William Street Pond Iron-Enhanced Sand Filter Performance Report

Transcription

1 William Street Pond Iron-Enhanced Sand Filter Performance Report May 2017 PREPARED BY: Capitol Region Watershed District DATE: 05/04/2017 CAPITOL REGION WATERSHED DISTRICT 2017

2 Table of Contents Acronyms and Abbreviations... i Definitions... ii List of Figures... iii List of Tables... iii Introduction... 1 Background... 1 IESF as a Method of Phosphorus Reduction... 3 IESF at William Street Pond... 3 Methods... 5 Results... 6 Total Phosphorus... 8 Statistical Results Orthophosphate Statistical Results Conclusions References Appendix A: Parameter Result Tables Appendix B: Individual Filter Removal Efficiency Appendix B: William Street Pond IESF As-Built... 22

3 Acronyms and Abbreviations BMP CRWD H0 Ha IESF L MCES MDL MPCA mg Ortho-P QAPP SAFL TMDL TP WSP Best Management Practice Capitol Region Watershed District Null Hypothesis Alternative Hypothesis Iron-Enhanced Sand Filter Liter Metropolitan Council Environmental Services Method Detection Limit Minnesota Pollution Control Agency Milligram Orthophosphate Quality Assurance Program Plan St. Anthony Falls Laboratory Total Maximum Daily Load Total Phosphorus William Street Pond William Street Pond IESF Performance Report i

4 Definitions Best Management Practice technique, measure, or structural control that is used for a given set of conditions to manage the quantity and improve the quality of stormwater runoff in the most cost effective manner. Grab sample a water sample that is obtained by taking a single sample. Impaired Waters waters that are not meeting their designated uses because of excess pollutants violating water quality standards. Method Detection Limit the minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero Orthophosphate (PO4 3- ) soluble, inorganic form of phosphorus that can be directly taken up by plants and algae Removal Efficiency a percent that represents the value removed relative to the value that entered the system Stormwater water that becomes runoff on a landscape during a precipitation event. Subwatershed a delineated area of land within a larger watershed where surface waters and runoff drain to a single point before ultimately discharging from the encompassing watershed. Total Maximum Daily Load the maximum amount of a substance that can be received by a water body while still meeting water quality standards. This may also refer to the allocation of acceptable portions of this load to different sources. Total Phosphorus measure of all forms of phosphorus, including dissolved and particulate; often the limiting nutrient for algal growth in oligo- and mesotrophic waters and thus the focus of many nutrient control programs Watershed a delineated area of land where surface waters and runoff drain to a single point at a lower elevation. William Street Pond IESF Performance Report ii

5 List of Tables Table 1: Five number summary of TP results, Table 2: Five number summary of ortho-p results, List of Figures Figure 1: William Street Pond location within Lake McCarrons subwatershed... 2 Figure 2: Phosphorus Species... 2 Figure 3: Iron-enhanced sand filter illustrations, North (top) and South (bottom)... 4 Figure 4: Monitoring Locations: Pond, North Filter, South Filter Figure 5: William Street Pond Level, Overflow Weir Elevation, and Daily University of Minnesota Climatological Observational Rain Gauge Figure 6: Average annual removal efficiencies from influent to effluent for TP and ortho-p... 8 Figure 7: TP concentrations of influent and effluent shown with event rainfall, Figure 8: Average TP concentrations of influent and effluent by month, Figure 9: TP influent and effluent concentration boxplots, Figure 10: Ortho-P concentrations of influent and effluent shown with event rainfall, Figure 11: Average ortho-p concentrations of influent and effluent by month, Figure 12: Ortho-P influent and effluent concentration boxplots, William Street Pond IESF Performance Report iii

