Combined Sewer System

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1 Combined Sewer System Characterization Report Capital Region Water Harrisburg, PA February 2018 March 2017 Version 2.0

2 Table of Contents Section 1 Introduction Background Regulatory Context and Report Objective Combined Sewer System Overview Report Organization Section 2 Characterization of Precipitation Patterns Rain Gage & Gage Adjusted Radar Rainfall System Precipitation Statistics Rainfall Volume and Intensity Event Rank Storm Volumes Rainfall Event Frequency Precipitation Analysis Summary Section 3 Characterization of the Service Area, Collection, and Treatment System CRW Combined Sewer System Service Area Service Area Description Drainage Area Delineation CRW s Conveyance System Interceptor Sewers Pump Stations and Force Main Combined Sewer Regulators and Outfalls Collection System Trunk and Branch Sewers Inlets and Catch Basins Inspections and System Condition Advanced Wastewater Treatment Facility Wastewater and Solids Handling Processes AWTF Performance Improvements to AWTF Performance Section 4 Characterization of Receiving Water Conditions Regulatory Context Existing Characterization Identification of Waters Receiving CRW CSO Discharges Water Quality Standards Existing Water Quality Studies Pollutants of Concern Priority and Sensitive Areas References Section 5 Description of Data Collection and Monitoring Regulatory Context i

3 Table of Contents 5.2 Summary of Initial Flow Metering and Monitoring Program Plan Summary of Monitoring Status Precipitation Monitoring Suburban Community POC Monitoring Interceptor Monitoring Combined Trunk Sewer Monitoring at CSO Regulator Structures Separate Sanitary Catchment Monitoring CSO Outfall Boundary Condition Monitoring Section 6 Description of Hydrologic, Hydraulic, and Water Quality Modeling Regulatory Context Summary of CRW s Hydrologic & Hydraulic Model Model of CRW s Conveyance System Model of CRW Trunk Sewers Hydrologic Model Summary of Water Quality Modeling Plan Section 7 Characterization of System Response to Wet Weather Wet Weather Characterization of Existing CSOs Systemwide Performance Statistics Wet Weather Characterization of Existing Conditions by CSO Regulator ii

4 Table of Contents List of Figures Figure 1-1: Capital Region Water s (CRW s) Conveyance System Figure 2-1: Precipitation Monitoring Sites Figure 2-2: Spatial Distribution of the Rain Gauge Network and 1-km 2 Radar Grid Pixels Figure 2-3: Annual rainfall in Harrisburg, PA Figure 2-4: Median Monthly Precipitation Volumes in Harrisburg, PA Figure 2-5: Annual storm events in Harrisburg, PA Figure 2-6: Median Number of Monthly Events for Harrisburg, PA with +/- 1 Standard Deviation2-13 Figure 3-1: Location and Type of Sewershed/Catchment within CRW s Service Area Figure 3-2: CRW s Conveyance System Figure 3-3: Location of CRW CSOs Figure 3-4: Existing Structural Problems within the CRW collection System Figure 3-5: Process Flow Diagram for CRW AWTF Following Improvements Figure 4-1: Map of PADEP Fecal Coliform Sampling Locations Near Harrisburg Figure 5-1: Precipitation Monitoring Sites Figure 5-2: Suburban Community Point of Connection and Interceptor System Monitoring Sites Figure 5-3: Combined Trunk Sewer / CSO Regulator Flow Depth Monitoring Sites Figure 5-4: Separate Sanitary Catchment Area Monitoring Sites Figure 5-5: Paxton Creek and Susquehanna River CSO Outfall Boundary Condition Monitoring Figure 6-1: Interceptor and Major Trunk Sewer Model Figure 7-1: Peak Hydraulic Grade Line along the Front Street Interceptor during Typical Year Figure 7-2 Peak Hydraulic Grade Line along the Paxton Creek Interceptor during Typical Year Figure 7-3: Average Annual Regulator Overflow Frequency by Interceptor iii

5 Table of Contents List of Tables Table 2-1: Precipitation Monitoring Summary Table 2-2: Monthly and Annual Rainfall Volume for Harrisburg, PA Table 2-3: Median Monthly Precipitation Volumes (1) in Harrisburg, PA Table 2-4: Median Depths for the 20 Largest Storms of the Historic Dataset for Harrisburg, PA Table 2-5: Point Precipitation Intensity Estimates,* Harrisburg, PA, 1 Year Recurrence Interval Table 2-6: Monthly and Annual Rainfall Event Frequency for Harrisburg, PA Table 2-7: Median Monthly Precipitation Events in Harrisburg, PA with +/- 1 Standard Deviation Table 3-1. Catchment Area Types and Tributary Area Statistics Table 3-2: Key Characteristics of Interceptors in the CRW Conveyance System Table 3-3: Wet Well Parameters of Front Street and Spring Creek Pump Stations Table 3-4: Front Street Pump Station Wet Well Operating Levels Table 3-5: Spring Creek Wet Well Operating Levels Table 3-6: CSO Regulator Structures in the CRW System Table 3-7: CRW Rapid Assessment Inspection Summary Table 3-8: AWTF Basis of Design Wastewater Flows Table 4-1: Attainment Status of Waters Receiving CRW Combined Sewer System Discharges Table 4-2: Event Mean Concentrations (EMCs) of CSO Discharges to the Susquehanna River Table 4-3: PADEP Fecal Coliform Sampling Results for Locations Upstream of Harrisburg Table 4-4: PADEP Fecal Coliform Sampling Results for Locations Downstream of Harrisburg Table 4-5: PADEP Fecal Coliform Sampling Results for Locations in the Reach Near Harrisburg Table 4-6: PADEP Fecal Coliform Sampling Results Table 4-7: Event Mean Concentrations (EMCs) of CSO Discharges to Paxton Creek Table 4-8: Pollutants of Concern Discharging from CRW s Combined Sewer System Table 5-1: Status of Precipitation Data Collection Table 5-2: Status of Suburban Community POC Data Collection Table 5-3: Status of CRW Interceptor System Data Collection Table 5-4: Status of CRW CSO Regulator Structure Data Collection Table 5-5: Status of CRW Separate Sanitary Catchment Area Data Collection Table 6-1: Characteristics of CRW s Collection/Trunk Sewer Model Table 7-1: Systemwide Summary of Existing CSOs under Existing Conditions Table 7-2: Combined Sewer System Wet Weather Characterization of Current Conditions Table 7-3: Existing Combined Sewer System Wet Weather Characterization by CSO Regulator Appendices (Provided on CD) Appendix A Typical Year Rainfall Report Appendix B CSO Outfall Repair Early Action Project Schedule and Response to EPA Comments Appendix C Initial Flow Metering and Monitoring Program Plan (IFMMPP) and Addenda Appendix D Phase 2 Monitoring Program Appendix E CSO Activation Monitoring Pilot (CAMP) Study Evaluation Report Appendix F Sewer System Hydrologic and Hydraulic Model Report Appendix G Water Quality Modeling Plan iv

6 Section 1 Introduction 1.1 Background Capital Region Water (CRW), formerly known as The Harrisburg Authority, is a municipal authority organized under the Municipal Authorities Act, as amended, 53 Pa. Cons. Stat. Ann , that owns, operates, and maintains the wastewater and stormwater infrastructure within the City of Harrisburg, Pennsylvania, namely: A publicly owned treatment works ( POTW ) which includes a treatment plant known as the Capital Region Water Advanced Wastewater Treatment Facility ( AWTF ). A collection system ( Collection System ) that collects stormwater and wastewater from residential, commercial and industrial sources. Certain portions of the Collection System are served by combined sewers that receive wastewater and stormwater, and other portions are served by separate sanitary and storm sewer systems. A conveyance system ( Conveyance System ), including interceptors, pump stations, force mains, and CSO regulators, that conveys wastewater to the AWTF from CRW s collection system and from sewer systems owned, operated, and maintained by six suburban communities. CRW prepared and submitted to the Pennsylvania Department of Environmental Protection (PADEP) a Long Term Control Plan ( LTCP ) in January CRW s NPDES Permit requires implementation of the LTCP in order to achieve Commonwealth water quality standards in accordance with the schedule therein. EPA and PADEP have determined that CRW s LTCP, as presently drafted, is inadequate to comply with EPA s 1994 CSO Policy ( CSO Policy ), adopted by reference into Section 402(q) of the CWA, 33 U.S.C. 1342(q). As a result, CRW has entered into a partial Consent Decree (CD) with the United States and PADEP to, among other things, develop and submit a Combined Sewer System Characterization Report to support the revision of its LTCP. 1.2 Regulatory Context and Report Objective This deliverable is intended to satisfy Paragraph E(21) of CRW s partial Consent Decree (CD) with the United States and PADEP: 21. Existing System Characterization. By April 1, 2017, CRW shall submit an Existing System Characterization that includes all of the information required by CSO Policy Section II.C.1 to Plaintiffs for review and approval in accordance with the requirements of Section VI (Review and Approval of Deliverables). The Existing System Characterization shall include, but not be limited to, the following: a. CRW shall utilize the H&H Model updated, calibrated, and validated under Paragraph 15 to characterize the expected volume, frequency, and duration of CSO discharge events from 1-1

7 Section 1 Introduction each CSO during the Typical Year as identified in Paragraph 20, above, based on an interevent period of six (6) hours; b. CRW shall incorporate the results of its investigation of Priority Areas and Sensitive Areas, as required by Paragraph 19, above; c. CRW shall provide a characterization of current water quality in its Receiving Waters, based upon all available data, use of its Water Quality Model(s) in Receiving Waters in which the Demonstration Approach is being utilized, and its efforts to identify pollutants of concern as required by Paragraph 16, above. This report documents that CRW has developed a thorough understanding of its sewer system, the systems response to precipitation events of varying duration and intensity, the characteristics of the system overflows, and the water quality issues associated with its CSOs. The objective of the Combined Sewer System Characterization is to assist CRW develop appropriate measures to support the development of the long-term CSO control plan. 1.3 Combined Sewer System Overview The partial Consent Decree defines CRW s conveyance system as... the sewer conveyance system owned by CRW and formerly operated by the City, and currently owned and operated by CRW, including the conveyances which receive both wastewater and stormwater runoff from residential, commercial and industrial and combined sewage sources. The Conveyance System includes pump stations, interceptor sewers, force main, combined sewer outfalls and associated regulators. The conveyance system, shown in Figure 1-1, consists of the following components: The Asylum Interceptor conveys separate sanitary flow from the Borough of Penbrook, Lower Paxton Township, and Susquehanna Township to the Paxton Creek Relief Interceptor and the Paxton Creek Interceptor. The Spring Creek Interceptor conveys separate sanitary flow from the City of Harrisburg, the Borough of Paxtang, Lower Paxton Township, and Swatara Township to the Spring Creek Pump Station. The Front Street Interceptor extends along the northeast shore of the Susquehanna River, receives combined and separate sanitary flow from the City of Harrisburg and separate sanitary flow from Susquehanna Township, and conveys it to the Front Street Pump Station. The Paxton Creek Interceptor begins near Wildwood Lake, where it receives separate sanitary flow from Lower Paxton Township and Susquehanna Township; extends along the mainstem of Paxton Creek, where it receives combined and separate sanitary flow from the City of Harrisburg and separate sanitary flow from the Asylum Run / Paxton Creek Relief interceptors serving the Borough of Penbrook, Lower Paxton Township, and Susquehanna Township; and conveys these flows to the Front Street Pump Station. 1-2

8 Section 1 Introduction Figure 1-1: Capital Region Water s (CRW s) Conveyance System 1-3

9 Section 1 Introduction The Paxton Creek Relief Interceptor receives combined flow from the City of Harrisburg and conveys separate sanitary flow from the Asylum Interceptor to the Paxton Creek interceptor. The Hemlock Street Interceptor receives combined flow from the southern part of the City of Harrisburg and conveys it to the Spring Creek Pump Station. Two sewage pump stations convey flow from these interceptors to CRW s AWTF: The Front Street Pump Station receives flow from the Front Street and Paxton Creek interceptors The Spring Creek Pump Station conveys interceptor flow from the Hemlock Street and Spring Creek Interceptors. Both pump stations discharge into a common force main which conveys flow to the AWTF. 59 CSO regulator structures, located where the local combined sewer collection systems are connected to the interceptor sewers, control how much flow is directed to the AWTF, with the remainder discharged to the receiving water. 1.4 Report Organization Section 1 provides an introduction to the report contents, regulatory context, and combined sewer system overview. Section 2 provides a summary of the precipitation data, including volumes, intensities, frequencies, and distribution of precipitation events. Section 3 provides a summary of CRW s service area, its existing collection, conveyance, and treatment systems. Section 4 summarizes information and documentation related to characterizing current water quality conditions. Section 5 provides a summary of CRWs sewer system monitoring program including recent findings of monitoring data and analysis. Section 6 provides a summary of the hydrologic and hydraulic modeling program. Section 7 describes the wet weather response of the combined sewer system including volume, number, location, and frequency of combined sewer overflows. 1-4

