Sanitary Sewer Flow Monitoring Study City of Grandville

Transcription

1 Sanitary Sewer Flow Monitoring Study City of Grandville Prepared for: City of Grandville Kent County, Michigan Report by: Moore & Bruggink Consulting Engineers Grand Rapids, Michigan March 214

2

3 Sanitary Sewer Flow Monitoring Study City of Grandville Table of Contents Page Number 1. EXECUTIVE SUMMARY BACKGROUND FLOW MONITORING PLAN...9 Methodology...9 Description of Equipment...9 Data Interpretation and Graphical Representation...9 Summary of Flow Monitoring Graphs...11 Flow Monitoring Areas of Concern...21 Methodology...22 Summary of Field Investigation Findings...23 Methodology...26 Summary of Laboratory Testing Findings SUMMARY AND RECOMMENDATIONS...27 Summary of Findings...27 Recommended Actions...32 APPENDICIES Appendix A: Study Area Map Appendix B: Flow Monitoring Data & Graphs Appendix C: Laboratory Testing Results Appendix D: Rainfall Records Appendix E: Grandville Backup Claims (April 213)

4

5 Sanitary Sewer Flow Monitoring Study City of Grandville 1. EXECUTIVE SUMMARY Moore & Bruggink, Inc. was contracted by the City of Grandville to conduct a flow monitoring study for portions of the Grandville sanitary sewer collection system. This study was conducted in response to the flood event which occurred between April 13 and April 2, 213. The purpose of this study was to identify possible locations of inflow and infiltration which were evident during flood conditions. On August 26, 213 at the regular City Council meeting Moore & Bruggink presented, and council approved, a plan to monitor the sanitary sewer flow and identify possible sources of inflow and infiltration in three key areas. The study areas are shown in Figure 1. Figure 1: Study Area Map Moore & Bruggink staff implemented a number of techniques to isolate the locations of inflow and infiltration into the sanitary sewer system. Thirteen flow monitors were installed throughout the study area to monitor flow within neighborhoods and monitor offsite flow entering the study areas. A field investigation was conducted to further identify the location of excess flow observed during flow monitoring. Laboratory testing was conducted by the Grandville CWP staff in an effort to help identify sources of excess flow. Three Study Areas were subdivided into neighborhoods and flow monitors were installed to locate sources of excess flow. Moore & Bruggink started installation of flow monitors on August 3, 213. The last monitor was installed on October 18, 213. Significant M&Bk March 214 1

6 Sanitary Sewer Flow Monitoring Study City of Grandville rain events were observed on September 9, October 5, October 31, November 6 and November 17, 213. All monitors were removed on November 18 and November 19, 213. The flow monitors consist of a sensor that is positioned in the sanitary sewer pipe and it measures and records flow depth and flow velocity. A data logging device, which is attached to the manhole steps, collects data sent by the sensor. All information is transferred from the logging device, to a laptop computer weekly for analysis. This data was used to identify areas of concern and excess flows. Typical flow monitoring equipment can be seen in Picture 1. Picture 1: Typical flow monitoring equipment. Flow monitoring module mounted on battery pack and Spring Ring insert with Area Velocity Sensor A field investigation was conducted on December 3, 213 in the areas of concern as identified by flow monitoring. During this investigation Moore & Bruggink staff along with City of Grandville Clean Water Plant staff visually observed flow conditions in the trunk sewer running adjacent to Buck Creek to the east of Ivanrest Avenue. Moore & Bruggink staff also visually observed flow along Willow Creek Drive, in Sub-Area 1.2 and in Sub-Area 3.2 (as denoted in Figure 1 located on Page 1). To complete these observations, the manhole covers were removed, flow rates in the sewers were observed and the condition of the manhole structure and any influent or effluent pipes was noted. The field investigation was conducted during a rain event in order to observe the sewer under wet weather conditions. This investigation verified runs of pipe where excess flow was entering the sanitary sewer system. M&Bk March 214

7 Sanitary Sewer Flow Monitoring Study City of Grandville Sanitary sewer samples were taken by Grandville Clean Water Plant staff at three locations (one at the outfall from each of the Study Areas) during two rain events and three dry weather days for a total of five tests at each location. If storm water is entering the sanitary sewer it will dilute the sanitary sewage and those changing conditions can be measured in the CWP laboratory. Unfortunately test results proved to be inconclusive. By conducting flow monitoring, field investigations, and laboratory testing, Moore & Bruggink was able to identify locations with minimal inflow or infiltration, locations with a low amount of inflow and infiltration and locations with a high amount of inflow and infiltration. All of Study Area 2 was found to have a minimal amount of inflow and infiltration. Moore & Bruggink observed a high amount of both inflow and infiltration in Study Area 1, and especially Sub-Area 1.2 (Choctaw area). Flow Monitor 3.2 recorded large amounts of excess flow from upstream of the study areas in conjunction with wet weather events. Additionally, a slight amount of inflow was observed in Sub-Area 3.1 (Wayburn area). Throughout our investigation, Moore & Bruggink was looking to determine if any portion of the sanitary sewer collection system was undersized, and if this wasn t the case, why did sanitary sewer backups occur. Our findings indicated that the collection system is properly sized to accommodate the anticipated sanitary sewer flow as well as a reasonable amount of inflow and infiltration (as is evident during the 5 rain event that was monitored on September 9, 213). Moore & Bruggink found sanitary sewer backups occurred as a result of exceptional hydro-geologic conditions resulting from extreme wet weather events. During the April 213 flooding the ground was saturated from prolonged wet weather, river levels were elevated from ongoing seasonal snow melt, and the Grand River basin received over 1 of rain over the course of 11 days. All of these factors caused the sanitary sewer to become inundated with an amount of storm water that could not be accommodated in the sanitary sewers. Under these conditions, pressures in the sanitary sewers rose to the point that some homes experienced basement flooding. To alleviate this problem, storm water sources need to be identified and flow diverted out of the sanitary sewer system to the storm sewer system. Based on the findings from the flow monitoring and field investigations, Moore & Bruggink has compiled a set of recommended actions. These actions include televising and smoke testing in selected areas to identify specific sources of inflow and infiltration, disconnecting sump pumps, disconnecting footing drains, disconnecting down spouts, raising and flood proofing manholes on the trunk sewer along Buck Creek east of Ivanrest Avenue and further investigating the source of excess flow outside of the current study areas. Table 1 outlines our findings and recommendations. M&Bk March 214 3