6 Introduction William Street Pond is a stormwater detention and sedimentation basin located in Roseville, MN. Originally converted from a wetland in 1990, the pond receives stormwater from the surrounding urbanized residential neighborhood and discharges directly to Lake McCarrons, a 75-acre deep lake that supports a variety of recreational opportunities. Several projects have been implemented over the last 15 years in Lake McCarrons and its watershed to reduce the phosphorus load to the lake. In 2011, significant improvements were made at William Street Pond to improve the quality of the water being discharged to Lake McCarrons. These improvements included: 1. The installation of a SAFL Baffle at the pond inlet to dissipate the flow energy of the water entering the pond, remove suspended solids, and trap large debris. 2. The dredging of sediment from the pond to restore its original storage capacity and improve the pond s ability to settle suspended solids. 3. An outlet retrofit to include two iron-enhanced sand filters (IESF) that drain into an outlet structure with a weir overflow, which then flows to Lake McCarrons. The goal of the IESF project at William Street Pond (WSP) is to prevent the excessive growth of algae and macrophytes in Lake McCarrons by binding phosphorus from the pond that would otherwise be discharged to the lake. Within the Lake McCarrons subwatershed, WSP accounts for the second highest phosphorus input, after the Villa Park Wetland system (Figure 1). Background Phosphorus is an essential element to aquatic ecosystems. Total phosphorus (TP) is a measurement of both dissolved and particulate phosphorus (Figure 2). Total dissolved phosphorus represents all soluble phosphorus compounds, organic or inorganic; including orthophosphate. Orthophosphate (ortho-p) is the soluble, inorganic form of phosphorus that can be directly taken up by plants and algae. Excess phosphorus concentrations can cause eutrophication in freshwater lakes, which creates prime conditions for algal blooms and fish kills (Carpenter et al., 1998). Urban stormwater runoff is identified as a primary nonpoint source that contributes to increased phosphorus concentrations in urban lakes. The Minnesota Pollution Control Agency (MCPA) Impaired Waters List identifies bodies of water that fail to meet water quality standards (MPCA, 2017). Once a water body is added to this list, the MPCA conducts a Total Maximum Daily Load (TMDL) study to determine the sources of a pollutant and the maximum amount of a pollutant it can receive in order to meet water quality standards. William Street Pond IESF Performance Report 1

7 Figure 1: William Street Pond location within Lake McCarrons subwatershed. Orthophosphate Total Dissolved Phosphorus Polyphosphates Total Phosphorus Other Dissolved Phosphorous Organic Phosphorus Compounds Other Particulate Phosphorus Figure 2: Phosphorus Species. William Street Pond IESF Performance Report 2

8 Phosphorus is one of the primary concerns in Lake McCarrons and the surrounding watershed. Currently, Lake McCarrons is not listed on the MPCA Impaired Waters List. The 2003 Lake McCarrons Management Plan (CRWD, 2003) identified a target TP concentration of mg/l 1 to minimize the risk of algal blooms. CRWD completed an aluminum sulfate treatment on Lake McCarrons in 2004 to help bind soluble phosphorus particles and reduce the amount of available phosphorus in the lake. To decrease external sediment and nutrient loading to the lake, improvements projects in 2004 and 2013 targeted the Villa Park Wetland System, a series of constructed wetland cells that treats 70% of the lake s inputs (CRWD, 2010). IESF as a Method of Phosphorus Reduction To reduce the risks associated with elevated phosphorus concentrations, best management practices (BMPs) must focus on capturing not only particulate but also dissolved phosphorus species, like ortho-p (Erickson et al., 2012). Sand filtration is a common feature in BMPs to remove particulate matter in stormwater. Iron-enhanced sand filters include large beds of sand mixed with iron filings, the addition of which significantly increases the filter s capacity to remove dissolved phosphorous. When water contacts an IESF, the oxidized iron filings remove a significant portion of phosphorus through surface sorption. The Minnesota IESF (Erickson et al., 2012) was developed at the University of Minnesota St. Anthony Falls Laboratory by Gulliver, Erickson, and Weiss in An initial 2007 study indicated a 51-81% reduction in dissolved phosphorus in synthetic stormwater passed through columns of sand media enhanced with 2% granular steel wool, by weight (Weiss et al., 2007). A similar 2012 column study indicated, on average, an 88% reduction in dissolved phosphorus in synthetic stormwater passed through a sand media mixed with 5% iron filings, and 79% with 2% iron filings (Erickson et al., 2012). The Minnesota IESF has been applied to many stormwater BMP projects throughout the Twin Cities metropolitan area. Data collected in the years following the installation of filters in the cities of Prior Lake, Stillwater, and Maplewood, MN showed reductions of total phosphorus of 45% 2, 82%, and 75%, respectively (Erickson et al., 2015; Kill & Fleming, 2016; Erickson, 2012). IESF at William Street Pond WSP features two IESF s along the slopes of the pond near the pond outlet structure. Cross-sections of the North and South IESFs at WSP are shown in Figure 3. Both filters feature a layer of coarse filter aggregate underneath sand and iron-enhanced sand layers composed of 5% iron filings. The filters 1 The Minnesota deep lake standard for TP is mg/l. 2 Percent phosphorus reduction of the Prior Lake IESF from was 26%; after non-routine maintenance in 2014, percent reduction of phosphorus increased to 45% for remainder of William Street Pond IESF Performance Report 3

