Philadelphia Water Department

This study demonstrates a data driven method for estimating fifth-liter water lead levels from first-liter water lead data.

Data from Pacific Northwest National Laboratory’s conversion hydrothermal liquefaction (HTL) program for wet waste was used to update the pathway techno-economic analysis (TEA) for the fiscal year 2020 State of Technology (2020 SOT). The modeled fuel blendstock MFSP for the 2020 SOT is estimated at $4.50/GGE (with ammonia stripping of the AP), a reduction of $0.61/GGE, or 12%, relative to the 2019 SOT (Snowden-Swan et al. 2020). Progress in the HTL area includes increased reactor LHSV from 3.6 to 4.0 and a newly designed staged approach for the sludge pumping and heating, resulting in a 1 cent and 26 cent reduction in modeled MFSP, respectively. The newly designed heat exchanger configuration is less material and capital intensive than the previous SOT, and provides a system design that is more scalable with regard to practical fabrication limitations. Further improvements may be possible with the use of core inserts to enhance tube velocity and heat transfer rates. Biocrude hydrotreating research progress improved weight hourly space velocity (WHSV) from 0.67 to 0.72 hr-1 in the guard bed and from 0.39 to 1.02 hr-1 in the main hydrotreating bed, a 7% and 162% improvement, respectively. Hydrotreating performance was not sacrificed at the higher throughput rates and catalyst activity remained stable over the run. The demonstrated increase in WHSVs reduced the modeled MFSP by $0.34/GGE.

The city of Philadelphia invests in the renewal of its wastewater and combined sewers to keep the collection system functioning effectively and efficiently. Scenarios that lead to replacement of collection system pipes include pipe failure, capacity limitations, end of design life, etc. In this paper, we describe an ongoing effort to evaluate sewer design peak flow capacity for Philadelphia Water Department’s (PWD) sewer system. Historically, capacity analyses were conducted using record-drawings, measurements, and manual hydrologic and hydraulic calculations. The updated approach described here utilizes a systematic and semi-automated approach to assess sewer capacity. Along with traditional engineering calculations, tools such as geographic information systems (GIS), computer models, and databases are used to implement the updated approach. The process is not fully automated and human intervention is required. We demonstrate the potential of the collection system capacity inventory to support capital planning through investment modeling, and to assist with engineering design. For example, the citywide database of flow capacity can expedite development and analysis of complex hydrologic and hydraulic models. The hydrologic and hydraulic models developed could be then used for evaluating alternatives to meet defined objectives.

Statistically downscaled global climate model (GCM) precipitation output is available for Philadelphia, but the temporal resolution is too low for direct use in model-based urban stormwater applications. Additionally, GCM output for Philadelphia does not accurately represent local storm intensities and durations. To address these limitations, this study presents an innovative approach employed by the Philadelphia Water Department (PWD) to transform GCM output into actionable science that can directly inform planning, design, and engineering applications, including hydrologic and hydraulic (H&H) modeling and intensity-duration-frequency curve development. This approach uses GCM output for current (1995–2015) and future (2080–2100) conditions under a certain greenhouse gas emission trajectory to develop delta change factors based on season and storm size. These factors are then used to create a plausible future hourly time series. A stochastic generator was also developed that utilizes the adjusted future time series to explore potential variability in projected precipitation patterns. The approach presented in this study is practical and transferable, addressing the need for actionable climate change information in the field of water resource management.

Historical Lead and Copper Rule (LCR) regulatory sampling data from the Philadelphia Water Department were examined to explore their potential value for guiding a water utility's progress with regard to optimal corrosion control treatment (OCCT). If a system has established a stable water treatment process with consistent corrosion control treatment (CCT) and has achieved continued decreases in lead levels during regulatory sampling, then the information collected during LCR monitoring can be used as an important data set of a broader OCCT evaluation and will help inform the benefit of additional changes in CCT. Since water utilities have LCR data dating back to 1992, these data should be used to make informed decisions. This research also showed that the addition of orthophosphate has resulted in a significant decrease in lead levels at the customer tap. Additionally, profile sampling was performed to show that first‐draw 1 L samples following a 6 h stagnation period provide a good representation of the lead concentrations measured from lead service line and home plumbing samples at the same sites and may be used to indicate overall changes in lead concentrations at the tap resulting from CCT for this system.

Philadelphia Water's Green City, Clean Waters program outlines a vision for large-scale implementation of green stormwater infrastructure (GSI) to reduce stormwater-based demand on the combined sewer system. Stormwater tree trenches are an essential stormwater control measure (SCM) of the Green City, Clean Waters program. In order to effectively assess the performance of stormwater tree trenches, collaborators at Drexel University and Philadelphia Water developed a green infrastructure performance (GIP) model that predicts infiltration rates and estimates water levels within the SCM. Quantitative experimental data are evaluated in order to demonstrate GIP's applicability to a variety of SCMs. 13 SCMs currently monitored by Philadelphia Water are assessed as case studies. Quantitative performance evaluation via simulated runoff tests (SRTs) is discussed. SRT application allows for testing of SCMs in a controlled manner. SRT procedures developed by Philadelphia Water staff are discussed in detail. These procedures introduce metered flow to the SCM via a fire hydrant connection. Quantitative data regarding inflow and water level in the SCM and qualitative observations are collected. These inputs, and precipitation data from natural events, are used to calibrate the GIP model. Analysis protocols and real world applicability are discussed through these case studies. The GIP model uses R and related technologies to execute model routines. R is used to perform quality assurance and quality control of large amounts of data collected in SRT activities. When data analysis and model runs are complete SRT data is used to validate and calibrate additional analysis routines.