8 Sanitary Sewer Flow Monitoring Study City of Grandville Table 1: Findings & Recommendations M&Bk March 214 4

9 Sanitary Sewer Flow Monitoring Study City of Grandville 2. BACKGROUND Between April 8, 213 and April 19, 213 the Grand River Basin received nearly 1 of rain. This rain coupled with ongoing, seasonal snow melt resulted in significant flooding in both the Grand River and its tributaries. The flood level in the City of Grand Rapids made national news! Grandville experienced two separate flood events; the first resulted from high water levels in Buck Creek on April 18, 213 and the second resulted from high water levels in the Grand River on April 19, 213. In addition to severe surface flooding, excess flow was observed in the sanitary sewer system. Figure 2 shows locations of observed basement flooding that resulted from this rain event. It is important to note that no distinction was made between surface water entering basements and sanitary sewer backups into basements. Figure 2: Grandville 213 Reported Sewer Backup Map M&Bk March 214 5

10 Sanitary Sewer Flow Monitoring Study City of Grandville Moore & Bruggink, Inc. was contracted by the City of Grandville to conduct a flow monitoring study for portions of the Grandville sanitary sewer collection system. This study was conducted in response to the flood event which occurred between April 13 and April 2, 213. The purpose of this study was to identify possible locations of inflow and infiltration. On August 26, 213 at the regular City Council meeting Moore & Bruggink presented a plan to monitor the sanitary sewer flows in three key areas, which correspond to the areas where basement flooding was observed (see Appendix A: Study Area Map). Figure 3: Example Sources of Inflow and Infiltration Inflow is defined as water entering the sanitary sewer system through non-sanitary sewer connections, such as storm catch basins, roof drains and sump pumps. These connections will generally become apparent during wet weather events, resulting in increased flow during and after wet weather. In addition, inflow is generally characterized as having a greater peaking factor than infiltration, i.e. a more directly related flow increase from rainfall. An example of inflow can be seen in Figure 4 on page 7. Infiltration is defined as water entering the sanitary sewer system through sources such as leaking joints in sanitary sewer pipes, cracks in manholes, broken pipes and root intrusion. This water is generally groundwater and will be characterized as a base flow that is seen even during dry weather. Often, during wet weather events, infiltration volume increases gradually due to saturated soil surrounding the sanitary sewer. An example of infilatration can be seen in Figure 5 on page 7. M&Bk March 214 6

11 Sanitary Sewer Flow Monitoring Study City of Grandville Spike in Flow:.22 cfs before rain starts.7 cfs after rain starts Rain Event: 1.7 in/hr for 3 hours, 5 total rain received Figure 4: Example of Inflow. Note spike in flow resulting from 5 rain event on 9/9/ Homes, Infiltration Evident: Night time low flow ~.26 cfs Day time high flow ~.37 cfs 143 Homes, No Infiltration: Night time low flow ~.25 cfs Day time high flow ~.1 cfs Figure 5: Example of Infiltration during dry weather. The Mohave Court 8 FM 1.1 monitored 11 homes while the Yellowstone Drive 8 Flow Monitor 1.3 monitored 146 homes. Note that the flow in the Yellowstone Drive 8 is typical for a sewer without infiltration and base flow is much lower than the flow in the Mohave Court 8 where infiltration is evident. Yellowstone Drive should have more flow than Mohave Court based on the population served in each area. M&Bk March 214 7

12 Sanitary Sewer Flow Monitoring Study City of Grandville Based on the locations of reported basement flooding (Figure 2 on page 5), Moore & Bruggink installed thirteen sanitary sewer flow monitors in three areas beginning in late August 213. These areas included: 1. The neighborhood between Aaron Avenue and Wilson Avenue North of 4 th Street as well as between Canal Avenue and Aaron Avenue North of Blackfoot Drive (Study Area 1). 2. The neighborhood along North Big Springs Drive North of Shoshone Drive, Yellowstone Drive, Iris Drive, Apache Court, Tomahawk Drive, Oskalossa Drive North of Yellowstone Drive, Socorro Drive, Cheyenne Drive west of Oskalossa Drive, Pueblo Court, Algonac Drive and Earle Avenue (Study Area 2). 3. The neighborhood along Wayburn Avenue and Woodbine Avenue between 34 th Street and Prairie Street (Study Area 3). Each of these study areas was subdivided such that the location of inflow and infiltration could be more accurately identified. Each colored area on the map found in Appendix A: Study Area Map was directly monitored for excess flow. Detailed flow results of this monitoring can be found in Appendix B: Flow Monitoring Data & Graphs. M&Bk March 214 8

13 Sanitary Sewer Flow Monitoring Study City of Grandville 3. FLOW MONITORING PLAN Methodology The sanitary sewer system was divided into subsections to be monitored. Monitor locations can be seen in Appendix A: Study Area Map. In addition to the flow meters used to observe these subsections of the study area, additional flow meters were installed to observe the flow entering from upstream of the study areas. These additional monitors were used to determine if spikes in flow were caused by upstream inflow or infiltration. These monitors were installed during August, September and October of 213. All monitors were removed on November 18, 213 and November 19, 213 after quality rain events were observed at all locations. Monitors were placed in the upstream pipes in each of the selected manholes. A field measurement of the depth of flow in each pipe was taken and used to calibrate each monitor. The data recorders and batteries were then hung on the manhole steps and allowed to record data. Each week, the data from the monitors was downloaded to a laptop computer in the field and subsequently exported to Microsoft Excel to be analyzed, graphed, and compared to rainfall data. This method allowed for trends between rainfall events and excess flow in the sanitary sewers to be observed. Description of Equipment The flow monitors used for this survey were ISCO 215 Area Velocity Flow Modules with 2191 Battery Packs and Area Velocity Sensors Mounted to Spring Rings of varying size depending on pipe size. This equipment was used to directly measure flow depth and velocity. From these parameters, flow rate can be calculated. The flow monitors were set up to record the depth and velocity of the liquid in the pipe every 5 minutes. These monitors were installed from the ground level with a street level installation tool where manhole depth permitted. Data Interpretation and Graphical Representation Moore & Bruggink engineers downloaded flow data from the monitors to a laptop in the field on a weekly basis. This information was then exported to Microsoft Excel for analysis. All flow data can be found in Appendix B: Flow Monitoring Data & Graphs. This information has been graphed in order to interpret the raw data. Some of the installations were not able to record reliable velocity data. For analysis purposes, reliable level data has been used to analyze flow. To better compare varying sites, a normalized level has been used. This metric compares the actual level at any given time to the average level observed throughout monitoring. A normalized level of 1% indicates the average level where a normalized level of 2% indicates a level twice as high as the average level. Graphs were examined to find correlations between the rainfall events and the sewer levels in relation to the average level. Inflow manifests itself in sharp peaks directly following the start of a rain event. Because it takes additional time for water to travel through the soil structure, infiltration is generally indicated by a delayed, lower M&Bk March 214 9

