sourceWEFTEC

Word count16

Puget Sound Point Source Regional Cost and Rate Study Summary

Abstract

The Washington State Department of Ecology's (Ecology) Puget Sound Nutrient General Permit (PSNGP) regulates total inorganic nitrogen (TIN) loadings from municipal point source wastewater treatment plants (WWTPs) to Puget Sound. The permit requires all 58 PSNGP utilities to produce both optimization studies and to complete a nutrient reduction evaluation (NRE) where applicable, similar to a facilities plan. The PSNGP also requires review of treatment needs to all known and reasonable technology (AKART) annually, and to 3 mg/L in the summer (for dominant and moderate dischargers only). In 2022, the Association of Washington Cities (AWC) was awarded an Ecology grant to complete a prepare optimization studies and NREs for submission to the Ecology. Twenty nine of the 58 utilities participated in the study. The study was completed in December of 2023. In PSNGP, each facility is categorized based on TIN load: dominant (D), moderate(M), and small (S). Figure 1 shows PSNGP regulated utilities. As directed in the legislative proviso that appropriated the grant funding, only small and moderate WWTP dischargers were eligible for the technical assistance project. Table 1 shows total PSNGP and participating dischargers. The PSNGP requires dischargers to evaluate operational strategies for maximizing nitrogen removal and summarize results in an optimization study (NOP). Common optimization strategies included additional process monitoring and control adjustments, and replacement/upgrade of small-scale equipment. All moderate and dominant dischargers were required to submit NOPs to Ecology by March 31, 2023. Table 2 shows an estimated cost of the selected optimization strategies. Estimated optimization costs and performance from all moderate and dominant NOPs, including non-study participants averaged $300,000 for moderate dischargers and $25,000 for small dischargers. Optimization costs for moderate dischargers were estimated to be $0.10 to $15 per pound whereas costs to attain AKART upgrades were estimated to be $18 to $27 per pound. Dominant and moderate dischargers with existing average annual effluent TIN concentrations >10 milligrams per liter (mg/L) are required to prepare an NRE. For the AWC project participants, the PSNGP requires alternatives assessment to meet two levels of effluent TIN:

* AKART, 8 to 10 mg/L of TIN; and

* 3 mg/L of TIN (or equivalent load) as a seasonal (April through October) average The PSNGP calls for preparation of an NRE that considers costs for all known and reasonable technology upgrades (defined as 8-10 mg/L for most facilities) for dominant, moderate, and small dischargers and 3 mg/L TIN seasonally (April through October) for dominant, and moderate dischargers. Estimated capital, operation and maintenance, and net present values costs to for the AKART and 3 mg/L WWTP upgrades were determined if they were constructed today and operated for 20 years. Estimated capital and operating compliance costs for project participants are determined (NRE/AKART documents are not due until the end of 2025, so nonparticipant data is not available). The costs calculated are only associated with the nitrogen reduction upgrades to meet the requirements of the PSNGP and do not include any other utility expenses beyond what is reflected in the current rates (replacement costs due to aging infrastructure, inflation adjustments, etc.). Table 3 summarizes the estimated treatment costs for AKART and reaching 3 mg/L (or equivalent load) level of nitrogen reduction. Costs for moderate dischargers were higher than small dischargers ($10M to $35M compared to $6M to $17M), with higher costs for moderate dischargers to treat to 3 mg/L TIN ($16-$49M). Cost per pound of TIN removal for small dischargers were much higher than moderate dischargers ($18 to 27/lb for moderate dischargers as compared to $580 to $1100 per pound for small dischargers). Table 4 shows the total estimated net present value (NPV) cost per household for small and moderate participants (includes capital and operational costs) for the AKART and 3 mg/L treatment levels. Figures 2 and 3 summarize a customer's annual wastewater bill as a percentage of household income. By EPA metrics, rate impacts are considered low if annual sewer bills are less than 1 percent of household income, midrange if bills are 1 to 2 percent of household income, and high if annual sewer bills are greater than 2 percent of household income. The affordability analysis uses two metrics: the residential indicator (RI), which is based on median household income, and the lowest quintile residential indicator (LQRI). Over half of the utilities would see rates increase at least 50% with some rates more than doubling. Compliance with the new PSNGP would increase rates to a medium or high impact level on most households at median incomes and would have a medium or high impact on all households with the lowest quintile incomes. This study shows significant PSNGP compliance costs for moderate and small dischargers to the Sound with rate impacts hitting both median and lowest quintile income household in a meaningful way. In addition, there are environmental consequences for this action in the form of increased power consumption, production and trucking for chemicals and nitrous oxide emissions for nearly all of the Puget Sound plants that have not yet been weighed against the benefits of reduced TIN to the sound.

This study shows significant Puget Sound Nutrient General Permit compliance costs for moderate and small dischargers with rate impacts affecting both median and lowest quintile income households in a meaningful way. For dischargers participating in the study, more than half dischargers would have a rate increase above 50%, with rates escalating more than 200% for some dischargers.

SpeakerMcInnis, Amanda

Presentation time

14:00:00

14:20:00

Session time

13:30:00

15:00:00

SessionNavigating Nutrient Dynamics: Modeling for Water Quality Excellence

Session number217

Session locationRoom 256

TopicNutrients, Stormwater and Green Infrastructure, Watershed Management, Water Quality, and Groundwater

Author(s)

McInnis, Amanda, Jagini, Shruti

Author(s)A.B. McInnis1, S. Jagini2

Author affiliation(s)1Jacobs, MT, 2Jacobs, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159584

Volume / Issue

Content sourceWEFTEC

Word count11

Base text size -

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