10 Section 2 Characterization of Precipitation Patterns Capital Region Water (CRW) submitted a report on August 1, 2015 in conformance with the Partial Consent Decree describing a statistical evaluation of long-term local rainfall patterns and the identification of a representative or Typical Year for Combined Sewer Overflow (CSO) Long Term Control Plan (LTCP) development purposes. This section documents the methodology used for generating the representative precipitation year data for modeling existing baseline conditions and developing and evaluating wet weather control alternatives. The entire report is included as an appendix to this Combined Sewer System Characterization, Appendix A. 2.1 Rain Gage & Gage Adjusted Radar Rainfall System Two principal sources of long-term precipitation data were used to conduct the typical year analysis for the CRW service area. The gauge at the Capital City Airport, located directly west of downtown Harrisburg, PA, near the western shore of the Susquehanna River, starting from May 1, 1948 and extending through February 28, Data from 1948 through September 1991 were obtained from Gauge ID COOP , and data from was captured by Gauge ID FAA_ Hourly- KCXY. However, data records for years 1980 through 1987 and for years 1991 through 1996 are missing. There are 23 years of hourly precipitation data, collected from October 1, 1991 through December 31, 2013, available from the gauge at the Harrisburg International Airport, located southeast of downtown Harrisburg and approximately 6 miles from the Capital City Airport weather station. Data from this gauge record was used to fill some of the gaps in the precipitation record from the Capital City Airport gauge. There are six years of data overlap between the two gauges, spanning the period from 2007 through To support development of its LTCP, CRW installed a regional rainfall monitoring system throughout its service area in August 2014 that will be maintained indefinitely. The system consists of the two historic airport gages, rain gages at two CRW gaging stations originally installed in 2007, and six additional CRW gaging stations throughout CRW s service area. This system was established to define event-specific spatial variation in rainfall intensities and volumes for use in model calibration and, ultimately, model projections of historic CSO events. Figure 2-1 shows the rain gauge network locations in relation to Harrisburg and surrounding communities, while Table 2-1 summarizes the rain gauge network and the respective gauge period of record. 2-1

11 Section 2 Characterization of Precipitation Patterns Figure 2-1: Precipitation Monitoring Sites 2-2

12 Section 2 Characterization of Precipitation Patterns Table 2-1: Precipitation Monitoring Summary Gauge Name /Number Gauge Location Period of Record ID COOP Capital City Airport 5/1/ FAA_ Hourly-KCXY Capital City Airport /28/2013 Harrisburg International Airport Harrisburg International Airport 10/1/ /31/2016 RG1 Koons Park 9/3/ /31/2016 RG2 Market Street 8/1/ /31/2016 RG3 CRW AWTP 8/1/ /31/2016 RG4 Swatara 9/5/ /31/2016 RG5 United Water 9/12/ /31/2016 RG6 Lower Paxton 9/9/ /31/2016 RG7 East Pennsboro 9/6/ /31/2016 RG8 Steelton 9/5/ /31/2016 Rainfall data from these gages was used to develop gage-adjusted radar rainfall (GARR) information for storm events. Radar imagery was obtained from the Next-Generation Radar Doppler weather radar network operated by the National Weather Service, specifically the KCCX radar site located near State College, Pennsylvania, approximately 100 km from the City of Harrisburg. Level II data was obtained, which are the digital radial base data (reflectivity, mean radial velocity, and spectrum width) and dual polarization variables (differential reflectivity, correlation coefficient, and differential phase) output from the signal processor in the Radar Data Acquisition unit. These data are used to further determine spatially-distributed precipitation type, intensity, and volume information. Figure 2-2 shows the radar grid in relevance to the rain gauge network and municipal boundaries. Capital Region Water has contracted work to collect, analyze, and report high-resolution, spatially-distributed, gage-adjusted radar-rainfall data that will be used to further augment rain gauge data for assessing wet weather response of the combined sewer system. The rain gage precipitation data is compared to the next-generation radar data for each storm event to identify gages that appear to perform poorly or exhibit suspect behavior. Gages exhibiting synchronization issues, clogging, mechanical problems, or other suspicious behavior are identified and excluded from further analysis. Monthly representations of gage-adjusted radar rainfall have been developed since August 2014, and will continue to be generated monthly throughout the LTCP development process. The radar-estimated rainfall data is compared with gaged rainfall to identify and quantify any bias, defined as the varying differences between the average gage values and the average radar pixel estimates. The historic and monthly next-generation radar data is gage and bias adjusted. The resulting precipitation data is a combination of measured precipitation gage data and weather radar data accumulated to 5-minute intervals, geo-referenced, gage and bias corrected, and merged into a single and consistent dataset. The dataset provides an accurate estimate of the quantity, timing, and distribution of rainfall precipitation over the CRW service area. 2-3

13 Section 2 Characterization of Precipitation Patterns Figure 2-2: Spatial Distribution of the Rain Gauge Network and 1-km 2 Radar Grid Pixels The Typical Year Rainfall Report indicated that while event-specific spatial variation was anticipated, available regional long-term precipitation data and statistical evaluations (e.g., the National Oceanographic and Atmospheric Administration s (NOAA s) Atlas 14) do not show evidence of long-term spatial variation across the City of Harrisburg, nor are any topographic features present within Harrisburg that would produce a long-term spatial variation. The current data set is insufficient to demonstrate any long-term spatial variation in precipitation within Harrisburg. Therefore, it is reasonable to conclude that a uniform spatial distribution is appropriate for defining the typical year precipitation data set across the service area for development of the CSO LTCP. 2.2 Precipitation Statistics The Typical Year Rainfall Report included the analysis of the historical record gauge data from the Capital City Airport and the Harrisburg International Airport precipitation gauges, which are recorded in hourly increments. The analysis established specific criteria, such as precipitation volumes, the number and temporal distribution of storm events, and the peak intensity of events, to ensure that the results accurately reflected the long-term precipitation record. The report also included the analysis of more recent local gauge data recorded in 5 minute increments, provided at two CRW gauges with records extending from 2007 to 2013, to identify a contiguous 12 month period that reasonably correlates to the long-term record statistics. The additional resolution and refinement provided by the five minute rainfall data is required for the development of the LTCP 2-4

14 Section 2 Characterization of Precipitation Patterns for the greater Harrisburg area because many of the combined sewershed areas are relatively small, and hourly data would not accurately reflect their hydrologic and hydraulic (H&H) characteristics Rainfall Volume and Intensity The combined record from the two airport gauges provided a long-term historical record of 57 years. The average annual precipitation volume and the average annual number of storm events were determined, along with the associated standard deviations, for the extended precipitation record. Figure 2-3 shows the annual precipitation volume for each year in the long-term record from the combined gauge record. Also shown are the plus and minus one standard deviation values that depict the statistical 68 percent confidence intervals from the data set. The median annual rainfall for the 57 year record was inches, and the standard deviation was 8.08 inches. The 68% confidence interval extends from inches to inches. Table 2-2 provides the monthly and annual rainfall volumes from the long-term historical precipitation record for Harrisburg. The associated mean and median values, along with their standard deviations in inches and as a percent, are provided at the bottom of the table. Figure 2-3: Annual rainfall in Harrisburg, PA 2-5

15 Section 2 Characterization of Precipitation Patterns Table 2-2: Monthly and Annual Rainfall Volume for Harrisburg, PA Year Monthly Rainfall Volume (inches) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Total N/A 1982 N/A 1983 N/A 1984 N/A 1985 N/A 1986 N/A

16 Section 2 Characterization of Precipitation Patterns Table 2-2: Monthly and Annual Rainfall Volume for Harrisburg, PA Year Monthly Rainfall Volume (inches) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Total Mean Median St. Dev (inches) St. Dev (1) 50% 46% 41% 49% 58% 74% 52% 56% 82% 64% 46% 48% 20% St. Dev (2) 61% 50% 40% 51% 62% 83% 56% 63% 106% 75% 50% 49% 20% (1)Note: Standard deviation as a percent of the mean value (2)Note: Standard deviation as a percent of the median value 2-7

17 Section 2 Characterization of Precipitation Patterns Figure 2-4 shows the average monthly distribution of precipitation volumes based upon the long-term precipitation record. Also shown on the figure are the plus and minus one standard deviation values that depict the statistical 66 percent confidence intervals for the dataset. The analysis results show that precipitation volumes in the greater Harrisburg area are generally uniformly distributed throughout the year, from 2.40 inches in February to 3.56 inches in May. Seasonal variation is not significant. Table 2-3 provides the information in tabular form. The statistical results show that variability in monthly precipitation is significant, ranging from 40% in March to 106% in September. The inter-annual variability in annual precipitation is much less, at 20%. Figure 2-4: Median Monthly Precipitation Volumes in Harrisburg, PA Table 2-3: Median Monthly Precipitation Volumes (1) in Harrisburg, PA Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Median Standard. Deviation Standard. Deviation. as % (2) 61% 50% 40% 51% 62% 83% 56% 63% 106% 75% 50% 49% Median + 1 SD Median 1 SD (1)Note: All precipitation volumes are given in inches (2)Note: Standard deviation as a percent of the median value 2-8

18 Section 2 Characterization of Precipitation Patterns Event Rank Storm Volumes Analyses were conducted on the long-term precipitation record to develop event rank values of the annual median storm volumes. For each of the 57 years of the historical record, the largest storm volume was identified. The values were listed in order and the median value was identified, along with the associated standard deviation from that mean. The process was repeated for the second largest annual storms, the third largest storms, and so on. The resulting ranked list of the 20 largest annual storm volumes is provided in Table 2-4. Also included in the table are the standard deviations around each of the median depths, given in inches and as a percent. Table 2-4: Median Depths for the 20 Largest Storms of the Historic Dataset for Harrisburg, PA Event Rank Median Volume (inches) Standard Deviation (inches) Standard Deviation (percent) % % % % % % % % % % % % % % % % % % % % The National Oceanic and Atmospheric Administration (NOAA) has conducted statistical analyses for long-term record precipitation record gauges across the country, and distributes the results on their internet site as NOAA Atlas 14. NOAA Atlas 14, Volume 2, Version 3 provides precipitation intensity estimates for Harrisburg, based upon a partial duration frequency analysis of the long-term record. The analysis results for a one year recurrence interval are provided in Table 2-5. Also provided in the table are the upper and lower bounds of the 90% confidence interval. The probability that precipitation intensity estimates for a given duration and average recurrence interval will be greater than the upper bound, or less than the lower bound, is 5%. 2-9

19 Section 2 Characterization of Precipitation Patterns Table 2-5: Point Precipitation Intensity Estimates,* Harrisburg, PA, 1 Year Recurrence Interval Duration Precipitation for 1 Year Recurrence Interval Lower Bound 90% Confidence Interval Upper Bound 90% Confidence Interval 5-min min min min min *Note: all precipitation intensity estimates are given in inches Rainfall Event Frequency Figure 2-5 shows the annual total of significant precipitation events for each year in the longterm gauge record. The analysis indicated that the median number of significant precipitation events, events greater than 0.05 inches, over the long-term record was 86, and the standard deviation was 12.3 events. The 68% confidence interval extends from 73.7 events to 98.3 events. Table 2-6 provides the monthly and annual number of significant storms from the long-term historical precipitation record for Harrisburg. The associated mean and median values, along with their standard deviations as a number and as a percent, are provided at the bottom of the table. Figure 2-6 shows the average distribution of precipitation event frequency, based upon a minimum event volume of 0.05 inches and an inter-event period of 6 hours. Also shown on the figure are the plus and minus one standard deviation values. The figure shows that precipitation events in the greater Harrisburg area tend to be distributed evenly throughout the year, averaging from 6 to 9 events per month. The 66% confidence interval indicates an average variance range would extend from 4 to 12 events per month. Figure 2-5: Annual storm events in Harrisburg, PA 2-10