14 Sanitary Sewer Flow Monitoring Study City of Grandville magnitude, longer duration response in sewer level. It should be noted that flow throughout all of the study areas follows a diurnal pattern with low flow at night and spikes in the morning (beginning of work day) and afternoon (end of work day). This can be seen in Figure 6. High Flow in Morning Higher Flow in Evening Low Flow at Night Lower Flow in Middle of Day (typical for residential areas) Figure 6: Example typical dry weather flow monitoring data showing diurnal flow pattern Rainfall events and rain fall intensity are shown on a separate y-axis from the flow level. An example rain event can be seen in the following Figure 7 on page 11. Rainfall is shown in light blue with the intensity (inches per hour) indicated on the right side y-axis. The level in the sewer is shown in dark blue with the depth (inches) indicated on the left side y-axis. Moore & Bruggink staff collected precipitation data for the entire study duration. This precipitation data was recorded at the Grand Rapids Gerald R. Ford International Airport and compiled by Weather Underground (a subsidiary of The Weather Channel Companies, LLC; also provides weather data for Google). M&Bk March 214 1

15 Sanitary Sewer Flow Monitoring Study City of Grandville Figure 7: Example wet weather event at Mohave Court. Note the spike in flow correlated to the rain event and the increased level for the following day. Data was scrubbed after entry into Excel to eliminate suspicious data before graphing. Erroneous data could include negative velocities or unobtainable high velocities. On rare occasions, bad level data was recorded. These were generally instances where debris was caught on the flow sensor. In order to correct for this, data points were linearly interpolated between reliable level data. Overall, the level data was highly reliable. In order to accurately compare flow for all times during monitoring, level data has been analyzed extensively. Summary of Flow Monitoring Graphs Graphs of monitor data are shown in Appendix B: Flow Monitoring Data & Graphs. The following is a summary of each monitoring location for all study areas based on interpretation for the graphical results. Refer to Appendix A: Site Map for monitoring locations. M&Bk March

16 Sanitary Sewer Flow Monitoring Study City of Grandville Study Area 1 Flow monitoring results in Study Area 1 show that a high level of inflow and particularly infiltration is added to sanitary sewer flows in this residential neighborhood. All of three of these sub-areas had flow data showing a high base flow in the sewers and sub area 1.2 and sub area 1.1 also showed evidence of inflow during wet weather events. Sewers in this neighborhood flowed at ½ full levels even in the middle of the night when minimal flow is expected from residential customers. This flow data indicates that footing drains, and sump pumps and possibly leaky pipe joints are allowing ground water as the primary component of normal daily sewer flows. There are a total of 259 homes in Study Area 1 which is notably less than the often used rule of thumb for 35 home capacity on an 8 inch diameter sanitary sewer. Figure 8: Map of Study Area 1 Mohave Court 8 sewer (Flow Monitor 1.1): This monitor was installed to observe the flow out of Study Area 1 and, specifically, the area bordered by Mohave Drive, Buck Creek, Wilson Avenue and Ponca Drive. Flow spikes were observed at this location during wet weather events, but these spikes can be attributed, at least in part, to upstream flows from sub-areas 1.2 and 1.3. High flow rates were specifically noted from Sub-Area 1.2 as observed from the Choctaw Drive 8 flow monitor. The sewer level in the Monitor 1.1 location never decreased substantially, even at night, this can be attributed to the level in the trunk sewer just downstream. M&Bk March

17 Sanitary Sewer Flow Monitoring Study City of Grandville Choctaw Drive 8 sewer (Flow Monitor 1.2): This monitor was installed to the residential neighborhood bordered by Pawnee Drive, Canal Drive, Blackfoot Drive and Mayaka Court. In this area a strong correlation between wet weather events and increased sanitary sewer levels was observed (see Figure 9). In addition, the diurnal night time levels never substantially decreased, which could indicate infiltration. Because of these observations, a field inspection was conducted in the area. Figure 9: Example wet weather event at Choctaw Drive 8. Note the spike in level correlated to the rain event and the sustained increase in level days after the rain event. Aaron Avenue 8 sewer (Flow Monitor 1.3): This monitor was installed to record the area bordered by Aaron Avenue, Wilson Avenue, 38 th Street and 4 th Street. This service area is residential with the exception of Grandville West Elementary School. While no spikes in flow were observed during wet weather events, the level in the sewer never decreased substantially at night (the minimum night time level was usually around 3.5 flow depth). This could indicate infiltration and a follow up field inspection was conducted. M&Bk March

18 Sanitary Sewer Flow Monitoring Study City of Grandville Study Area 2 Study Area 2 showed the least amount of infiltration and inflow for all of the study areas. While there is evidence of some I/I in this neighborhood, it is best for the City to pursue further action in areas where efforts will yield larger returns by way of flow reduction. The pipes in these areas are adequate for normal flows including typical wet weather events. Figure 1: Map of Study Area 2 North Big Spring Drive 1 sewer (Flow Monitor 2.1): This monitor was installed to observe the sanitary sewer flow from the homes along North Big Spring Drive, Earle Avenue and Yellowstone Drive west of Earle Avenue. This monitor directly measured the flow out from the entire Study Area #2. The flow for this neighborhood was determined by comparing the total flow out from Area #2 to the flow from the Iris Drive 8 flow monitor and the Yellowstone Drive flow monitor. No excess flow was observed during wet weather events, but the sanitary sewer level did increase during rain events. This indicated that the level in the sewer in North Big Springs at Wilson Avenue is affected by the flow in the trunk sewer in Wilson Avenue. Iris Drive 8 sewer (Flow Monitor 2.2): This monitor was installed to observe the flow from the homes along Iris Drive. This was one of the smaller areas monitored (33 upstream homes) and the observed flow was much lower than any other neighborhood. Flow monitoring indicated that this neighborhood does not have a problem with inflow or infiltration. Consequently, there was no evident correlation between wet weather events and excessive flow in the sanitary sewer. Yellowstone Drive 8 sewer (Flow Monitor 2.3): This monitor was installed to observe the flow from the homes along Yellowstone Drive East of Earle Avenue, Apache Court, M&Bk March

19 Sanitary Sewer Flow Monitoring Study City of Grandville Algonac Drive, Socorro Drive, Pueblo Court, Cheyenne Drive and Tomahawk Drive. During wet weather events there was a slight increase in flow (~.4 cfs additional flow, see Figure 11). Flow monitoring indicated that this neighborhood does not have a significant problem with inflow or infiltration. Figure 11: Example wet weather event at Yellowstone Drive 8. Note the slight increase in flow (an additional ~.4 cfs) correlates to a significant rain event. This was not observed during other, smaller, rain events. Determined to be minimal impact area. M&Bk March