Stimulated by the recent USEPA’s green stormwater infrastructure (GSI) guidance and policies, GSI systems have been widely implemented in the municipal area to control the combined sewer overflows (CSOs), also known as low impact development (LID) approaches. To quantitatively evaluate the performance of GSI systems on CSO and urban flooding control, USEPA-Stormwater Management Model (SWMM) model was adopted in this study to simulate the behaviors of GSI systems in a well-developed urban drainage area, PSW45, under different circumstances. The impact of different percentages of stormwater runoff transported from impervious surfaces to the GSI systems on CSO and urban flooding control has also been investigated. Results show that with current buildup, GSI systems in PSW45 have the best performance for low intensity and short duration events on both volume and peak flow reductions, and have the worst performance for high intensity and long duration events. Since the low intensity and short duration events are dominant from a long-term perspective, utilizing GSI systems is considered as an effective measure of CSO control to meet the long-term control strategy for PSW45 watershed. However, GSI systems are not suitable for the flooding control purpose in PSW45 due to the high occurrence possibility of urban flooding during or after high intensity events where GSI systems have relatively poor performance no matter for a short or long duration event.

The climate change adaptation program (CCAP) at the Philadelphia Water Department (PWD) is responsible for identifying the most urgent climate-related risks that the utility will face and adaptation strategies to address these risks. Projections for Philadelphia indicate increasing precipitation, which may pose challenges to the operation and management of PWD systems. In order to understand the risks from increased rainfall, the CCAP is applying representative concentration pathway 8.5 (RCP8.5) global climate model (GCM) projections to local precipitation data for use in hydrologic and hydraulic (H&H) modeling applications. The process of applying GCM projections to system models presents multiple challenges. The spatial and temporal resolution of GCM output is often not high enough for direct use in local H&H models. Additionally, GCM output may not accurately reflect observed regional precipitation patterns, presenting further challenges to directly working with the output. This paper will present the approach that the CCAP took to understand the following: (1) the methods available to downscale GCM output for use in H&H models; (2) the accuracy of GCM simulations in representing local precipitation patterns; and, (3) projected increases in precipitation for Philadelphia considering RCP8.5 output from 9 GCMs and a GCM ensemble. Results indicate that projected increases in precipitation under RCP8.5 are significant. While the GCMs fairly accurately simulate average total precipitation values, the models do not accurately simulate local precipitation characteristics, including the intensity and duration of storm events. This inaccuracy, in combination with the finding that there is no one accepted method to downscale GCM output to resolutions appropriate for H&H modeling, implies that the CCAP would have to develop its own method for applying GCM projections to precipitation time series data.

A recently validated 3-dimensional implementation of the Environmental Fluid Dynamic Code (EFDC) for the tidal-fresh portions of the Delaware Estuary was exercised against the results of a dye release from a sewer outfall during a storm. The influence on dye distribution in the estuary resulting from variations in wind and local storm water discharges in an urban area is investigated. The modeled domain stretches 116 km from the head of tide and includes hydrologic input from 33 streams and a number of municipal and industrial discharges. Bottom roughness was parameterized from sedimentological and geophysical surveys. Model validation to-date relies upon field observations and tidal harmonics for sea level and currents derived from the NOAA-NOS 1984–1985 circulation survey and a current survey conducted by the Philadelphia Water Department (PWD). Model representation of dye distribution compared favorably for observations of concentrations in the dye plume from 10 cross-sections spanning the extent of the plume over seven tidal cycles. The dye distribution was characterized by an initial period of high local storm water and stream inflows with low wind conditions, lasting for several tidal cycles, followed by a period of reduced fresh water input and increasing wind stress. The dye experiment provided a unique opportunity to observe the performance of the model through the transition between these two very different meteorological periods, and to explore the physical conditions driving the hydrodynamics through both observations and numerical experiments. The influences of local meteorological forcing and channel morphology on lateral mixing, dispersion and longitudinal dynamics are characterized.

In 2011, the City of Philadelphia, Pennsylvania; the Southeastern Pennsylvania Transportation Authority (SEPTA); and the Delaware Valley Regional Planning Commission (DVRPC) launched the Route 47 Service Enhancement Pilot Project. This project was conceived within the framework of the Transit First Committee. The pilot presented an opportunity to evaluate the effectiveness of low-cost operational initiatives that might have the ability to improve transit services in dense, urban environments. These strategies included bus stop consolidation, farside stop placement, and the switch from a time point–based scheduling system to a headway-based scheduling system. This joint initiative served as a test of the potential to build community support for a pilot, the impact of the interventions themselves, and the ability of the Transit First Committee to work together collaboratively. Although the pilot initiative did not deliver the time savings expected, the process provided important lessons for the city, SEPTA, and DVRPC that are applicable for other transit agencies operating in similar geographic, political, and economic environments. The results of the collaborative process necessary to get the pilot in motion helped to reconnect the city and SEPTA after years of distrust and discord. The initiatives piloted were scrutinized through data analysis, which provided not only an understanding of the impacts but also an awareness of operational performance issues. Ultimately, this extensive data analysis supported decision making, fostered agreement between stakeholders, and developed trust within the community.