20 Section 2 Characterization of Precipitation Patterns Table 2-6: Monthly and Annual Rainfall Event Frequency for Harrisburg, PA Year Monthly Number of Significant (1) Storm Events Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Total N/A 1982 N/A 1983 N/A 1984 N/A 2-11

21 Section 2 Characterization of Precipitation Patterns Table 2-6: Monthly and Annual Rainfall Event Frequency for Harrisburg, PA Year Monthly Number of Significant (1) Storm Events Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Total 1985 N/A 1986 N/A Mean Median St. Dev (inches) St. Dev (2) 34% 37% 36% 32% 40% 40% 31% 36% 37% 41% 36% 44% 14% St. Dev (3) 36% 35% 33% 32% 40% 38% 34% 37% 42% 40% 34% 43% 14% (1)Note: A threshold value of 0.05 inches and an inter-event period of six hours were used to define significant precipitation events (2)Note: Standard deviation as a percent of the mean value (3)Note: Standard deviation as a percent of the median value 2-12

22 Section 2 Characterization of Precipitation Patterns Figure 2-6: Median Number of Monthly Events for Harrisburg, PA with +/- 1 Standard Deviation Table 2-7 provides the information in tabular form. The statistical results show that inter-annual variability in the monthly number of storms is significant, ranging from 32% in April to 43% in December. The inter-annual variability in annual precipitation is much less, at 14%. Table 2-7: Median Monthly Precipitation Events in Harrisburg, PA with +/- 1 Standard Deviation Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Median Stand. Deviation Stand. Dev. as %* 36% 35% 33% 32% 40% 38% 34% 37% 42% 40% 34% 43% Median + 1 SD Median 1 SD *Note: Standard deviation as a percent of the median value 2.3 Precipitation Analysis Summary The completed analyses of the long-term precipitation record for the Harrisburg area established the following specific statistical criteria for the typical year rainfall. The median annual rainfall is 39.8 inches, and the annual rainfall for the typical year should lie within the confidence range extending from 31.7 inches to 47.9 inches. The median annual precipitation event frequency is 86 storms, and the annual number of storms for the typical year should lie within the confidence range extending from 74 to 98 events. The statistical analysis results indicate the average peak intensity, for a range of durations, for storms with a one year recurrence interval. Depth, 2-13

23 Section 2 Characterization of Precipitation Patterns duration, frequency information from NOAA Atlas 14 for durations ranging from 5 minutes to 1 hour and recurrence intervals ranging from 1 year to 1,000 years are provided as a series of curves in Figure 2-7. Figure 2-7: Depth, Duration, Frequency curves based on NOAA Atlas 14 data for Harrisburg, PA The representative typical year precipitation record meets these criteria and accurately represents the long-term precipitation record for the CRW service area. When the typical year precipitation dataset is input into the existing condition H&H models, the simulated annual CSO statistics such as annual event frequency, volume and duration should closely match corresponding statistical averages of the long-term historical record, establish existing baseline conditions, and facilitate the development and evaluation of wet weather control alternatives. These statistics are discussed in Section 7 Characterization of System Response to Wet Weather. US-EPA guidance for the preparation of a LTCP clearly states that control alternatives are to be developed based upon the typical long-term rainfall record. CRW implemented written US-EPA guidance when developing and assessing alternatives, and utilized the typical year precipitation analysis approach. Sensitivity runs were subsequently conducted and considered to quantify performance under a range of precipitation conditions, including those imposed by climate change trends. The level of control provided by the CRW Program Plan is guided by the financial capability constraints of the service area rate payers. Therefore, the possible long-term effects of climate change will potentially impact the level of service provided by the Program Plan, but not impact the recommended control facilities. 2-14

24 Section 3 Characterization of the Service Area, Collection, and Treatment System 3.1 CRW Combined Sewer System Service Area Service Area Description The greater Harrisburg area is one of the 100 largest urban population centers in the United States, and the City of Harrisburg has a population of nearly 50,000 and a total land area of approximately 7 square miles. The City of Harrisburg is bounded by the Susquehanna River on the west and by suburban communities on the north, east and south. Capital Region Water operates the collection and conveyance systems within the City of Harrisburg. The collection system consists of inlets, laterals, branch sewers and trunk sewers, while the conveyance system consists of regulators, interceptors, pump stations, and force mains that convey combined wastewater to the Advanced Wastewater Treatment Facility (AWTF). CRW also provides conveyance and/or wastewater treatment to six suburban communities. Five of the suburban service communities (Lower Paxton Township, Swatara Township, Susquehanna Township, Paxtang Borough, and Penbrook Borough) are served by separate sanitary sewers that discharge into CRW s conveyance system, while Steelton Borough has a combined collection system and pumps its wastewater directly to CRW s AWTF via the Trewick Street Pump Station. Section includes a map showing the geographic limits of the suburban collection systems Drainage Area Delineation Figure 3-1 shows the City of Harrisburg and the areas served by its collection and conveyance systems. Sewershed drainage area delineation was refined using collection system data recently collected as part of CRW s GIS development program. Aerial photographs collected in 2013 were used to refine the impervious area properties of each sewershed and/or catchment areas. Table 3-1 indicates that approximately 2,387 acres (approximately 60 percent of contributing area) are served by CRW s combined sewer system (CSS), carrying a mix of domestic and industrial wastewaters which combine with stormwater during wet weather. Approximately 87 percent of the CSS (2,086 acres) is served by combined sewers that collects both stormwater and wastewater in a single sewer. The remainder of the CSS is served by a system of partially separated separate sanitary and storm systems, in which sanitary wastewater and/or stormwater discharge to combined sewers. The remaining 1,579 acres of the City s contributing area (approximately 40 percent) are served by CRW s separate sanitary sewer system. In this system, separate sanitary sewers discharge directly to CRW s conveyance system without passing through a CSO regulator (except SS-006, where a separate sanitary sewer is connected to the regulator at CSO-021). Regulator chamber CSO-021 receives flow from two drainage areas: a combined sewershed (S-021) and a separate sanitary catchment area (SS-006). CRW will investigate connecting SS-006 sanitary sewer directly to the Paxton Creek Interceptor under the CSO Long Term Control Plan. 3-1

25 Section 3 Characterization of the Service Area, Collection, and Treatment System Figure 3-1: Location and Type of Sewershed/Catchment within CRW s Service Area 3-2

26 Section 3 Characterization of the Service Area, Collection, and Treatment System Stormwater is either collected by a CRW separate storm sewer and conveyed to Paxton Creek or the Susquehanna River (except SS-013, where CRW s separate storm sewer discharges to CSO- 048), or via storm sewers and/or surface drainage owned by other entities (e.g., the Commonwealth of Pennsylvania, Harrisburg Area Community College, or individual property owners). Table 3-1. Catchment Area Types and Tributary Area Statistics Interceptor Sewershed Combined Sewer System [1] Combined Sewer Catchments (ac) [2] Sanitary / Storm to Combined (ac) [3] Sanitary to Combined; Storm to River CRW MS4 (ac) Separate Sewer System Sanitary to Interceptor [4] Storm to Combined (ac) [5] Storm to River Non- Contributing Area (ac) Front Street Other MS4 (ac) CRW MS4 (ac) Other MS4 (ac) Separate Sanitary Outside City* (ac) Paxton Creek 1, Hemlock Street Paxton Creek Relief Asylum Run Spring Creek Total 2, Percent of City 46% 7% 4% 1% 4% 19% 7% 12% - Percent of Contributing Area 53% 8% 5% 1% 4% 22% 7% CRW s Conveyance System Interceptor Sewers CRW s conveyance system, depicted in Figure 3-2, consists of approximately 14 miles of interceptor sewer, ranging in size from 24-inch circular to 60-inch by 72-inch arch or rectangular pipe, as summarized in Table 3-2. Interceptor cross-sectional sizes/shapes and invert elevations were confirmed during an interior inspection and recorded in CRW s GIS. The conveyance system consists of the following components: Separate Sanitary Sewer Conveyance System The Asylum Interceptor conveys separate sanitary flow from the Borough of Penbrook, Lower Paxton Township, and Susquehanna Township to the Paxton Creek Relief Interceptor and the Paxton Creek Interceptor. The Spring Creek Interceptor conveys separate sanitary flow from the City of Harrisburg, the Borough of Penbrook, Borough of Paxtang, Lower Paxton Township, and Swatara Township to the Spring Creek Pump Station. 3-3

27 Section 3 Characterization of the Service Area, Collection, and Treatment System Figure 3-2: CRW s Conveyance System 3-4

28 Section 3 Characterization of the Service Area, Collection, and Treatment System Combined Sewer System Conveyance System The Front Street Interceptor extends along the northeast shore of the Susquehanna River, receives combined and separate sanitary flow from the City of Harrisburg and separate sanitary flow from Susquehanna Township, and conveys it to the Front Street Pump Station. The Paxton Creek Interceptor begins near Wildwood Lake, where it receives separate sanitary flow from Lower Paxton Township and Susquehanna Township; extends along the mainstem of Paxton Creek, where it receives combined and separate sanitary flow from the City of Harrisburg and separate sanitary flow from the Asylum Run / Paxton Creek Relief interceptors serving the Borough of Penbrook, Lower Paxton Township, and Susquehanna Township; and conveys these flows to the Front Street Pump Station. The Paxton Creek Relief Interceptor receives combined flow from the City of Harrisburg and conveys separate sanitary flow from the Asylum Interceptor to the Paxton Creek interceptor. The Hemlock Street Interceptor receives combined flow from the southern part of the City of Harrisburg and conveys it to the Spring Creek Pump Station. All CRW interceptor sewers were recently cleaned and inspected according to CRW s nine minimum control plan, with interceptors in poor structural conditions scheduled for early action rehabilitation under the Partial Consent Decree. Table 3-2: Key Characteristics of Interceptors in the CRW Conveyance System Interceptor Type Size (inches) Length (miles) Material Number Of CSO Outfalls CSO Discharge Receiving Water Front Street (FSI) Combined 39 x 36; 40; Concrete, VCP 27 Susquehanna River Paxton Creek (PCI) Combined 59 x 48; 60 x Concrete 25 Paxton Creek Hemlock Street (HSI) Combined Concrete, VCP 5 Paxton Creek Spring Creek (SCI) Sanitary Concrete, CMP, DIP 0 N/A Paxton Creek Relief (PCRI) Combined Concrete 1 Paxton Creek Asylum Run (ARI) Sanitary Concrete, VCP 0 N/A Pump Stations and Force Main Two sewage pump stations convey flow from these interceptors to CRW s AWTF. The Front Street Pump Station receives flow from the Front Street and Paxton Creek interceptors, while the Spring Street Pump Station conveys interceptor flow from the Hemlock Street and Spring Creek Interceptors. The Front Street Pump Station discharges to a 48-inch force main; the Spring Creek discharges to a 24-inch force main, which then discharges to the Front Street Pump Station force main. Immediately before reaching the AWTF, the force main expands to a 54-inch diameter. 3-5

29 Section 3 Characterization of the Service Area, Collection, and Treatment System Table 3-3 summarizes the dimensions of the wet wells receiving wastewater from CRW s interceptors. The Front Street Pump Station has 4 pumps, each pump has a nominal capacity of 10,000 GPM - two of them are variable speed, and the other two are constant speed. Table 3-4 presents the operating level of each of these pumps. The Spring Creek pump station has 3 pumps, each pump has a nominal capacity of 8,350 GPM and all are variable speed. Table 3-5 presents the operating level of each of these pumps. Table 3-3: Wet Well Parameters of Front Street and Spring Creek Pump Stations Wet Well Parameters Front Street Wet Well Spring Creek Wet Well Wet Well Size 47 ft x 20 ft 25 ft x 20 ft Bottom Elevation 286 ft 282 ft High Water Alarm 296 ft ft Overtopping 310 ft 312 ft Table 3-4: Front Street Pump Station Wet Well Operating Levels Operating Condition Rising Wet Well Levels (feet) Dropping Wet Well Levels (feet) Lead Variable Speed Pump st Lag Variable Speed Pump nd Lag Variable Speed Pump rd Lag Variable Speed Pump Note: High Water Alarm = Low Water Alarm = Bottom of Wet Well = Table 3-5: Spring Creek Wet Well Operating Levels Operating Condition Rising Wet Well Levels (feet) Dropping Wet Well Levels (feet) Lead Pump st Lag Pump High Water 5.5 Low Water 1.0 Notes: 1. Levels referenced to bottom of wet well 2. The third pump must be placed into service manually. Both the Front Street and Spring Creek Pump Stations have emergency overflows that are permitted CSO outfalls. CSO-002 is located at the Front Street Pump Station and CSO-003 is located at the Spring Creek Pump Station, and both structures have simple weir controls. Hydrologic and hydraulic modeling indicates that neither CSO structure discharges during typical year rainfall simulations. According to CRW s Nine Minimum Control Plan, both pump stations are over 50-years old and in need of significant remedial maintenance, while a recent inspection of CRW s force main did not identify any leaks, stable gas pockets, or priority anomalies. CRW proceeded with the design for upgrades to the Front Street Pump Station in 2016, and construction will be scheduled during the development of the CSO Long-Term Control Plan (LTCP), due April 1, CRW is currently 3-6