20 Sanitary Sewer Flow Monitoring Study City of Grandville Study Area 3 Evidence of both inflow and infiltration are indicated by flow data from this area. Televising sanitary sewers in this neighborhood immediately after a good rain would provide the best opportunity to observe sump pump discharges into the system. Figure 12: Map of Study Area 3 Wayburn Avenue 8 sewer (Flow Monitor 3.1): This monitor was installed to observe the flow from the homes along Wayburn Avenue. This is a relatively small service area and flow followed a very distinct diurnal pattern. During wet weather events the flow rate increased dramatically and remained elevated for some time (see Figure 13 on page 17). This indicates that there is both inflow and infiltration in this area. M&Bk March

21 Sanitary Sewer Flow Monitoring Study City of Grandville Figure 13: Flow monitoring data from wet weather event at Wayburn Avenue. Note the prolonged increase in flow resulting from a small rain event (.5 in/hr for 24 hours). Woodbine Avenue 12 sewer (Flow Monitor 3.2): This monitor was installed to observe the flow from along Woodbine Avenue and Prairie Street. Flow monitoring data did not conclusively indicate inflow or infiltration. During three rain events there was a sharp, short term, spike that seemed to indicate inflow (possibly in the form of a sump pump). This was not observed during every rain event and further investigation is required to determine if any corrective actions should be taken. M&Bk March

22 Sanitary Sewer Flow Monitoring Study City of Grandville Outlying Monitors The outlying monitors indicated that excess flow is entering the study areas from adjacent areas, especially through the Ivanrest Avenue 16 sewer. Short term spikes in flow were observed during wet weather events in the Wilson Avenue 15 sewer. Additionally, Moore & Bruggink observed a low amount of inflow or infiltration during wet weather events entering the study area from the Ivanrest Avenue 12 sewer. Figure 14: Study Area Map Indian Springs 21 sewer (Flow Monitor.1): This monitor was installed to observe the flow out of all the Study Areas and to see if the trunk sewer ever became surcharged. As expected, there were spikes in flow during wet weather events but the sewer never became surcharged through the flow monitoring period. Pipes are adequately sized for normal flow conditions. Additional flow monitoring should be done upstream of the current study areas to further determine areas of inflow and infiltration into the sanitary sewer system. A sewer becomes surcharged when it can no longer accommodate the amount of flow that it is receiving. Upstream water levels can rapidly increase when a sewer becomes surcharged which, in severe cases may result in backing up into manholes, private sewer laterals and even basement flooding. While Moore & Bruggink observed large rain events during flow monitoring (up to approximately 5 in one day), there were no rain events that replicated the flooding experienced in the spring of 213. During this flood event the ground was saturated from prolonged wet weather, river levels were elevated from ongoing seasonal snow melt, and the Grand River basin received over 1 of rain over the course of 11 days. This culmination of events created excessive inflow and infiltration in the Grandville sanitary sewer collection system, possibly resulting in the M&Bk March

23 Sanitary Sewer Flow Monitoring Study City of Grandville trunk sewer becoming surcharged. The trunk sewers have sufficient capacity to accommodate normal sanitary sewer flow and the excess flow resulting from a 5 rain event. Sewer backups experienced during the flooding in April 213 were a result of exceptional flow conditions resulting from extreme wet weather events, not a lack of wastewater capacity in the collection system. Wilson Avenue 18 sewer (Flow Monitor.2): This monitor was installed to observe the flow from Study Area 3 (and upstream) as well as the flow from the neighborhood to the west of Study Area 3. There were spikes in flow during wet weather events which can be explained with the spikes in flow upstream from Study Area 3. This monitor was also used to see if the trunk sewer ever became surcharged, which was not observed during the monitoring period. Wilson Avenue 15 sewer (Flow Monitor.3): This monitor was installed to observe the flow from the trunk sewer that services the area to the south of Study Area 2. This area had fairly consistent flow, even during wet weather events (refer to Figure 15). There were some spikes in flow rate, primarily during wet weather events, characterized by a very short term increase in flow rate (as a result of an increase in velocity) without a corresponding increase in sewer level. These spikes are likely the result of upstream conditions and require further investigation to determine their source. Figure 15: Example wet weather event at Wilson Avenue 15. Note the spikes in flow correlated to the rain events. M&Bk March

24 Sanitary Sewer Flow Monitoring Study City of Grandville Ivanrest Avenue 16 sewer (Flow Monitor.4): This monitor was installed to observe flow entering Study Area 3 from the trunk sewer that travels along Buck Creek to the east of Ivanrest Avenue. This line services everything south of 34 th Street between Ivanrest Avenue and the eastern city limit. Flow monitoring data from October 31, 213 and November 6, 213 shows that a small rain event resulted in excessive flow from this line (this can be seen in Figure 16). Because of this observation, a field investigation was conducted to attempt to locate a specific source of the excess wet weather flow. Figure 16: Example wet weather event at Ivanrest Avenue 16. Note the spikes in flow correlated to the rain events of October 31, 213 and November 6, 213. A small rain event results in excessive infiltration. Ivanrest Avenue 12 sewer (Flow Monitor.5): This monitor was installed to observe the flow entering Study Area 3 from the neighborhoods to the south and east of Study Area 2. During wet weather events, there was a slight increase in flow rate and sewer level, indicating a small amount of inflow or infiltration. M&Bk March 214 2

25 Sanitary Sewer Flow Monitoring Study City of Grandville Flow Monitoring Areas of Concern The flow monitoring data shows that significant infiltration is present in Study Area 1. This is especially apparent when observing the Choctaw Drive 8 flow monitor where overnight levels rarely decrease to less than approximately 4. Study Area 2 showed no significant signs of inflow or infiltration, which is to be expected in this area with predominantly newer sewers and construction. Study Area 3 has significant inflow and infiltration along Wayburn Avenue and appears to have inflow along Woodbine Avenue. The most significant source of excess flow did not come from within any of the Study Areas but, instead, from upstream from Study Area 3. While flow monitoring and field investigations revealed the source of some of this excess flow, further investigation is required to identify the exact source location of the observed inflow and infiltration. For more information on the excess flow from upstream of Study Area 3, please refer to the flow data from the Ivanrest Avenue 16 sewer (Flow Monitor.4) and the flow data from the Ivanrest Avenue 12 sewer (Flow Monitor.5) starting on page 18 as well as the field investigation information starting on page 22. M&Bk March