9 differ by the type of material separating the filter media from the pond interface. The north filter features a barrier of crushed limestone cobble while the south filter features a 16 diameter Pyramat roll. When the pond level fluctuates during a storm event to an elevation greater than ft., water flows onto and through the pond banks and drains down through the iron-enhanced sand layer. Water flows to the underlying drain tiles within the filters, then to the outlet structure. A weir is in place in the outlet to allow water to bypass the filter beds under higher stormflow conditions to prevent flooding. Both the weir and the two drain tiles empty into a sump before leaving the outlet structure and flowing to Lake McCarrons. Figure 3: Iron-enhanced sand filter illustrations, South (top) and North (bottom). William Street Pond IESF Performance Report 4

10 Methods CRWD staff designed and implemented a monitoring plan to assess the efficacy of the iron-enhanced sand filters for phosphorus removal. Grab samples were collected from 2013 to 2016 in sets of three: one influent sample (WSP Pond) and two effluent locations (WSP North Filter, WSP South Filter) (Figure 4). Each sampling set was collected at the same time within 24 hours of storm events greater than 0.5 inches. Pond Monitoring Location North and South Filter Monitoring Location Figure 4: Monitoring Locations: Pond, North Filter, South Filter. William Street Pond IESF Performance Report 5

11 Metropolitan Council Environmental Services (MCES) performed the chemical analysis for all samples. The samples were analyzed for a suite of characteristics, with TP and ortho-p being most pertinent to this study. MCES method detection limits (MDL) were 0.02 mg/l for TP and mg/l for ortho-p. Several ortho-p concentrations were reported as below the MDL. A value equaling half the detection limit was substituted for these concentrations (Erickson, 2012). Rainfall data were collected using the University of Minnesota St. Paul Climatological Observatory 15- minute rainfall dataset. Water level in WSP was recorded by CRWD using a Global Water pressure transducer level logger. Level observances were recorded every ten minutes from approximately April through November. Effluent water quality data were analyzed as an average of WSP North Filter and WSP South Filter, unless otherwise noted. Removal efficiencies were calculated for all samples collected, as shown in Equation 1: rrrrrrrrrrrrrr eeeeeeeeeeeeeeeeeeee (%) = iiiiiiiiiiiiiiii cccccccc. mmmm eeeeeeeeeeeeeeee cccccccc. mmmm LL LL 100% (Eq. 1) iiiiiiiiiiiiiiii cccccccc. mmmm LL A one-sided Wilcoxon Rank Sum test was used in order to determine whether a conclusion was significant. This test evaluates two independent groups to determine whether one group tends to produce larger values than the second (Helsel & Hirsch, 2002). This test is non-parametric, and therefore appropriate for this study as the data do not follow a normal distribution. The tests were run with R software using a confidence interval of 95%. The resultant p-values were evaluated to be significant at values less than or equal to an alpha value of Results The TP and ortho-p results, sample dates, and associated rainfalls for samples collected from are listed in Appendix A. A total of 29 sampling events occurred during the surveying period. University of Minnesota daily precipitation and pond level response is shown in Figure 5. The median TP and ortho-p reductions are 67.5% and 73.5%, respectively (Figure 6). William Street Pond IESF Performance Report 6

12 Figure 5: William Street Pond Level, Overflow Weir Elevation, and Daily University of Minnesota Climatological Observational Rain Gauge. William Street Pond IESF Performance Report 7