30 Section 3 Characterization of the Service Area, Collection, and Treatment System evaluating options for the upgrade or replacement/relocation of the Spring Creek Pump Station in association with the development of the LTCP Combined Sewer Regulators and Outfalls Fifty-nine CSO regulator structures, located where the combined sewer collection systems are connected to the interceptor sewers, control how much flow is directed to the AWTF, with the remainder discharged to the receiving water. Figure 3-3 indicates the configuration of the 59 CSO regulators within CRW s conveyance system, each discharging to a CSO outfall pipe. Table 3-6 describes each regulator within CRW s system, indicating there are three major types of regulators serving CRW s system: Mechanical Brown and Brown (B&B) equipment coupled with a low-head weirs control CSOs at 46 regulator structures. These B&B regulators, some operated with chains and some with rods, are currently set to completely close and prevent wet weather flow from entering the interceptor when flow depths exceed the weir height. Fixed orifices, accompanied by low-head weirs or high pipes, control CSOs at 13 regulator structures. Emergency overflow structures serve the Front Street and Spring Creek pump stations, allowing CSOs when interceptor flow capacity exceeds the hydraulic capacity of the pump station. Typically, Nine Minimum Control evaluations would include assessing the possibility of increasing the orifice openings of the B&B regulators during wet weather conditions to increase CSO capture. However, hydrologic and hydraulic model simulations indicate that adjusting the B&B regulators would surcharge the interceptor. The resulting increase in hydraulic pressure would create potential adverse conditions along interceptor reaches, specifically where CCTV inspections indicated reaches of damaged pipe in need of rehabilitation. A system of flap gates and/or flood gates are provided at most regulators to control river intrusion during flood conditions along the Susquehanna River and Paxton Creek. The condition of these regulator structures, outfall pipes, and river intrusion control systems are being evaluated under CRW s Nine Minimum Control Plan. 3-7

31 Section 3 Characterization of the Service Area, Collection, and Treatment System Figure 3-3: Location of CRW CSOs 3-8

32 Section 3 Characterization of the Service Area, Collection, and Treatment System Table 3-6: CSO Regulator Structures in the CRW System CSO ID Location Regulator Category Regulator Type (1) Interceptor Receiving Water CSO-002 Front St. Pump Station Emergency Overflow Not Applicable Front Street Susquehanna River CSO-003 Spring Creek Pump Station Emergency Overflow Not Applicable Paxton Creek Paxton Creek CSO-004 Front & Vaughn Brown and Brown B Front Street Susquehanna River CSO-005 Front & Lewis Brown and Brown A Front Street Susquehanna River CSO-006 Front & Geiger Brown and Brown A Front Street Susquehanna River CSO-007 Front & Peffer Brown and Brown A Front Street Susquehanna River CSO-008 Front & Muench Brown and Brown A Front Street Susquehanna River CSO-009 Front & Hamilton Brown and Brown A Front Street Susquehanna River CSO-010 Front & Reilly Brown and Brown A Front Street Susquehanna River CSO-011 Front & Calder Brown and Brown A Front Street Susquehanna River CSO-012 Front & Verbeke Brown and Brown A Front Street Susquehanna River CSO-013 Front & Cumberland Brown and Brown A Front Street Susquehanna River CSO-014 Front & Boas Fixed Orifice C Front Street Susquehanna River CSO-015 Front & Forster Brown and Brown A Front Street Susquehanna River CSO-016 Front & Liberty Brown and Brown A Front Street Susquehanna River CSO-017 Front & Market Brown and Brown A Front Street Susquehanna River CSO-018 Front & Mulberry Brown and Brown A Front Street Susquehanna River CSO-019 Front & Paxton Brown and Brown B Front Street Susquehanna River CSO-020 Front & Hanna Brown and Brown B Front Street Susquehanna River CSO-021 Cameron & Schuylkill Brown and Brown A Paxton Creek Paxton Creek CSO-022 Cameron & Forrest Brown and Brown B Paxton Creek Paxton Creek CSO-023 Cameron & Calder Fixed Orifice C Paxton Creek Paxton Creek CSO-024 Hill Chamber (T.R.W.) Fixed Orifice C Paxton Creek Paxton Creek CSO-025 N. Cameron & Cumberland Brown and Brown A Paxton Creek Paxton Creek CSO-026 S. Cameron & Cumberland Brown and Brown B Paxton Creek Paxton Creek CSO-027 Ninth & Cumberland Brown and Brown B Paxton Creek Paxton Creek CSO-028 Ninth & Herr Brown and Brown A Paxton Creek Paxton Creek CSO-029 E. Cameron & North Brown and Brown A Paxton Creek Paxton Creek CSO-030 W. Cameron & North Brown and Brown A Paxton Creek Paxton Creek CSO-031 Cameron & State Brown and Brown A Paxton Creek Paxton Creek CSO-032 W. Cameron & Walnut Brown and Brown B Paxton Creek Paxton Creek CSO-033 E. Cameron & Walnut Brown and Brown B Paxton Creek Paxton Creek CSO-034 S. Market & Cameron Brown and Brown A Paxton Creek Paxton Creek 3-9

33 Section 3 Characterization of the Service Area, Collection, and Treatment System Table 3-6: CSO Regulator Structures in the CRW System CSO ID Location Regulator Category Regulator Type (1) Interceptor Receiving Water CSO-037 Tenth & Market Brown and Brown A Paxton Creek Paxton Creek CSO-038 Tenth & Chestnut Brown and Brown A Paxton Creek Paxton Creek CSO-039 S. Mulberry & Cameron Brown and Brown A Paxton Creek Paxton Creek CSO-040 N. Mulberry & Cameron Brown and Brown B Paxton Creek Paxton Creek CSO-041 W. Mulberry & Cameron Brown and Brown B Paxton Creek Paxton Creek CSO-042 S. Kittatinny & Cameron Brown and Brown A Paxton Creek Paxton Creek CSO-043 N. Kittatinny & Cameron Brown and Brown A Paxton Creek Paxton Creek CSO-044 Cameron & Berryhill Fixed Orifice D Paxton Creek Paxton Creek CSO-045 Paxton Street (South) Fixed Orifice D Paxton Creek Paxton Creek CSO-046 Paxton Street (North) Fixed Orifice D Paxton Creek Paxton Creek CSO-048 Tenth & Shannon Brown and Brown A Paxton Creek Paxton Creek CSO-049 Front & Schuylkill Brown and Brown A Front Street Susquehanna River CSO-050 Seneca & Susquehanna Brown and Brown A Front Street Susquehanna River CSO Woodbine & Green Brown and Brown A Front Street Susquehanna River CSO-051 Woodbine & Front Fixed Orifice C Front Street Susquehanna River CSO-052 Front & State Brown and Brown A Front Street Susquehanna River CSO-053 Front & South Brown and Brown A Front Street Susquehanna River CSO-054 Front & Pine Brown and Brown A Front Street Susquehanna River CSO-055 Front & Locust Brown and Brown A Front Street Susquehanna River CSO-056 Front & Walnut Brown and Brown A Front Street Susquehanna River CSO-057 Cherry & Mulberry Brown and Brown A Front Street Susquehanna River CSO-058 Front & Tuscarora Brown and Brown B Front Street Susquehanna River CSO-059 Kittatinny & Crescent Fixed Orifice C Paxton Creek Paxton Creek CSO-060 Salmon Street Fixed Orifice C Hemlock Street Paxton Creek CSO-061 Tenth & Sycamore Fixed Orifice C Hemlock Street Paxton Creek CSO-062 Shanois Street Fixed Orifice C Hemlock Street Paxton Creek CSO-063 Cameron & Hanover Fixed Orifice C Hemlock Street Paxton Creek CSO-064 Cameron & Magnolia Fixed Orifice C Hemlock Street Paxton Creek Note: Type A: variable control orifices with chain drives Type B: variable control orifices with rod drives Type C: fixed control orifices with diversion weirs Type D: fixed control orifices with elevated outfall pipes 3-10

34 Section 3 Characterization of the Service Area, Collection, and Treatment System 3.3 Collection System The partial Consent Decree defines CRW s collection system as... the municipal wastewater collection and transmission system formerly owned and operated by the City, and currently owned and operated by CRW, including sewers, manholes, and other associated appurtenances designed to collect and convey municipal sewage and wastewaters (domestic, commercial, and industrial) to the Conveyance System. CRW s combined sewer collection system consists of approximately 60 percent of the total collection system, consisting of combined and separate sanitary sewers that lie upstream of a CSO regulator structure Trunk and Branch Sewers CRW has divided its collection system into trunk sewers and branch sewers based upon criteria provided in the partial CD and to focus LTCP development on its most important elements: Branch sewers within the combined sewer system collect combined wastewater from individual properties, inlets/catch basins within the public ROW, and other small-diameter sewers, and discharge to the trunk sewers. Trunk sewers within the combined sewer system collect combined wastewater and stormwater from branch sewers, and discharge to the CSO regulator structures. These trunk sewers are represented in CRW s hydraulic model of its combined sewer system, required under the Partial Consent Decree to represent 15 to 20 percent of the pipes within CRW s collection system meeting the following criteria: Combined sewers 42 or greater. Separate sanitary sewers 18 or greater that drain into the combined sewer system, and Additional sewers necessary to represent the downstream portion of the collection system discharging to each CSO regulator, including major flow split manholes within the collection system. In order to properly characterize its collection system, CRW recently completed a rapid assessment using a pole camera to inspect each collection system manhole and its connecting pipe segments. CRW utilized this rapid assessment data to update its GIS mapping of the collection system to confirm and enhance pipe sizes/materials, system connectivity, and catchment boundaries. It also revealed numerous, previously unknown flow-splitting manholes within the collection system that can divert flows between catchments and affect a CSO regulator capture efficiency. The locations of these flow-splitting manholes are shown on Figure 3-1. The flow splitting manholes with significant tributary catchment areas were incorporated into the H&H model, and their hydraulic operation will be optimized as part of the LTCP Inlets and Catch Basins CRW s combined collection system also includes approximately 4,300 inlets and catch basins. According to its Nine Minimum Control Plan, CRW is performing remedial inspection, cleaning and repair of approximately 50 to 75 percent of all inlets and catch basins that are partially to completely blocked with debris and often require structural repair once cleaned. However, hydrologic and hydraulic model simulations of clean inlet conditions did not reveal substantial 3-11