26 Sanitary Sewer Flow Monitoring Study City of Grandville 5. FIELD INVESTIGATION Methodology Areas of concern were identified based on flow monitoring results. These included Study Area 1 and the area upstream from Study Area 3. Because Buck Creek runs adjacent to the cross county sewer upstream from Study Area 3 it was hypothesized that water from Buck Creek could be entering the sewer system. This section of cross country sewer as well as the sewer servicing the neighborhood off of Willow Creek Drive was inspected during a rain event. Figure 17: Field Investigation Map To complete this field investigation Moore & Bruggink staff along with City of Grandville Clean Water Plant staff visually observed flow conditions in the trunk sewer running adjacent to Buck Creek to the east of Ivanrest Avenue. Moore & Bruggink staff also visually observed flow along Willow Creek Drive, in Sub-Area 1.2 and in Sub-Area 3.2. To complete these observations, the manhole covers were removed, flow rates in the sewers were observed and the condition of the manhole structure and any influent or effluent pipes was noted. The field investigation was conducted during a rain event on December 3, 213 in order to observe the sewer under wet weather conditions. This investigation verified runs of pipe where excess flow was entering the sanitary sewer system. Moore & Bruggink has identified specific locations of inflow and infiltration through a field investigation. These areas include the section of sewer between Chickasaw Court and Pawnee Drive along Blackfoot Drive, Basswood Drive to the south of Willow Creek and manholes along Buck Creek, which may become submerged during flooding events M&Bk March

27 Sanitary Sewer Flow Monitoring Study City of Grandville along Buck Creek. Other sources of infiltration likely exist, but these were the locations identified during the field investigation. Summary of Field Investigation Findings Cross Country Sewer Along Buck Creek: Excess flow as observed entering Study Area 3 from the 16 cross country sewer line that runs adjacent to Buck Creek East of Ivanrest Avenue. The manholes along this line were inspected to try to pinpoint where the excess flow was entering the system. All of the manholes were found to be in good condition (see Picture 2) and no excess flow was observed coming from this area. Some of the manholes were quite low and could become flooded if Buck Creek floods significantly (such as during the flooding experienced in the spring of 213). Picture 2: Cross country sewer along Buck Creek. No visual signs of infiltration present. Willow Creek Neighborhood: The Willow Creek neighborhood was investigated after no additional flow was discovered coming from the cross country sewer along Buck Creek. The investigation started at the manhole where the Willow Creek Neighborhood connects to the 16 Cross Country Sewer and worked west along Willow Creek. High flow was observed coming from Basswood Drive while at the intersection of Willow Creek and Basswood Drive. Normal, low flow was observed at the next upstream manhole south along Basswood Drive. This would indicate that storm water was entering the system between these two manholes (highlighted in red in Figure 18 on page 24). M&Bk March

28 Sanitary Sewer Flow Monitoring Study City of Grandville BASSWOOD DR. Figure 18: Cross Country Sewer and Willow Creek Neighborhood. High flow observed along highlighted line in Basswood Drive. Low manhole along Buck Creek identified. Choctaw Drive 8 Area: The inspection for this area started at the intersection of Choctaw Drive and Mohave Drive and worked upstream to identify the source of excess flow entering the sanitary sewer system. High flow was observed at the intersection of Pawnee Drive and Blackfoot Drive but low flow was observed upstream one manhole at the intersection of Blackfoot Drive and Chickasaw Drive. This would indicate that storm flow is entering the sanitary sewer system in the section (identified in Figure 19 on page 25). M&Bk March

29 Sanitary Sewer Flow Monitoring Study City of Grandville Figure 19: Choctaw Drive 8 Neighborhood. High flow observed along highlighted line in Blackfoot Drive. Woodbine Avenue 12 Area: The Woodbine Avenue neighborhood was examined in the same fashion as the previously described neighborhoods. The investigation started at 34 th Street and Woodbine Avenue and worked north to Prairie Street. During this rain event, no excess flow was observed. M&Bk March

30 Sanitary Sewer Flow Monitoring Study City of Grandville 6. LABORATORY TESTING Methodology If storm water is entering the sanitary sewer it will dilute the sanitary sewage. This should be apparent when comparing BOD readings from samples taken during wet weather events to those taken during dry weather events (no storm water present). Samples were taken by Grandville Clean Water Plant staff at three locations (outfall of each Study Area as depicted in Figure 2) during two rain events and during three dry weather days. CWP staff tested these samples for ph, phosphorus, ammonia, Biochemical Oxygen Demand & Carbonaceous Biochemical Oxygen Demand (BOD/CBOD) and Chemical Oxygen Demand (COD). Complete test results can be found in Appendix C: Laboratory Testing Results. Figure 2: Sampling Location Map Summary of Laboratory Testing Findings Unfortunately, test results proved to be inconclusive. Because the observed areas are relatively small and the parameters being tested for are highly variable no definitive conclusions about inflow or infiltration could be drawn. Many factors can affect the values of the parameters tested. Some of these factors include the time of day that testing occurred (due to diurnal flow pattern) and sanitary sewer use patterns. In addition, if significant inflow is consistently present, as is indicated by flow monitoring in Study Area 1, dry weather events may in fact contain significant storm water and ground water. M&Bk March

31 Sanitary Sewer Flow Monitoring Study City of Grandville 7. SUMMARY AND RECOMMENDATIONS Summary of Findings Moore & Bruggink conducted extensive flow monitoring on three Study Areas in the Grandville neighborhoods west of Ivanrest surrounding Buck Creek. This flow monitoring provided good flow data indicating how the sanitary sewer system functions in both dry conditions and during wet weather events. After flow monitoring was conducted and analyzed, potential areas of concern were identified and field investigations were conducted. Field investigations identified specific areas where inflow or infiltration were entering the sanitary sewer collection system. Additionally, laboratory testing was conducted on the sanitary sewage leaving each of the three Study Areas. This testing proved to be inconclusive. Flow Monitoring Thirteen flow monitors were placed in the area boarded by Prairie Street, Ivanrest Avenue, 4 th Street and Canal Avenue (see Appendix A: Study Area Map). Based on reported sewer backup locations, three study areas were selected. These Study Areas were subdivided to better understand the locations where inflow and infiltration were entering the sanitary sewer system. Flow monitoring showed that Study Area 1 had consistently higher than expected flows at all times, which is indicative of infiltration. This was especially apparent in the area monitored by the Choctaw Drive 8 flow meter. Flow levels in this area rarely dropped below approximately 4 (1/2 full pipe), even during the night. This infiltration is more indicative of groundwater entering the sanitary sewer system (as opposed to storm water which would be more prevalent during wet weather events). Very little inflow or infiltration was recorded in Study Area 2. Based on flow monitoring results, it appears that this portion of the Grandville collection system has very little infiltration and no observed inflow. A negligible amount of infiltration was observed at the Yellowstone Drive 8 flow monitor. There were two flow monitors placed in Study Area 3. The Wayburn Avenue 8 sewer flow monitor indicated inflow and infiltration along Wayburn Avenue. This was different than the excess flow observed in Study Area 1. In this case, flow returned to an acceptable level within a day of the end of a rain event. This indicates that storm water is slowly infiltrating the sanitary sewer system, possibly through cracks in pipes or manholes, or through floor drains in basements. The Woodbine Avenue 12 sewer flow monitor indicated inflow during wet weather events in the form of very short term flow spikes. This is indicative of sump pumps turning on and off. In addition to these three Study Areas, monitors were placed on sanitary sewer lines entering or leaving the Study Area. These were placed to determine if flow from outside the Study Area was contributing to flooding within the Study Areas. The Ivanrest Avenue 16 sewer flow monitor data indicated that significant inflow and infiltration was M&Bk March