13 90% 80% 70% 60% 84.2% 81.2% 79.7% 67.5% 72.1% 62.7% 50% 40% 55.7% 50.0% 30% 20% 10% 0% TP ortho-p Figure 6: Average annual removal efficiencies from influent to effluent for TP and ortho-p. Ninety-seven percent of samples taken during the sample period showed a reduction of TP (Figure 7). Similar reductions were observed for ortho-p, with 48% of the effluent samples being analyzed under the MDL (Figure A-2). Further, effluent samples from the filters showed very consistent TP and ortho-p concentrations, with no apparent correlation to the amount of rainfall or the influent concentration (Figures 8 & 10). Specific results for TP and ortho-p are described in the following subsections. Total Phosphorus TP results and removal efficiencies for the sampling period are presented in Table A-1 in Appendix A. TP concentration results and corresponding event precipitation records are shown in Figure 7. Influent TP fluctuated throughout the years. Despite influent fluctuations, effluent concentrations largely remained the same. Only one sample (8/7/2013) measured a TP effluent higher than the influent concentration. This can be considered insignificant, as the influent concentration was very low, and the resulting effluent was within the normal range of values. Neither influent nor effluent is significantly correlated to precipitation. No influent or effluent samples returned concentration values less than the MDL of 0.02 mg/l. Monthly average TP concentrations are shown in Figure 8. Influent TP concentrations are highest in the months of June and October, and lowest in early spring, August, and late fall. Effluent TP concentrations do not follow a similar pattern, and peak slightly in August and September. William Street Pond IESF Performance Report 8

14 TP Rainfall (in) /10 7/15 8/5 8/7 8/30 10/3 10/16 4/30 5/20 6/17 6/20 9/5 9/10 9/22 10/2 5/27 6/23 7/13 7/28 8/19 9/18 11/19 5/11 6/9 6/15 7/6 8/12 10/5 10/ Rainfall Influent Effluent 12.0 Figure 7: TP concentrations of influent and effluent shown with event rainfall, TP Apr May Jun Jul Aug Sep Oct Nov Average TP Influent Average TP Effluent Figure 8: Average TP concentrations of influent and effluent by month, William Street Pond IESF Performance Report 9

15 A five number summary of TP sample results are shown in Table 1. These values are reflected in the TP boxplots shown in Figure 9. For TP, the median of influent samples was over 300% greater than median average effluent. The mean average effluent from both the north and south filters is six and a half standard deviations away from the mean influent value. Further, the 100 th percentile of the effluent samples does not cross the 25 th percentile of the influent samples. Both influent and effluent averages are greater than the medians, suggesting that both data sets are right skewed. There were no significant differences in performance between the two filters (alpha = 0.05). Table 1: Five number summary of TP results, *Effluent concentration represents average of north and south filter. See Appendix B for individual filter removal efficiency Influent TP Conc. Effluent Conc. Removal Efficiency (%) Average Median Min Max St.Dev Figure 9: TP influent and effluent concentration boxplots, William Street Pond IESF Performance Report 10

16 Statistical Results A one-sided Wilcoxon Rank Sum test was conducted to determine whether the decrease in TP from the influent samples to the effluent sample are statistically significant. The test was run with an alpha value of The test hypotheses were constructed as follows: H0 Influent and effluent TP populations are similar, no improvement on water quality is made. Ha Influent TP is higher than effluent TP, improvement observed The resultant p-value for the difference in influent and effluent TP was 2.732E-10. As the p-value < alpha value, the null hypothesis was rejected in favor of the alternative hypothesis. Thus, there exists significant statistical evidence that the influent TP is higher than the effluent TP; therefore, the filters are effective at removing TP. Orthophosphate Ortho-P results for sample period are presented in Table A-2 in Appendix A. Ortho-P concentration results and corresponding event precipitation records are shown in Figure 10. Four of twenty-seven influent samples (14%) were measured at or below the MDL for ortho-p (0.005 mg/l). Twenty-seven of the 56 north and south filter effluent samples results (48%) were measured at or below the MDL. Two samples resulted in ortho-p concentrations at or under the MDL for all three event samples. Both occasions occurred during the month of October. There is no significant correlation between precipitation and influent or effluent samples. Numerous spikes can be observed in the influent sample concentrations throughout the sampling period (Figure 10). Effluent samples remain at a low, consistent level throughout the sampling period, slightly responding to influent spikes. Only two sampling sets produced higher ortho-p effluent concentrations than influent concentrations (5/20/2014 & 7/28/2015). On these occasions, the influent concentrations were measured to be at or under the MDL, and the effluent concentrations were consistent with other results observed throughout the sampling period. Average monthly ortho-p concentrations are shown in Figure 11. Influent and effluent ortho-p average concentrations follow similar trends. Both influent and effluent samples exhibit the highest average ortho-p concentrations during the months of May and June. Ortho-p concentrations dip during the fall months. This is expected, as ortho-p measures soluble and reactive types of phosphorus. This subset of phosphorus is most available in wetlands and ponds in the spring in early summer when primary productivity is highest. William Street Pond IESF Performance Report 11