35 Section 3 Characterization of the Service Area, Collection, and Treatment System increases in flow. Continuing flow monitoring activities along the interceptor system should be able to detect and quantify how interceptor flow changes over time as more inlets are cleaned Inspections and System Condition In the initial stages of characterizing the CRW sewer system, CRW needed to quickly update its original GIS mapping of the configuration of the combined and separate sewer collection systems within the service area. It would not be possible to meet the Partial Consent Decree schedule and milestone deadlines by televising the entire system. Therefore, CRW elected to implement a Rapid Assessment Inspection Program, conducted via a pole camera inspection of every known manhole and connecting pipe within the collection system. The information gathered through the Rapid Assessment Inspection Program was successfully used to delineate the combined sewershed and separate sewer catchment areas within the CRW collection system. A map of the CRW collection system and the sewershed/catchment areas was provided in Figure 3-1. Rapid Assessment Inspections: CRW retained a contractor to perform the collection system Rapid Assessment Inspection Program in 2015 and The inspection observations were divided between operations and maintenance (O&M) findings and structural findings. O&M findings consist of defects related to the operation of the sewer system. Defects such as root intrusions and debris and grease deposits are examples of O&M defects. Structural defects pertain to any issue that may jeopardize the structural integrity of the pipe or manhole. Cracks, fractures, holes, exposed rebar, and missing bricks are examples of structural defects. Table 3-7 provides a summary of the miles of pipe and the number of manholes and outfalls that were inspected. The inspection observations were divided between operations and maintenance (O&M) findings and structural findings. Table 3-7: CRW Rapid Assessment Inspection Summary Combined/Separate Sewer System Miles of Pipe Number of Manholes/Outfalls Inspection Period Collection System Trunk Sewers Collection System Branch Sewers 92 2, Separate Storm Sewers Total 139 3,102 - The zoom camera inspections allowed for a rapid assessment of the condition of the pipes within CRW s collection system. Since inspections were conducted from the manhole access points only, each pipe has an upstream and downstream video that was captured. By analyzing both the upstream and downstream videos, a general condition assessment was performed for the viewable portion of each pipe, and preliminary rehabilitation recommendations were made. If nothing is preventing visibility within the pipe, fifty feet or more of the pipe length is viewable from videos taken at both the upstream and downstream manholes, which is generally sufficient for providing a preliminary characterization of the pipe. However, for pipes with bends, partial obstructions, or long distances between manholes, the assessment was more limited. 3-12

36 Section 3 Characterization of the Service Area, Collection, and Treatment System CRW analyzed the rapid assessment data, and assigned each manhole a priority level, which reflects the number and severity of defects that were identified. Scores were given on a scale of one through five, with one being the lowest priority level and five being the highest. CRW also analyzed pipe assessments of the zoom camera inspection findings applying a modified NASSCO PACP 1 protocol. The results indicated that 17% of the pipes that were inspected were in excellent condition, 19% in good condition, 25% in fair condition, 21% in poor condition, and 17% in very poor condition. A map showing the locations of known significant sewer pipe defects that require rehabilitation is provided in Figure 3-4 (low/medium severity defects are not shown). Ongoing CCTV Inspections and Assessments: While the collected Rapid Assessment Inspection data were essential in meeting the PCD schedule, there were understood limitations to the information provided because conditions within the pipe segments beyond the manhole inspection limits could not be observed. Subsequently, CRW developed and is implementing a prioritized CCTV inspection program to fill in the information gaps at a pace within their capabilities. CRW is in the process of conducting a prioritized remedial CCTV inspection of the entire collection system to eliminate risk associated with unknown defects, especially for critical sewers which have a high consequence of failure. To expedite the process, CRW has committed to purchasing a second CCTV truck and hiring additional staff to operate it. Outside contractors may also be used, as necessary, to supplement in-house CCTV capabilities. It is important to note that the CCTV inspection program is likely to identify additional defects not seen by the rapid assessment inspections which will elevate the condition score, and thus the recommendation priority, of many pipes. CRW is utilizing its Cityworks Asset Management System to document completed CCTV inspections, prioritize future CCTV inspections, and manage the pace at which inspections are conducted. Once the remedial CCTV inspections are completed on a system-wide basis, CRW will be able to transform its CCTV inspections from a remedial program to a preventative O&M program. 1 National Association of Sewer Service Companies, Pipeline Assessment and Certification Program 3-13

37 Section 3 Characterization of the Service Area, Collection, and Treatment System Figure 3-4: Existing Structural Problems within the CRW Collection System. 3-14

38 Section 3 Characterization of the Service Area, Collection, and Treatment System 3.4 Advanced Wastewater Treatment Facility The Advanced Wastewater Treatment Facility (AWTF) receives the wastewater flows from Front Street Pump Station and the Spring Creek Pump Station in a common force main, while flows from the Borough of Steelton are pumped directly to the AWTF. The 5-year average annual wastewater flow at the AWTF during 2013 to 2017 was 21.4 million gallons per day (MGD). This flow is attributed to residential, non-residential, commercial, industrial and governmental users. The permitted design hydraulic capacity of the AWTF is 45 MGD. Flows from the Front Street and Spring Creek Pump Stations combine and enters the facility via a 48-inch diameter force main. Flows from the Steelton Pump Station enter the plant via a 30-inch diameter force main. Wastewater flows are screened at the pump stations by mechanically-cleaned bar screens. The two force mains combine into a 54-inch diameter influent pipe at the AWTF Wastewater and Solids Handling Processes The wastewater and solids handling processes for the current AWTF and for the AWTF following completion of the improvements are illustrated on Figures and in Section 3 of the Operations and Maintenance Manual. A flow diagram of current AWTF, with the completion of recent improvements, is provided in Figure 3-5. Headworks Facilities Wastewater flow passes through Chamber A, then to the influent channel for the four vortex grit removal units. Effluent from the grit removal units flows through Chamber B followed by a venturi flow meter located in the 54-inch pipe in the Control Building which is used to measure total plant flow. Improvements to the headworks facility, which will increase the wet weather treatment capacity, have been designed and construction will continue through Primary Treatment Facilities After the flow meter, wastewater is conveyed to the primary influent channel that distributes flow between the four primary clarifiers. Primary sludge is combined with waste activated sludge, and conveyed to the gravity thickeners. The AWTF now has the capability for Chemically Enhanced Primary Treatment (CEPT). Ferric chloride (coagulant) can be added to the 48-inch diameter force main upstream of the vortex grit removal tanks and polymer (flocculant) can be added at the outlet to the vortex grit removal tanks. CEPT can be used to improve TSS and BOD removal during peak loading periods. Secondary and Tertiary Treatment Facilities Settled wastewater overflows the clarifiers weirs to an effluent channel leading to Chamber C and the Settled Wastewater Pump Station. All settled wastewater flow, up to 45 mgd, is pumped to the secondary process. Peak flows above 45 mgd are bypassed around the secondary process at Chamber C and directed to the chlorine contact tank for disinfection. Settled wastewater flows to the secondary process through a distribution box where flow is split between the three Oxygenation Tanks. The secondary treatment process is based on High Purity Oxygen Activated Sludge (HPOAS) technology wherein the Oxygenation Tanks are covered and aeration is achieved by high purity oxygen produced by the on-site cryogenic facility. 3-15

39 Section 3 Characterization of the Service Area, Collection, and Treatment System Figure 3-5: Process Flow Diagram for CRW AWTF Following Improvements Source: Harrisburg Advanced Wastewater Treatment Facility Improvements Project. Basis of Design Report. Prepared by AECOM, February

40 Section 3 Characterization of the Service Area, Collection, and Treatment System Each Oxygenation Tank consists of four cells, currently operated as a four stage carbonaceous reactor. Following completion of the improvements project, the first cell of each tank will be a pre-anoxic zone to remove a portion of the nitrate from the wastewater. The following three cells are aerobic zones for carbonaceous BOD removal. Mixed liquor from the Oxygenation Tanks will be conveyed to a new Bioreactor comprised of three main zones; aerobic, swing and anoxic zones. The swing zone may be operated as an aerobic or anoxic zone to optimize treatment process performance. A supplemental carbon source (i.e., methanol) can be added to the swing and anoxic zone to complete the nitrogen removal treatment process (denitrification). Mixed liquor overflows from the last pass of the Bioreactor anoxic zone into the post-aeration channel which is aerated to re-oxygenate and strip dissolved nitrogen gas in the mixed liquor. From the post-aeration channel, mixed liquor flows to the former alum tank and is distributed among the six final settling tanks via weir gates. Manually operated weir gates are used to control flow to each tank. Effluent from the final clarifiers is conveyed to the chlorine contact tanks where it is disinfected using chlorine gas and chlorinators prior to discharge to the Susquehanna River. Sludge and Solids Handling Facilities Return Activated Sludge (RAS) collected in the final settling tanks flows to the RAS pump station wet well where it is pumped to the RAS regeneration tank. This new side stream treatment process combines the filtrate from the sludge dewatering belt filter presses with RAS for nitrification treatment in the covered RAS regeneration tank using high pure oxygen. The overflow from the RAS regeneration tank is then distributed between the Oxygenation Tanks AWTF Performance A hydraulic capacity evaluation indicated that the peak hydraulic capacity of the AWTF through primary treatment is 80 MGD up to the 25-year recurrence interval river stage. The anticipated future peak hydraulic and treatment capacities for primary treatment are 80 MGD. Wastewater flows up to 45 MGD receive full treatment. Peak wet weather flows above 45 MGD bypass secondary treatment and are diverted to the chlorine contact tanks for disinfection following primary treatment. For example, the AWTF experienced 19 wet weather events in 2016 that exceeded the hydraulic capacity of the secondary treatment system, triggering a bypass. Further details about AWTF performance during wet weather events is contained in CRW s semi-annual reports required under the partial Consent Decree. The solids handling processes (gravity thickener/fermenters, anaerobic digesters, BFPs) are not considered critical facilities during wet weather, since their operation is not essential during a typical wet weather event with a duration of several hours up to a couple of days. Beyond a couple of days, the absence of solids handling facilities would have an impact on the performance of the AWTF as the accumulation of solids in the liquid process train would deteriorate effluent quality. Table 3-8 indicates the peak flow that critical facilities can hydraulically pass with the largest unit out of service without damaging the equipment. Most of the facilities that do not have multiple units can be taken out of service using bypass provisions; however, this may adversely impact the overall performance of the AWTF. The Operators make every effort to keep all critical 3-17

41 Section 3 Characterization of the Service Area, Collection, and Treatment System facilities in service during wet weather in order to maintain treatment performance requirements. Critical facilities should only be taken out of service for maintenance purposes. A short-term peak flow capacity of the AWTF has not been firmly established because the hydraulic capacity of the plant is affected by the river stage. It has been estimated that maximum plant flow capacity is between MGD, but that short term peak flows of up to 78 MGD may be possible through the plant with a secondary bypass of flows above 45 MGD 2. Table 3-8: AWTF Basis of Design Wastewater Flows 3 Design Flow Parameter Flow, MGD Annual Average Daily Maximum 30-Day Average Maximum 7-Day Average Maximum Daily Average Improvements to AWTF Performance Construction of the AWTF Nutrient Removal Upgrade project commenced in March 2014 and was completed in The project included approximately 4.5 million gallons of new biological reactor tankage and numerous associated appurtenances to upgrade treatment capabilities for nitrogen removal. During the first half of 2017 the following key tasks were accomplished at the AWTF: Design completion and bidding for the new headworks facility. Completion of 30% design for the primary digester improvements. Start of design for the primary settling tank modifications. The following are anticipated projects at the AWTF for the second half of 2017: Commence construction of a new headworks screening facility at the AWTF. Complete design for the Primary Digester Nos. 1 & 2. Continue design of improvements to the Primary Settling Tanks. 2 Draft Report Act 537 Plan Update Revision/Long-Term Control Plan prepared by Brinjac Engineering and Malcom Pirnie, August Data from Harrisburg Advanced Wastewater Treatment Facility, Improvements Project, Basis of Design Report prepared by AECOM, February

42 Section 4 Characterization of Receiving Water Conditions 4.1 Regulatory Context Capital Region Water (CRW) has previously developed documentation of water quality studies and priority pollutants of concern in response to a partial Consent Decree (CD) with the United States and PADEP. This section summarizes content that was previously developed to satisfy Paragraph E(21) of CRW s partial Consent Decree (CD) with the United States and PADEP: 21. Existing System Characterization. By April 1, 2017, CRW shall submit an Existing System Characterization that includes all of the information required by CSO Policy Section II.C.1 to Plaintiffs for review and approval in accordance with the requirements of Section VI (Review and Approval of Deliverables). The Existing System Characterization shall include, but not be limited to, the following: a. CRW shall utilize the H&H Model updated, calibrated, and validated under Paragraph 15 to characterize the expected volume, frequency, and duration of CSO discharge events from each CSO during the Typical Year as identified in Paragraph 20, above, based on an inter-event period of six (6) hours; b. CRW shall incorporate the results of its investigation of Priority Areas and Sensitive Areas, as required by Paragraph 19, above; c. CRW shall provide a characterization of current water quality in its Receiving Waters, based upon all available data, use of its Water Quality Model(s) in Receiving Waters in which the Demonstration Approach is being utilized, and its efforts to identify pollutants of concern by Paragraph 16, above. Section II.C.1 of the CSO Policy states: b. Combined Sewer System Characterization The permittee should evaluate the nature and extent of its sewer system through evaluation of available sewer system records, field inspections and other activities necessary to understand the number, location and frequency of overflows and their location relative to sensitive areas and to pollution sources in the collection system, such as indirect significant industrial areas. 4.2 Existing Characterization Identification of Waters Receiving CRW CSO Discharges CRW s combined sewer system drains stormwater and wastewater from approximately 2,387 acres within the City of Harrisburg, or approximately 60 percent of the City s contributing area. The following Waters of the Commonwealth directly receive discharges from CRW s combined sewer system: The east shore of the Susquehanna River within the City of Harrisburg 4-1