32 Sanitary Sewer Flow Monitoring Study City of Grandville entering the Study Area from the 16 trunk sewer that runs along Buck Creek. Additionally, the Ivanrest Avenue 12 flow monitor indicated significant inflow and infiltration entering the Study Area from the trunk sewer running south along Ivanrest. The Wilson Avenue 15 flow monitor indicated that the 4 th Street Lift Station pumped additional water into the study area during wet weather events. A summary of our findings and recommended actions can be found in Table 2. Throughout the flow monitoring phase of our study no trunk sewers became surcharged. If a trunk sewer were to become surcharged, upstream water levels could rapidly rise, which may result in basement flooding in severe cases. The largest rain event that Moore & Bruggink observed occurred on September 9, 213 when Grandville received approximately 5 of rain over approximately 3 hours in the early morning. In fact, no basement flooding was reported in conjunction with the September 9 th rain event. Moore & Bruggink found that the trunk sewers are sized appropriately to handle the anticipated sanitary sewer flow from the service areas as well as a reasonable amount of I/I resulting from aging infrastructure. Sewer backups experienced during the flooding in April 213 were a result of exceptional hydrogeologic conditions resulting from extreme wet weather events, not a lack of wastewater capacity in the collection system. M&Bk March

33 Sanitary Sewer Flow Monitoring Study City of Grandville Table 2: Findings & Recommendations M&Bk March

34 Sanitary Sewer Flow Monitoring Study City of Grandville Field Investigation Figure 21: Field Investigation Map. Locations of field investigation are identified with a magenta line. The areas of concern identified through flow monitoring were further inspected to more accurately determine the locations of inflow and infiltration. A field investigation of Study Area 2 was not conducted because no areas of concern were identified at this location during the flow monitoring portion of our investigation. By visually observing flow in manholes Moore & Bruggink determined that the section of sewer along Blackfoot Drive between Chickasaw Court and Pawnee Drive contributes a significant amount of infiltration to the sanitary sewer system in Study Area 1. Field investigations in Study Area 3 did not identify the location of inflow or infiltration. The increased flow on Woodbine Avenue was indicative of sump pumps turning on and off. This could come from any or all of the homes in the area. During the field investigation Wayburn Avenue did not seem to have excessive flow. The field investigation was conducted during a light rain event, which may not have provided sufficient rain to cause excess flow along Wayburn Avenue. When investigating the excess flow observed at the Ivanrest Avenue 16 flow meter Moore & Bruggink staff determined that the trunk sewer along Buck Creek would not contribute inflow unless Buck Creek flooded to the point that it overflowed its banks. If this were to occur, several manholes could be in jeopardy of becoming submerged, which would result in water from Buck Creek entering the sanitary sewer collection system. Additionally, excessive flow was observed entering the sanitary sewer system between the intersection of Willow Creek & Basswood Drive and the next manhole south on Basswood Drive. M&Bk March 214 3

35 Sanitary Sewer Flow Monitoring Study City of Grandville Laboratory Testing Clean Water Plant staff collected samples at three locations each on five separate days. Two sets of samples were collected during rain events and three sets of samples were collected during dry weather events. Because rain water should dilute sanitary sewage, Moore & Bruggink predicted the samples would show lower levels of BOD during rain events where infiltration was present. From the flow monitoring and field investigations Moore & Bruggink determined that Study Area 1 and Study Area 3 both have some amount of inflow and infiltration. Unfortunately, laboratory testing proved to be inconclusive and no conclusions regarding inflow and infiltration could be drawn from the results. M&Bk March

36 Sanitary Sewer Flow Monitoring Study City of Grandville Recommended Actions Based on the findings from the flow monitoring and field investigations, Moore & Bruggink compiled a set of recommended actions. These actions are outlined in Table 3. Table 3: Recommended Actions Televising: Televising should be conducted to help pinpoint sources of inflow and infiltration. Televising can be conducted by Clean Water Plant staff and analyzed by Moore & Bruggink staff. This investigation will show the condition of the sanitary sewer system and identify defects that can lead to infiltration (roots, cracks, joint separation, etc.) and inflow (storm sewer cross-connections). This work can be conducted under the City s current Stormwater, Asset Management, and Wastewater (SAW) Grant and is eligible for reimbursement from the State of Michigan. If a sump pump, footing drain, or roof downspout is tied into a home s sewer lateral, the cross connection will not be directly observed, but an increased flow may be visible through televising the main line sewer. Televising should be conducted by Clean Water Plant staff during the spring when the water table is elevated. An elevated water table will help Moore & Bruggink staff identify sources of infiltration that may not be apparent when the water table is lower. Televising should be conducted along Blackfoot Drive between Chickasaw Court and Pawnee Drive, along Basswood Drive South of Willow Creek and along both Wayburn Avenue and Woodbine Avenue between 34 th Street and Prairie Street. Excess flow was observed in all of these locations during field investigations. This recommendation should be implemented in the short term. Televising should also be conducted along Aaron Avenue and the streets between Aaron Avenue and Wilson Avenue. Flow data indicates that the level in this area did not M&Bk March