17 ortho-p Rainfall (in) /10 7/15 8/5 8/7 8/30 10/3 10/16 4/30 5/20 6/17 6/20 9/5 9/10 9/22 10/2 5/27 6/23 7/13 7/28 8/19 9/18 11/19 5/11 6/9 6/15 7/6 8/12 10/5 10/ Rainfall Influent Effluent 12.0 Figure 10: Ortho-P concentrations of influent and effluent shown with event rainfall, ortho-p Apr May Jun Jul Aug Sep Oct Nov Average ortho-p Influent Average ortho-p Effluent Figure 11: Average ortho-p concentrations of influent and effluent by month, William Street Pond IESF Performance Report 12

18 A five number summary of ortho-p sample results is shown in Table 2. These values are visualized in the ortho-p boxplots in Figure 12. The median influent concentration is 4.2 times greater than the median average effluent concentration. The mean influent concentration is 3.6 standard deviations higher than the mean average effluent concentration. The mean values for influent and effluent concentrations are higher than the corresponding median values, suggesting that the data are right skewed. Table 2: Five number summary of ortho-p results, *Effluent concentration represents the average of north and south filter. See Appendix B for individual filter removal efficiency Influent ortho-p Conc. Effluent Conc. Removal Efficiency (%) Average Median Min Max St.Dev Figure 12: Ortho-P influent and effluent concentration boxplots, William Street Pond IESF Performance Report 13

19 Statistical Results A one-sided Wilcoxon Rank Sum test was conducted to determine whether the decrease in ortho-p from the influent samples to the effluent sample are statistically significant. The test was run with an alpha value of The test hypotheses were constructed as follows: H0 Influent and effluent ortho-p populations are similar, no improvement on water quality is made. Ha Influent ortho-p is higher than effluent ortho-p, improvement observed The resultant p-value for the difference in influent and effluent total phosphorus was 3.23 E-03. As the p-value < alpha value, the null hypothesis was rejected in favor of the alternative hypothesis. Thus, there exists significant statistical evidence that the influent ortho-p is higher than the effluent ortho-p; therefore, the filters are effectively treating stormwater for ortho-p. Conclusions The iron-enhanced sand filters installed at the William St. Pond are successfully reducing the amount of phosphorus entering Lake McCarrons. Assessing their effectiveness with a simple removal efficiency statistic would indicate a four-year median of 67.5% TP and 73.8% ortho-p removed. The 67.5% TP removal efficiency is within the range of cited removal statistics for other IESF implementations in the Twin Cities area. For all years, the IESF benches produced consistent, low-phosphorus effluent. Further, the majority of effluent ortho-p results were measured at or below the MDL. Influent sample concentrations for both TP and ortho-p both exhibited spikes throughout the respective sampling periods; however, the dates of ortho-p influent spikes do not match the dates of the TP influent spikes. This suggests that factors contributing to TP and ortho-p cycling in the pond have differing seasonality. Ortho-P spikes generally occurred in early summer when primary productivity in ponds are highest. TP spikes occur later in summer and early fall. Since TP is a measure of both particulate and dissolved phosphorus, the later summer spikes accurately indicate plant senescence and phytoplankton breakdown. Effluent concentrations exhibit no correlation with influent concentrations or rainfall totals. This suggests that the contact time with the iron is sufficient to achieve near maximum reductions in phosphorus concentrations. It suggests that the IESFs have not yet shown signs of reaching their maximum phosphorus adsorption capacity or lifespan. It also may suggest that the benches are able to accommodate a higher phosphorus loading than what has been evaluated in the events included in this analysis. The ortho-p results are slightly less conclusive than the TP results, as indicated by a slightly larger Wilcoxon Rank Sum p-value. Nearly 50% of ortho-p effluent values were reported at or under the MDL. William Street Pond IESF Performance Report 14