43 Section 4 Characterization of Receiving Water Conditions The main stem of Paxton Creek from its confluence with the Susquehanna River upstream to approximately the southern border of Harrisburg Area Community College, and excluding the portions of Asylum Run within the City. CRWs combined sewer system also lies within the Chesapeake Bay watershed, and is subject to the objectives of the Pennsylvania Chesapeake Watershed Implementation Plan. Existing Regulated Industrial Users In accordance with EPA s CSO guidance, a preliminary assessment was performed as part of the development of CRW s Nine Minimum Control Plan to ascertain whether industrial discharges are concentrated in certain areas, thereby having the potential to impact specific overflow points. As discussed in Section 3.2 of the NMC report, only one of the regulated industrial users is located in a CSO area: CSO-043. However, the other eight discharge wastewater to interceptors that flow to the Front Street and Spring Creek pump stations. There are permitted bypass CSOs at both pump stations (CSOs 002 and 003); therefore, these regulated industrial users are upstream of permitted CSOs. Five of the eight industrial users lie within suburban community collection systems. The assessment indicated there is not a concentration of non-domestic discharges within the combined sewer system Water Quality Standards CRW s water quality compliance objectives are discussed in the CD deliverable Water Quality Modeling Plan submitted to PADEP on July 27, Water quality standards for sediment, nutrients, dissolved oxygen, and bacteria are defined. Under the Clean Water Act (CWA), the PADEP Bureau of Point and Non-Point Source Management is responsible for establishing designated uses of each receiving water, establishing standards for measuring if these designated uses are attained, routinely assessing the attainment status of each receiving water, and, where necessary, defining requirements for achieving future attainment. The current attainment status of the waters receiving discharges from CRW s combined sewer system, according to the PADEP 2014 Pennsylvania Integrated Monitoring and Assessment Report, are documented in pages 3-6 of the CD deliverable LTCP Approach submitted to PADEP on December 23, 2014, summarized in Table 4-1. There were no changes in attainment status of the receiving waters from 2014 to 2016, as indicated in Appendix F of the draft 2016 Integrated Report Existing Water Quality Studies A review of existing water quality data is documented in the CD deliverable LTCP Approach submitted to PADEP on December 23, 2014, beginning on page 6. The review presents data from monitoring within reaches of the Susquehanna River and Paxton Creek receiving discharges from CRW s combined sewer system over the past decade or more. The document summarizes pertinent available data and published conclusions drawn from these data regarding CSO discharge characteristics, water quality, physical stream assessments, and biomonitoring for the Susquehanna River and Paxton Creek. A summary of this assessment follows. 4-2

44 Section 4 Characterization of Receiving Water Conditions Table 4-1: Attainment Status of Waters Receiving CRW Combined Sewer System Discharges Receiving Water Designated Use Cause / Constituent(s) Source Related to CSOs? TMDL Date Susquehanna Paxton Creek Fish Consumption PCBs Unknown No 2027 Potable Water N/A N/A N/A Attained Aquatic Life N/A N/A N/A Unassessed Recreation N/A N/A N/A Unassessed Aquatic Life DO/BOD CSOs Yes None Required Siltation / TSS Urban/Storm Sewers, Stream Erosion Potential 2008 Flow Variability Urban / Storm Sewers Potential None Required Habitat Alteration Urban / Storm Sewers Potential None Required Recreation Pathogens Unknown Potential 2025 Susquehanna River As part of the development of the 2005 LTCP, CSO discharges were monitored in Samples of CSO discharges were collected throughout overflow events to determine the combined sewer wastewater characteristics. Three CSO events between June and November 2003 were sampled at eight discharge locations selected based on estimated overflow volume and spatial distribution. The system-wide average event mean concentrations (EMC) for all storm events were calculated by determining the arithmetic average EMC for each parameter, shown in Table 4-2. Also presented in Table 4-2 are suggested EMCs for annual loading calculations, as documented in Volume 1 of the Final Report from the USEPA summarizing the results of the Nation-wide Urban Runoff Program (NURP). Published ranges of CSO EMCs shown in the table are based on a literature review. Table 4-2: Event Mean Concentrations (EMCs) of CSO Discharges to the Susquehanna River Parameter Susquehanna River System-Wide Average EMC (mg/l) NURP-Recommended EMCs for Annual Loading Calculations (mg/l) Published CSO EMC Ranges (mg/l) Total Settleable Solids 2.0 n/a n/a Total Suspended Solids BOD Total Nitrogen n/a Total Phosphorus (as P) Fecal Coliform (#/100 ml) 230,466 21, ,000,

45 Section 4 Characterization of Receiving Water Conditions Water quality monitoring was conducted at sample sites along the east, west, and center tracts of the Susquehanna River during three wet weather events in 2004 to determine the effect of CSO discharges on water quality. Fecal coliform, dissolved oxygen, ph, temperature, and turbidity were measured. Results indicated the formation of a fecal coliform plume in the River along the eastern shore adjacent to Harrisburg. Since background fecal coliform levels were determined to be low or non-detectable during dry-weather sampling, elevated fecal coliform levels during wet weather were attributed to CSO discharges. CSO discharges did not seem to have a significant impact on other parameters, however. Results from this sampling effort were used to calibrate and verify the 2005 LTCP in-stream water quality model. Additional sampling data to measure fecal coliform along the Susquehanna River was collected by PADEP between July and September Sampling locations included sites that were upstream and downstream of Harrisburg mostly adjacent to developed suburban neighborhoods, as well as six locations along the reach impacted by CRWs CSO discharges. The results for sites upstream, downstream, and within the reach near Harrisburg are listed in Tables 4-3, 4-4, and 4-5, respectively. Tables include whether precipitation occurred close to the sampling date, the number of sites sampled and how many exceeded the water quality standard concentration of 400 #/100 ml, and summary statistics. Table 4-3: PADEP Fecal Coliform Sampling Results for Locations Upstream of Harrisburg Sampling Date Precipitation On Sampling Date Within the Past 24 Hours Number of Samples Number Exceeding 400/100 ml Fecal Coliform Concentration (#/100 ml) Minimum Maximum Geometric Mean 7/23/2014 None None /24/2014 None Light /25/2014 None None /28/2014 None Heavy /29/2014 None Light , /5/2014 None None /6/2014 Trace Light /11/2014 None None /13/2014 None Light , /14/2014 None None , /15/2014 None None , /19/2014 None None /20/2014 None None /21/2014 None Light , /3/2014 None Trace

46 Section 4 Characterization of Receiving Water Conditions Table 4-4: PADEP Fecal Coliform Sampling Results for Locations Downstream of Harrisburg Sampling Date Precipitation On Sampling Date Within the Past 24 Hours Number of Samples Number Exceeding 400/100 ml Fecal Coliform Concentration (#/100 ml) Minimum Maximum Geometric Mean 7/28/2014 None Heavy , /5/2014 None None , /12/2014 Light Light /14/2014 None None , /19/2014 None None Table 4-5: PADEP Fecal Coliform Sampling Results for Locations in the Reach Near Harrisburg (Sampling Site IDs SUSQ_34 through 39) Sampling Date Precipitation On Sampling Date Within the Past 24 Hours Number of Samples Number Exceeding 400/100 ml Fecal Coliform Concentration (#/100 ml) Minimum Maximum Geometric Mean 7/29/2014 None Light /5/2014 None None /12/2014 Light Light /14/2014 None None /19/2014 None None The sampling locations included in Table 4-5 within the reach of the Susquehanna impacted by CRW s CSO discharges are located at various locations along the width of the river, including the east shore, west shore, and in the center, as shown in Figure 4-1. Results from these locations vary significantly. PADEP s assessment in the draft 2016 Integrated Report was that there are five distinct water columns from the east to the west shores, which do not mix, in the Susquehanna River around Harrisburg. CRW s CSOs are discharged into the water column along the east shore and do not impact recreation near City Island, which is reflected in the data. Table 4-6 shows the fecal coliform sampling results at the location along the east shore directly impacted by CRW s CSO discharges. The Water Quality Standards for fecal coliform are defined in the Specific Water Quality Criteria in paragraph 93.7 of the Pennsylvania Code: Fecal coliforms/ 100 ml During the swimming season (May 1 through September 30), the maximum fecal coliform level shall be a geometric mean of 200 per 100 milliliters (ml) based on a minimum of five consecutive samples each sample collected on different days during a 30day period. No more than 10% of the total samples taken during a 30-day period may exceed 400 per 100 ml. For the remainder of the year, the maximum fecal coliform level shall be a geometric mean of 2,000 per 100 milliliters (ml) based on a minimum of five consecutive samples collected on different days during a 30-day period. The sampling results in Table 4-6 indicate that the water column along the eastern shore was in violation of the Water Quality Standard at the time of the sampling. However, it should be noted 4-5

47 Section 4 Characterization of Receiving Water Conditions that the two sampling locations near the City Island recreation centers had geometric means of 27/100 ml and 37/100 ml for samples collected on the same days. Figure 4-1: Map of PADEP Fecal Coliform Sampling Locations Near Harrisburg Paxton Creek Table 4-6: PADEP Fecal Coliform Sampling Results East Shore Adjacent to Harrisburg (SUSQ_34) Sampling Date On Sampling Date Precipitation Within the Past 24 Hours Fecal Coliform Concentration (#/100 ml) 7/29/2014 None Light 900 8/5/2014 None None 220 8/12/2014 Light Light /14/2014 None None 380 8/19/2014 None None 200 Geometric Mean: Similar to CSO monitoring for locations along the Susquehanna River, four CSO outfalls discharging into Paxton Creek were monitored as part of the 2005 LTCP flow monitoring program. Sampling during CSO discharges during the same wet weather events between June and 4-6

48 Section 4 Characterization of Receiving Water Conditions November 2013 was used to determine the combined sewer wastewater characteristics as outlined in Table 4-7. These values represent the system-wide average EMC for each parameter. As in Table 4-2, NURP recommended EMCs and ranges of EMCs found from literature review are provided. Water quality monitoring during wet weather indicated that nutrient, CBOD, and sediment concentrations increase significantly under wet weather conditions. Table 4-7: Event Mean Concentrations (EMCs) of CSO Discharges to Paxton Creek Parameter Paxton Creek System- Wide Average EMC (mg/l) NURP-Recommended EMCs for Annual Loading Calculations (mg/l) Published CSO EMC Ranges (mg/l) Total Settleable Solids 2.0 n/a n/a Total Suspended Solids BOD Total Nitrogen n/a Total Phosphorus (as P) Fecal Coliform (#/100 ml) 384,480 21, ,000, Pollutants of Concern Table 4-8 identifies the pollutants of concern for the Susquehanna River and Paxton Creek associated with CSOs, identified based on the various water quality/stream attainability studies by PADEP and others, and from prior available water quality monitoring and modeling information. Further information is provided in the December 23, 2014 memorandum LTCP Approach page 18. Table 4-8: Pollutants of Concern Discharging from CRW s Combined Sewer System Pollutant of Concern Susquehanna River Paxton Creek Chesapeake Bay Sediment Bacteria Dissolved Oxygen / BOD Nitrogen / Phosphorus Sediment is identified as a pollutant of concern in Paxton Creek, but not the Susquehanna River. The 2008 Paxton Creek TMDL Report indicates that about 86 percent of the sediment concentration is attributed to stream erosion and the rest to wet weather discharges. Bacteria is a pollutant of concern in both receiving water bodies due to human health risks from pathogens during in-stream recreational activities. Elevated levels of bacteria are associated with CSO discharges and present a potential threat in areas of the Susquehanna used for recreation. No recreation occurs in Paxton Creek at this time. Oxygen-demanding substances (e.g., BOD, COD) that cause dissolved oxygen concentrations to fall below limits necessary to sustain aquatic life are considered a pollutant of concern in Paxton Creek. Per PADEP s 2012 Susquehanna River Study, which included water quality monitoring between June and August 2012, dissolved oxygen concentrations along the east transect of the 4-7