37 Sanitary Sewer Flow Monitoring Study City of Grandville decrease substantially during night time flow. This would indicate some level of infiltration. Televising here should be implemented in the short term. Moore & Bruggink also recommends a televising schedule be created to continue to monitor the collection system and ensure that storm water is not entering the sanitary sewer system. This televising schedule should be incorporated into the City s Asset Management Plan, which will be created as part of the current SAW Grant. This schedule should divide the City into sections that will be monitored over multiple years. By continuing to televise the collection system, the City will be able to identify possible new cross connections. Moore & Bruggink recommends that this plan is continuously implemented over multiple years. Smoke Testing: Smoke testing should be conducted along Blackfoot Drive between Chickasaw Court and Pawnee Drive, along Basswood Drive South of Willow Creek and along both Wayburn Avenue and Woodbine Avenue between 34 th Street and Prairie Street. Based on the amount of excess flow observed in these locations, it is possible that roof downspouts are tied in to the sanitary sewer. This would be identified through smoke testing. If such testing is to be conducted, residents should be notified ahead of time to avoid undue confusion. Moore & Bruggink recommends that this work is completed in the short term. Upstream Inflow & Infiltration: It should be noted that while inflow and infiltration has been identified in the Study Areas, extensive excess flow is entering this area from upstream locations. Moore & Bruggink recommends a further investigation into the upstream sources of inflow and infiltration. When the trunk sewers surcharge due to excess flow upstream, the sanitary sewer in the neighborhoods studied are unable to transport sewage out of the study area, which could cause sanitary sewer backups. To solve the problems experienced in the Study Areas upstream sources of inflow and infiltration must be eliminated. Raise and Flood Proof Manhole Castings: Moore & Bruggink found that some of the manholes along Buck Creek to the East of Ivanrest may become submerged during flooding events. When these become submerged, storm water can enter the sanitary sewer collection system. Moore & Bruggink recommends that these casting be raised to approximately 2 above grade and have flood resistant castings installed. This work should be completed in the short term. Inform Residents of their Responsibilities: Moore & Bruggink recommends that a series of letters be sent to residents to help inform them of their responsibilities to minimize the amount of storm water entering the sanitary sewer collection system. The first letter in this series should be a general informative letter sent to all City residents and emphasize the fact that footing drains, down spouts and other storm water connections should not be directed to the sanitary sewer. In addition, this letter should inform residents that the City is investigating sources of inflow and infiltration throughout the City. The second letter in this series should be a targeted letter sent to residents in Study Area 1, Study Area 3, and the neighborhood off of Willow Creek and inform them that M&Bk March

38 Sanitary Sewer Flow Monitoring Study City of Grandville inflow and infiltration has been observed in their area. This letter should stress that if a home has an illicit storm water connection the homeowner should eliminate the connection by rerouting the connection to the storm sewer. Both of these letters should be sent out promptly. A third letter should be sent out after televising, smoke testing and any other exploratory work has been conducted. This letter should be sent to residents that have a confirmed storm water connection to inform the resident they have an illicit connection that should be disconnected. It should also inform the resident that corrective actions may be taken by the City if the connection is not repaired. These corrective actions could be in the form of a surcharge to the resident or a repair conducted by the City which will be back charged to the resident. M&Bk March

39 Appendix A: Study Area Map M&Bk March 214

40

41 AREA 1 = 259 HOMES SUB-AREA 1.1 = 11 HOMES SUB-AREA 1.2 = 56 HOMES SUB-AREA 1.3 = 93 HOMES AREA 2 = 236 HOMES SUB-AREA 2.1 = 6 HOMES SUB-AREA 2.2 = 33 HOMES SUB-AREA 2.3 = 143 HOMES AREA 3 = 12 HOMES SUB-AREA 3.1 = 36 HOMES SUB-AREA 3.2 = 66 HOMES SUB-AREA 3.1 SUB-AREA 3.2 O N R T H SCALE: 1" = 65' SUB-AREA 2.1 SUB-AREA 2.2 SUB-AREA 1.2 SUB-AREA 1.1 SUB-AREA 2.3 SUB-AREA 1.3 DATE: MARCH 214 SANITARY SEWER COLLECTION EVALUATION PHASE I STUDY AREAS CITY OF GRANDVILLE, KENT COUNTY, MICHIGAN MOORE BRUGGINK, INC. C o n s u l t i n g E n g i n e e r s 22 Monroe Avenue N.W. Grand Rapids, Michigan Phone: (616) Web:

42

43 Appendix B: Flow Monitoring Data & Graphs M&Bk March 214

44 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Indian Springs Drive 21" (Flow Monitor.1) 25 2 No strong correlation between level and flow rate. Flow rate data is sporadic and not reliable. Level data follows a diurnal pattern and is reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 9/13/13 9/23/13 1/3/13 1/13/13 1/23/13 11/2/13 11/12/13 Date

45 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Indian Springs Drive 21" (Flow Monitor.1) Approximately 5" or rain was received on 9/9/13. This rain event resulted in increased flow in the Indian Springs Drive 21" trunk sewer. Even during this large rain event the trunk sewer did not become surcharged, reaching a maximum level of ~14". The trunk sewer never became surcharged during flow monitoring. It is important to note the sharp spike in level followed by a maintained increase in level for days after the rain event. These are signs of upstream inflow and infiltration, respectively, realted to the rain event Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 9/5/13 9/7/13 9/9/13 9/11/13 9/13/13 Date

46 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wilson Avenue 18" (Flow Monitor.2) Flow rate and level data generally appear to ride together. Level data is highly reliably while flow rate data is reliable with the exception of time from to During this time period the flow meter did not accurately record velocity data and couldn't calculate the flow rate accurately Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 9/13/13 9/23/13 1/3/13 1/13/13 1/23/13 11/2/13 11/12/13 Date

47 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wilson Avenue 18" (Flow Monitor.2) Approximately 5" or rain was received on 9/9/13. This rain event resulted in increased flow in the Wilson Avenue 18" trunk sewer. Even during this large rain event the trunk sewer did not become surcharged, reaching a maximum level of ~9.5". The trunk sewer never became surcharged during flow monitoring. It is important to note the sharp spikes in both flow rate and level followed by a maintained increase in both flow rate and level for two days after the rain event. These are signs of upstream inflow and infiltration, respectively, realted to the rain event Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 9/5/13 9/7/13 9/9/13 9/11/13 9/13/13 Date

48 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wilson Avenue 15" (Flow Monitor.3) Flow Rate (cfs) Level (inches) Rainfall (in/hr) 9/5/13 9/15/13 9/25/13 1/5/13 1/15/13 1/25/13 11/4/13 11/14/13 Date

49 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wilson Avenue 15" (Flow Monitor.3) The sharp spikes in flow rate without a similar increase in level may indicate high flow from the 4th Street Lift Station Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 1/2/13 1/4/13 1/6/13 1/8/13 1/1/13 Date

50 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Ivanrest Avenue 16" (Flow Monitor.4) Flow rate and level data appear to ride together. Both measures are reliable Flow Rate (cfs) Rainfall (in/hr) Level (in) /4/13 9/14/13 9/24/13 1/4/13 1/14/13 1/24/13 11/3/13 11/13/13 Date

51 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Ivanrest Avenue 16" (Flow Monitor.4) Small rain events result in sharp increases in flow entering Study Area 3 from the trunk sewer adjacent to Buck Creek to the East of Ivanrest. This is indicative of inflow Flow Rate (cfs) Rainfall (in/hr) Level (in) /29/13 1/31/13 11/2/13 11/4/13 11/6/13 11/8/13 11/1/13 11/12/13 Date