49 Section 4 Characterization of Receiving Water Conditions Susquehanna were less variable, indicating lower discharges of oxygen-demanding substances and/or higher aeration rates, resulting in few observed in-stream DO depletion events. Nitrogen and phosphorus loads must be reduced under the Pennsylvania Chesapeake Watershed Implementation Plan, and thus should be considered pollutants of concern for CSOs to both receiving water bodies. Existing levels of wet weather treatment achieved by CRW s combined sewer system, coupled with additional treatment achieved under the LTCP, will help achieve the targeted nitrogen load reduction of approximately 50 percent and the targeted phosphorus load reduction of approximately 40 percent. PADEP s May 2016 NDPES General Permit for Stormwater Discharges from small MS4s establishes minimum loading reductions of Chesapeake Bay pollutants of concern 10% for sediment, 5% for total nitrogen, and 3% for total phosphorus Priority and Sensitive Areas Due to the distribution of the 58 CRW outfalls along each receiving water and the relatively uniform characteristics of the receiving waters, there are not any Sensitive Areas as defined in the National CSO Policy in the receiving waters that would directly require more attention than others in evaluating LTCP options. Portions of the Susquehanna River are used for recreation, including fishing, boating, and swimming/wading. However, it should be noted that the primary points of direct contact (swimming and wading) within the Susquehanna River are located on City Island at the public beach, which is not susceptible to discharges from CRW s CSO outfalls due to the Susquehanna River s flow regime. Near-shore discharges to the Susquehanna do not migrate or disperse from the shore, as noted in the 2016 Pennsylvania Integrated Water Quality and Assessment Report, this results in five distinct water columns from the east to west shores in the Susquehanna River around Harrisburg, PA. These waters do not mix due to the Susquehanna River being relatively low and shallow. However, as part of the LTCP development process, CRW will develop a CSO LTCP implementation schedule that, among other criteria, gives higher priority to controlling CSOs to the Susquehanna River. Additional information is documented in the April 1, 2016 memorandum Sensitive Areas/Priority Areas in the Harrisburg Receiving Waters. 4.3 References LTCP Approach. Partial CD Deliverable. Submitted to PADEP December 23, Water Quality Modeling Plan. Partial Consent Decree Deliverable. Submitted to PADEP July 27, Sensitive Areas/Priority Areas in the Harrisburg Receiving Waters. Partial Consent Decree Deliverable. Submitted to PADEP April 1, Pennsylvania Integrated Water Quality Monitoring and Assessment Report. DEP Draft Pennsylvania Integrated Water Quality Monitoring and Assessment Report. DEP Water Quality Monitoring Data Analysis Report LTCP Attachment H. City of Harrisburg. August Results of the Nationwide Urban Runoff Program. Volume 1 Final Report. U.S. Environmental Protection Agency. December PADEP Susquehanna River Bacteria Sampling Report. Sent to Capital Region Water August 1, CRW Nine Minimum Control Plan, Version 3.0, August

50 Section 5 Description of Data Collection and Monitoring 5.1 Regulatory Context Capital Region Water (CRW) has previously developed documentation of the Initial Flow Metering and Monitoring Program Plan (IFMMPP) in response to a partial Consent Decree (CD) with the United States and PADEP. The IFMMP was submitted on July 1, 2013 and amended several times to address EPA/DEP comments. This section summarizes content that was previously developed and provides an update of the status of this process to satisfy Paragraph E(15) (a) through (f) of CRW s partial CD with the United States and PADEP: Initial Flow Metering and Monitoring Program Plan. CRW shall implement the final Initial Flow Metering and Monitoring Program Plan ( IFMMPP ), and in accordance with the IFMMPP shall complete the following activities in support of system characterization, hydrologic and hydraulic model ( H&H Model ) calibration, and LTCP development according to the schedule in the final IFMMPP: a. Map and inspect the condition of both the Combined and Separate Sanitary Sewer Systems, as described in Paragraphs 11(a)(ii) (v); b. Divide the Combined and Separate Sanitary Sewer Systems into sewersheds and catchments as described in Paragraph 11(a)(ii); c. CRW shall upgrade (repair, or replace, as necessary) the flow meters measuring flow coming from the satellite communities into the Combined Sewer System by December 31, CRW shall utilize the upgraded meters to monitor the flow contribution from the satellite communities at the four locations shown in the final IFMMPP for the pendency of this Consent Decree; d. Install and document the installation of at least six (6) continuously recording rainfall gauges appropriately located in the Harrisburg Sewer System area, and collect and maintain rainfall data for the pendency of this Consent Decree for purposes of the IFMMPP and to satisfy the requirements of Paragraph 11(g)(iv). CRW shall also procure Gauge Adjusted Radar Rainfall ( GARR ) data for the CRW service area, and shall continue to procure such data as necessary pursuant to Paragraph 11(g)(vi); e. Install flow monitoring devices on the major trunk sewers tributary to the thirteen (13) critical or key CSO outfalls in the Combined Sewer System identified in the final IFMMPP, and on the nine (9) interceptor sites identified in the final IFMMPP, monitor flow and collect data on both wet weather and dry weather flows consistent with the IFMMPP for the purposes of H&H Model Calibration and Validation (a minimum of twelve (12) months). Prepare and submit to Plaintiffs for review and comment quarterly technical memoranda documenting the results and quality of the flow monitoring data. If, following review of the second 5-1

51 Section 5 Description of Data Collection and Monitoring quarterly technical memorandum, Plaintiffs agree that the flow monitoring data being collected is of sufficient quality and extent to support H&H Model Calibration and Validation, CRW may plan to remove all CSO monitoring technologies installed pursuant to the IFMMPP at the conclusion of the planned monitoring period if no degradation in data quality occurs. If, following review of the second quarterly technical memorandum, Plaintiffs do not agree that the flow monitoring data being collected is of sufficient quality and extent to support H&H Model Calibration and Validation, CRW shall retain and continue to operate all CSO monitoring technologies installed pursuant to the IFMMPP until such time as CRW provides written justification of the sufficiency and extent of the flow monitoring data for the purposes of supporting H&H Model Calibration and Validation and Plaintiffs provide a written response to CRW affirming the sufficiency of the monitoring data. Under no circumstances shall CRW collect less than one full calendar year of monitoring data. 5.2 Summary of Initial Flow Metering and Monitoring Program Plan Capital Region Water previously developed an Initial Flow Metering and Monitoring Program Plan (IFMMPP) located in Appendix C, which divided the work effort into four phases: Phase I IFMMPP Development: CRW evaluated existing data, identified data gaps, reviewed the existing hydrologic and hydraulic (H&H) model, and, based upon available information and common practice for wet weather system evaluations and planning. The Initial Flow Metering and Monitoring Project Plan summarized the findings of Phase I and presented CRW s approach to Phase II. Phase I is provided in Section 2 of the IFMMPP found in Appendix C-1 of this report. The IFMMPP and Phase 1 were amended and documentation is provided in Appendix C-2 of this report. Phase II IFMMPP Implementation: CRW collected and evaluated the rainfall, flow, sewer system, and hydrologic data necessary to refine and validate the calibration of CRW s H&H Model. Phase II is summarized in the August 2015 Memo Phase 2 Monitoring Program, located in Appendix D and the current status is provided in Section 5.3 of this report. Phase III System Characterization: CRW applied the calibrated H&H model and collected data about the operation, maintenance, and structural integrity of the existing combined sewer system to characterize its performance, quantify existing CSO volumes and frequencies, optimize the performance of the existing combined sewer system, and document the implementation of the CSO Nine Minimum Controls and MS4 Minimum Control Measures. Phase III is addressed through the compilation of this Combined Sewer System Characterization Report. Phase IV Long-Term Control Planning: CRW will apply EPA s Integrated Municipal Stormwater and Wastewater Planning Approach Framework throughout Harrisburg, 5-2

52 Section 5 Description of Data Collection and Monitoring yielding a CSO LTCP that reduces CSOs and other sources of wet weather flow as necessary to address water quality issues. Phase IV will incorporate the findings of the previous phases ensuring a comprehensive process to support the Long-Term Control Plan alternatives analysis, and will be complete by April 1, Summary of Monitoring Status There are four categories of monitoring data that were collected and analyzed under the implementation of the IFMMPP for sewer system flow characterization under dry and wet weather conditions, and the calibration of the H&H model in support of the development of the Wet Weather Plan: Precipitation monitoring to quantify rainfall and snowfall over the CRW service area. Suburban community point of connection (POC) monitoring to quantify and characterize dry and wet weather flow conveyed by customer municipalities to the CRW system. Interceptor sewer monitoring to quantify and characterize dry and wet weather wastewater flow conveyed through the CRW system to the advanced wastewater treatment facility (AWTF). Major trunk sewer monitoring at CSO regulator structures to quantify and characterize hydrologic parameters throughout the CSS, with flow monitoring conducted on over monitoring flow of influent 70 percent of the CSS area. There are two categories of additional monitoring data that were collected and analyzed to provide needed information to develop the H&H model and develop a wet weather control plan: Separate sanitary catchment monitoring to quantify and characterize dry and wet weather flow from separate sanitary catchment areas within the CRW collection system. CSO outfall boundary condition monitoring, to provide the varying water surface elevations along the Susquehanna River (USGS gage ) and Paxton Creek (CRW stage monitors) that are required by the H&H models. There was one additional category of monitoring data that were collected as a requirement under the Partial Consent Decree: CSO Activation Monitoring Pilot Study (CAMP) monitoring at four representative CSO overflow weir structures to evaluate the feasibility and efficacy of alternative technologies to provide remote, real-time monitoring information regarding regulator status and any dry weather overflows Precipitation Monitoring CRW maintains a precipitation gauge network consisting of 8 tipping bucket rain gauges located throughout the service area. The gauge network records rainfall depths in 5-minute time-step intervals with a minimum recorded depth of 0.01 inches. All the gauges are heated to allow for 5-3

53 Section 5 Description of Data Collection and Monitoring accurate measurement of frozen precipitation events during winter. Hourly rainfall data are also collected from the two National Weather Service gauges located at the Capital City Airport and at the Harrisburg international airport. The network of heated CRW gauges was installed in August and September 2014 and will continue to collect data through the duration of the development and implementation of the CRW Wet Weather Plan. Additional information on the precipitation gauge network is provided in Section 2.1. The monitoring status is summarized in Table 5-1 and the gauge locations are provided in Figure 5-1. Table 5-1: Status of Precipitation Data Collection Gauge Number Gauge Location Data Collection Initiated Data Collection Status Data Analysis Status RG1 Koons Park 9/3/2014 Ongoing Ongoing RG2 Market Street 8/1/2014 Ongoing Ongoing RG3 CRW AWTP 8/1/2014 Ongoing Ongoing RG4 Swarta 9/5/2014 Ongoing Ongoing RG5 United Water 9/12/2014 Ongoing Ongoing RG6 Lower Paxton 9/9/2014 Ongoing Ongoing RG7 East Pennsboro 9/6/2014 Ongoing Ongoing RG8 Steelton 9/5/2014 Ongoing Ongoing Like any rain gauge network, the CRW system cannot quantify and characterize precipitation volumes and patterns that occur between the gauge locations. To characterize the natural spatial variability of rainfall over the CRW service area, gauge adjusted radar rainfall (GARR) data were obtained and used along with the gauge network data. In August, 2014, CRW contracted with a firm specializing in providing radar rainfall data, and monthly data submissions commenced in September. GARR precipitation data were provided in 5-minute intervals within a high-resolution pixel grid comprised of 1-km by 1-km cells. A total of 586 pixel cells define precipitation patterns over the CRW service area, including the suburban communities. The required radar data are produced by the National Weather Service (NWS) Next Generation Radar (NEXRAD) system and were obtained from the KCCX radar site located near State College, Pennsylvania, approximately 100 km from the City of Harrisburg. In the production of GARR, radar rainfall was bias corrected through comparison with rain gauge accumulations. The high-resolution, spatially distributed GARR data over the entire CRW service area were used to characterize the response of sewer collection systems to wet weather and calibrate the H&H models Suburban Community POC Monitoring The IFMMP identified the four points of connection where wastewater flows from the suburban community collection systems are conveyed to the CRW system. CRW installed and maintained flow monitors at each of these POC sites to quantify and characterize dry and wet weather flow from the suburban community separate sanitary sewer systems. The monitors collected and recorded redundantly monitored wastewater depth, monitored velocity, and calculated flow in 5-minute time-step increments. The monitoring locations are provided in Figure 5-2 and the monitoring status is summarized in Table

54 Section 5 Description of Data Collection and Monitoring Figure 5-1: Precipitation Monitoring Sites 5-5

55 Section 5 Description of Data Collection and Monitoring Figure 5-2: Suburban Community Point of Connection and Interceptor System Monitoring Sites 5-6

56 Section 5 Description of Data Collection and Monitoring Table 5-2: Status of Suburban Community POC Data Collection Monitor ID Pipe Diameter catchment Area (acres) Data Collection Initiated Data Collection Status Data Analysis Status M9 24 inches 847 8/01/2014 Ongoing Ongoing M13 42 inches 12,602 8/15/2014 Ongoing Ongoing M32 34 inches 6,716 8/14/2014 Ongoing Ongoing M inches 2,334 8/14/2014 Ongoing Ongoing Interceptor Monitoring The IFMMP identified 9 critical or key monitoring locations along the CRW interceptor system that would provide the necessary data to successfully quantify and characterize wastewater flow within the CRW system and provide the necessary data to calibrate the H&H model. The monitors collected and recorded redundantly monitored wastewater depth, monitored velocity, and calculated flow in 5-minute time-step increments. The monitoring locations are provided in Figure 5-2 and the monitoring status is summarized in Table 5-3. Table 5-3: Status of CRW Interceptor System Data Collection Monitor ID Interceptor System Pipe Diameter Data Collection Initiated Data Collection Status Data Analysis Status IS1 Front Street 36 inches 8/01/2014 Ongoing Ongoing FSI Front Street 42 inches 8/01/2014 Ongoing Ongoing PCI Paxton Creek 60 inches 8/01/2014 Ongoing Ongoing PCRI Paxton Creek 48 inches 8/13/2014 Ongoing Ongoing IS2 Paxton Creek 48 inches 8/21/2014 Ongoing Ongoing IS3 Paxton Creek 60 inches 8/22/2014 Ongoing Ongoing IS4 Paxton Creek 42 inches 8/18/2014 Ongoing Ongoing M250 Hemlock Creek 24 inches 8/01/2014 Ongoing Ongoing SCI Spring Creek 34 inches 8/13/2014 Ongoing Ongoing Combined Trunk Sewer Monitoring at CSO Regulator Structures Addendum #3 to the IFMMPP, dated December 18, 2014, documented the final monitoring sites selected for the combined trunk sewers at 13 CSO regulator structures, responding to EPA review of the IFMMPP and unacceptable hydraulic conditions detected during detailed field investigations that were conducted in association with monitoring equipment installation. The monitoring duration for each CSO monitoring site was 12 months to quantify and characterize seasonal variations in wastewater flow and monitor a sufficient number of storm events throughout the year. The monitoring equipment included two categories of sensors that collected and recorded data in 5-minute time-step increments. The first were used to successfully quantify and characterize wastewater flow from the tributary sewershed area into the CSO regulator chamber, used to characterize representative hydrologic parameters of the tributary sewersheds. The second provided the depths of CSO flows over the diversion weirs. The monitored data was used to calibrate the H&H model. The monitoring locations are provided in Figure 5-3 and the monitoring status is summarized in Table

57 Section 5 Description of Data Collection and Monitoring Figure 5-3 CSO Regulator Structure Monitoring Sites Figure 5-3: Combined Trunk Sewer / CSO Regulator Flow Depth Monitoring Sites 5-8

58 Section 5 Description of Data Collection and Monitoring Table 5-4: Status of CRW CSO Regulator Structure Data Collection Monitor ID Pipe Size [HxW / Diam. (in)] Sewershed Area (acres) Data Collection Initiated Data Collection Status Data Analysis Status CSO x /31/2014 Completed Completed CSO /04/2014 Completed Completed CSO /05/2014 Completed Completed CSO /31/2014 Completed Completed CSO x /23/2014 Completed Completed CSO x /25/2014 Completed Completed CSO x /22/2014 Completed Completed CSO /22/2014 Completed Completed CSO /01/2014 Completed Completed CSO x /30/2014 Completed Completed CSO x /06/2014 Completed Completed CSO x /28/2014 Completed Completed CSO /05/2014 Completed Completed Separate Sanitary Catchment Monitoring CRW successfully monitored 7 critical or key separate sanitary catchment areas within the CRW collection system, two (SSMH 2413 and SSMH-3023) considered part of the combined sewer system. The data provided the necessary data to successfully quantify and characterize separate sanitary system wastewater flow within the CRW system and provide the necessary data to calibrate the H&H model. The monitors collected and recorded redundantly monitored depth, monitored velocity, and calculated flow in 5-minute time-step increments. The monitoring locations are provided in Figure 5-4 and the monitoring status is summarized in Table 5-5. Table 5-5: Status of CRW Separate Sanitary Catchment Area Data Collection Monitor ID Pipe Size (inches) catchment Area (acres) Data Collection Initiated Data Collection Status Data Analysis Status M15A 18 dia /01/2014 Completed Completed SSMH dia /01/2014 Completed Completed SSMH dia /17/2015 Completed Completed SSMH dia /17/2015 Completed Completed SSMH dia /18/2015 Completed Completed SSMH dia /17/2015 Completed Completed SSMH dia /09/2015 Completed Completed CSO Outfall Boundary Condition Monitoring CRW obtained water surface elevation monitoring data from United States Geological Survey (USGS) gauge for the Susquehanna River. The gauge is located adjacent to the CRW service area, on City Island, and is shown on Figure 5-5. The USGS river monitor records river elevation data in 30-minute time-step increments. The slope of the river shore from the upstream to the downstream limits of the CRW service area was used to extrapolate the monitored gauge elevations to each of the CRW CSO outfall locations along the river. The data provided the necessary boundary condition data for the H&H model, and for the ongoing quantification of the frequency, duration and volume of CSO discharges within the CRW service area. 5-9

59 Section 5 Description of Data Collection and Monitoring Figure 5-4: Separate Sanitary Catchment Area Monitoring Sites 5-10

60 Section 5 Description of Data Collection and Monitoring Figure 5-5: Paxton Creek and Susquehanna River CSO Outfall Boundary Condition Monitoring 5-11

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62 Section 6 Description of Hydrologic, Hydraulic, and Water Quality Modeling 6.1 Regulatory Context Capital Region Water (CRW) has previously developed documentation of the hydrologic, hydraulic, and water quality models that are being developed to support development of the CSO LTCP in response to a partial Consent Decree (CD) with the United States and PADEP. The H&H Model Report (April 2016) describes the development and calibration of the H&H Model of CRW s conveyance system. This section also describes the extension of the H&H model into the major trunk sewers of CRW s collection system. Collectively, this section, supported by the previously submitted reports, is intended to satisfy Paragraph E(15) of CRW s partial Consent Decree (CD) with the United States and PADEP: g. Utilize rainfall and flow monitoring data collected pursuant to the IFMMPP to revise, calibrate, and validate the H&H Model of the Conveyance and Collection Systems using the EPA SWMM 5 modeling platform. The H&H Model shall specifically include the entire Conveyance System (i.e., each regulator, each CSO Outfall, each pump station, each interceptor) and Combined Collection System trunk sewers of 42-inch diameter or greater plus at least an additional ten (10) percent of the system for model continuity and/or that hydraulically impact known chronic Unauthorized Releases. The Parties understand that this effort will result in the explicit inclusion in the H&H Model of a total of at least fifteen (15) to twenty (20) percent of the Combined Sewer System as measured by feet of pipe, as well as all portions of the Separate Sanitary Sewer System specified by Paragraph 30(b). h. Following revision, calibration, and validation of the H&H Model of the Conveyance and Collection Systems, submit a Sewer System H&H Model Report to Plaintiffs for review and approval in accordance with the requirements of Section VI (Review and Approval of Deliverables) by April 1, The Sewer System H&H Model Report shall include at least the following components: i. Introduction 1. Background 2. Scope and Objectives 3. System Description ii. Sewer Model Refinement, Calibration, and Validation 1. Methodology 2. Hydraulic Model Refinement 6-1

63 Section 6 Description of Hydrologic, Hydraulic, and Water Quality Modeling 3. Flow Data Assessment 4. Dry Weather Flow Calibration, including quantitative and qualitative calibration criteria 5. Wet Weather Flow Calibration, including quantitative and qualitative calibration criteria 6. Model Validation The Water Quality Modeling Plan (August 2015) was prepared to describe how CRW plans to define the water quality benefits of its LTCP development. The Plan describes CRW s proposed approach to evaluate the water quality benefits of the proposed LTCP, satisfying Paragraph E(17) of the CD: Water Quality Modeling Plan. If CRW will utilize the Demonstration Approach in one or more Receiving Waters, then by August 1, 2015, CRW shall submit to EPA and PADEP a Water Quality Model Plan for review and approval pursuant to Section VI (Review and Approval of Deliverables), and shall implement the approved Water Quality Model Plan in accordance with the schedule included therein. For each water body in which the Demonstration Approach is to be used, the Water Quality Model Plan shall address: a. Water quality modeling software to be employed; b. Model configuration, including reaches to be modeled and segmentation and boundary conditions; c. Calibration and validation, including events and data to be employed, quantitative and qualitative calibration criteria, and utilization of H&H Model outputs; d. Use of the Water Quality Model to evaluate Typical Year in-stream conditions for each identified pollutant of concern; e. Schedule for model development and implementation, including integration into LTCP development consistent with other dates required pursuant to this Consent Decree. 6.2 Summary of CRW s Hydrologic & Hydraulic Model The hydrologic model represents the wastewater and surface runoff generated by all areas within CRW s CSS, while the hydraulic model represents CRW s conveyance system and trunk sewers. The Sewer System Hydrologic and Hydraulic Report (Appendix E) focused on the development, calibration and validation of the H&H model of the conveyance system. Since completion of the modeling report and CRW s major data collection effort to develop a GIS of its collection system, the model was extended into the collection system trunk sewers, as required by the partial Consent Decree, to support of this Combined Sewer System Characterization Report and the CSO Long Term Control Plan development, due April 1, The XP-SWMM hydraulic model developed to support preparation of the CSO LTCP in 2005 was converted into SWMM5 and used as the starting point to update and refine the conveyance system model. This model was then calibrated with the flow and rainfall data collected between September 2014 and November 2015 using the WaPUG calibration criteria. The calibrated 6-2

64 Section 6 Description of Hydrologic, Hydraulic, and Water Quality Modeling conveyance system/trunk sewer model was used to develop the typical year overflow statistics reported in Section 7 of this Report Model of CRW s Conveyance System The hydraulic model of the conveyance system consists of the following components: Interceptor system: upstream and downstream inverts, diameter or size, shape, depth of sediment were refined using data collected for CRW s GIS development program. Regulator and CSOs: physical parameters and the operational schedules were collected from field inspection and interviews with CRW Field Operations personnel. Pump Stations: Pump capacity, pump curves, wet well level time series and operational schedules were collected during preparation of CRW s Operation and Maintenance Manual Model of CRW Trunk Sewers According to the requirements of the Partial Consent Decree (CD)) Paragraphs E(15)(g), the hydraulic model was extended into the collection system trunk sewers, defined as 15 to 20 percent of the pipes within CRW s collection system meeting the following criteria (see Table 6-1 and Figure 6-1): All combined sewers 42 or greater. All separate sanitary sewers 18 or greater that drain into the combined sewer system, and Additional sewers necessary to represent the downstream portion of the collection system discharging to CSO regulators, including major flow split manholes within the collection system. Table 6-1: Characteristics of CRW s Collection/Trunk Sewer Model Features Characteristics Number of Catchments 482 Number of Pipes 2,148 Number of CSOs 59 Number of Wastewater Pumping 2 (Front Street and Spring Creek Pump Stations) Inflow from Suburban Communities 4 (M9, M13, M32, M167) Six Interceptor Systems: (1) Front Street Interceptor; (2) Paxton Creek Interceptor; (3) Paxton Relief Interceptor; (4) Spring Creek Interceptor; (5) Hemlock Creek Interceptor; (6) Asylum Run Interceptor 6-3

65 Section 6 Description of Hydrologic, Hydraulic, and Water Quality Modeling Trunk Sewers Figure 6-1: Interceptor and Major Trunk Sewer Model 6-4