52 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Ivanrest Avenue 12" (Flow Monitor.5) Flow rate and level data generally appear to ride together. Both measures are reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /11/13 1/16/13 1/21/13 1/26/13 1/31/13 11/5/13 11/1/13 11/15/13 11/2/13 Date

53 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Ivanrest Avenue 12" (Flow Monitor.5) A slight increase in flow was observed during small rain events. An more substantial increase in flow was observed during the larger rain event on 11/17/13. This flow pattern is more indicative of infiltration, but could also be related to inflow Flow Rate (cfs) Level (inches) Rainfall (in/hr) /12/13 11/13/13 11/14/13 11/15/13 11/16/13 11/17/13 11/18/13 11/19/13 11/2/13 Date

54 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Mohave Court 8" (Flow Monitor 1.1) Flow rate and level data appear to ride together. Both measures are reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /29/13 9/8/13 9/18/13 9/28/13 1/8/13 1/18/13 1/28/13 11/7/13 11/17/13 Date

55 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Mohave Court 8" (Flow Monitor 1.1) During dry weather, the level in the sewer remained around 4" deep and the flow rate never substantially decreased. This is indicative of infiltration. During larger rain events large spikes in flow were recorded. This is indicative of inflow. These flow conditions are partially the result of upstream conditions (Choctaw Drive & Aaron Avenue areas) Flow Rate (cfs) Level (inches) Rainfall (in/hr) /5/13 9/6/13 9/7/13 9/8/13 9/9/13 9/1/13 9/11/13 9/12/13 9/13/13 Date

56 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Choctaw Drive 8" (Flow Monitor 1.2) Level data is reliable. Flow data was not recorded for a majority of the monitoring duration and was not reliable when it did record Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/13 9/9/13 9/19/13 9/29/13 1/9/13 1/19/13 1/29/13 11/8/13 11/18/13 Date

57 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Choctaw Drive 8" (Flow Monitor 1.2) During dry weather, the level in the sewer remained around 5" deep. This is indicative of infiltration. Large spikes in flow were recorded during rain events. This is indicative of inflow. The level remains elevated days after rain events. This is a sign of infiltration Flow Rate (cfs) Level (inches) Rainfall (in/hr) /5/13 9/6/13 9/7/13 9/8/13 9/9/13 9/1/13 9/11/13 9/12/13 9/13/13 Date

58 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Aaron Avenue 8" (Flow Monitor 1.3) No strong correlation between level and flow rate. Flow rate data is sporadic and not reliable. Level data follows a diurnal pattern and is reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /28/13 9/7/13 9/17/13 9/27/13 1/7/13 1/17/13 1/27/13 11/6/13 11/16/13 Date

59 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) As witht the other sub-areas in Study Area 1, the level in the sewer remained elevated at all times indicating significant infiltration. Level spiked during rain events, which indicates inflow. Unlike the other sub-areas in the Study Area, the level quickly returned to the pre-rain level. Aaron Avenue 8" (Flow Monitor 1.3) Flow Rate (cfs) Level (inches) Rainfall (in/hr) /5/13 9/6/13 9/7/13 9/8/13 9/9/13 9/1/13 9/11/13 9/12/13 9/13/13 Date

60 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) North Big Springs Drive 1" (Flow Monitor 2.1) Flow rate and level data appear to ride together. Both measures are reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr).2.5 1/18/13 1/23/13 1/28/13 11/2/13 11/7/13 11/12/13 11/17/13 Date

61 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) North Big Springs Drive 1" (Flow Monitor 2.1) The sewer flow follows a typical diurnal pattern during dry weather. During a large rain event, the flow increases slightly without any sharp spikes. This is indicative of infiltration, which can be partially attributed to upstream (primarily Yellowstone Drive) conditions Flow Rate (cfs) Level (inches) Rainfall (in/hr) /14/13 11/15/13 11/16/13 11/17/13 11/18/13 11/19/13 11/2/13 Date

62 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Iris Drive 8" (Flow Monitor 2.2).3.25 Flow rate and level data appear to ride together. Both measures are reliable Flow Rate (cfs) Level (in) Rainfall (in/hr).5.5 1/14/13 1/19/13 1/24/13 1/29/13 11/3/13 11/8/13 11/13/13 11/18/13 Date

63 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Iris Drive 8" (Flow Monitor 2.2) Rain events do not cause any measurable inflow or infiltration in this location. Base flows are minimal and show no signs of dry weather infiltration Flow Rate (cfs) Level (in) Rainfall (in/hr) /14/13 11/15/13 11/16/13 11/17/13 11/18/13 11/19/13 11/2/13 Date

64 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Yellowstone Drive 8" (Flow Monitor 2.3) Flow rate and level data generally appear to ride together. Both measures are reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /14/13 1/19/13 1/24/13 1/29/13 11/3/13 11/8/13 11/13/13 11/18/13 Date

65 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Yellowstone Drive 8" (Flow Monitor 2.3) The sewer flow follows a typical diurnal pattern during dry weather. During a large rain event, the flow increases slightly without any sharp spikes. This is indicative of infiltration Flow Rate (cfs) Level (inches) Rainfall (in/hr) /14/13 11/15/13 11/16/13 11/17/13 11/18/13 11/19/13 11/2/13 Date

66 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wayburn Avenue 8" (Flow Monitor 3.1) Flow Rate (cfs) Level (inches) Rainfall (in/hr) /11/2131/16/2131/21/2131/26/2131/31/21311/5/21311/1/21311/15/21311/2/213 Date

67 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Wayburn Avenue 8" (Flow Monitor 3.1) The sewer flow follows a typical diurnal pattern during dry weather. During rain events, the flow increases dramatically and remains elevated for ~24 hours after the rain event. This indicates that there is both inflow and infiltration in this area Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/2131/31/21311/1/21311/2/21311/3/21311/4/21311/5/21311/6/21311/7/21311/8/213 Date

68 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Woodbine Avenue 12" (Flow Monitor 3.2).12.1 Flow rate and level data generally appear to ride together. Both measures are reliable Flow Rate (cfs) Level (inches) Rainfall (in/hr) /11/2131/16/2131/21/2131/26/2131/31/213 11/5/213 11/1/21311/15/21311/2/213 Date

69 Flow Rate (cfs) Depth (inches) Rainfall Intensity (in/hr) Woodbine Avenue 12" (Flow Monitor 3.2).12.1 During rain events, there are occasional short term spikes in flow that seem to indicate inflow, possibly in the form of a sump pump connected to the sanitary sewer Flow Rate (cfs) Level (inches) Rainfall (in/hr) /3/2131/31/21311/1/21311/2/21311/3/21311/4/21311/5/21311/6/21311/7/21311/8/213 Date