20 The observed decrease in the ortho-p set from the effluent as compared to influent may have been greater if these values were known, instead of being reported as <0.05. Continued monitoring at William Street Pond will assure the continued performance of the IESFs. Additionally, it may help develop an estimate of the length of time that the benches will remain effective before needing replacement or maintenance, as their capacity to precipitate phosphorus will gradually become exhausted. William Street Pond IESF Performance Report 15

21 References Capitol Region Watershed District (CRWD), Lake McCarrons Management Plan. Saint Paul, MN. Capitol Region Watershed District (CRWD), Villa Park Wetland System Management Plan. Saint Paul, MN. Carpenter, Stephen R., et al. "Nonpoint pollution of surface waters with phosphorus and nitrogen." Ecological applications 8.3 (1998): Erickson, Andrew J., John S. Gulliver, and Peter T. Weiss. "Capturing phosphates with iron enhanced sand filtration." Water research 46.9 (2012): Erickson, Andrew J., John S. Gulliver, and Peter T. Weiss. "Monitoring an Iron-Enhanced Sand Filter Trench for the Capture of Phosphate from Stormwater Runoff." (2015). Erickson, Andrew J. Removing Dissolved Pollutants from Stormwater Runoff. St. Anthony Falls Labortory, University of Minnesota. Presentation October 3, (2012) Helsel, D.R. & Hirsch, R. M. Statistical Methods in Water Resources. Vol. 49. Elsevier, Kill, Karen & Fleming, Ryan. Pump and Treat Iron Enhanced Stormwater Treatment. Brown s Creek watershed District & EOR, Minnesota Water Resources Conference, 18 October St. Paul, MN. Conference Presentation Minnesota Pollution Control Agency (MPCA), Total Maximum Daily Load (TMDL) projects. Accessed online from Weiss, Peter T., John S. Gulliver, and Andrew J. Erickson. "Cost and pollutant removal of storm-water treatment practices." Journal of Water Resources Planning and Management (2007): William Street Pond IESF Performance Report 16

22 APPENDIX A. Parameter Results Tables William Street Pond IESF Performance Report 17

23 Table A-1: William Street Pond TP results. Rainfall (in.) Sampling Date Influent TP Conc. N. Filter Effluent Conc. S. Filter Effluent Conc. Avg. Effluent Conc. N. Filter Removal Efficiency (%) S. Filter Removal Efficiency (%) Avg. Removal Efficiency (%) /10/ /15/ /5/ /7/ /30/ /3/ /16/ /30/ /20/ /17/ /20/ /5/ /10/ /22/ /2/ /27/ /23/ /13/ /28/ /19/ /18/ /19/ /11/ /9/ /15/ /6/ /12/ /5/ /27/ William Street Pond IESF Performance Report 18

24 Table A-2: William Street Pond orthophosphate results. Rainfall (in.) Sampling Date Influent ortho-p Conc. N. Filter Effluent Conc. S. Filter Effluent Conc. Avg. Effluent Conc. N. Filter Removal Efficiency (%) S. Filter Removal Efficiency (%) Avg. Removal Efficiency (%) /10/ /15/ /05/ /07/ /30/ /03/ /16/ /30/ /20/ /17/ /5/ /10/ /22/ /2/ /27/ /23/ /13/ /28/ /19/ /18/ /19/ /11/ /9/ /15/ /6/ /12/ /5/ /25/ Datum at or below detection limit, represented as half detection limit ( mg/l) William Street Pond IESF Performance Report 19

25 APPENDIX B. Individual Filter Removal Efficiency William Street Pond IESF Performance Report 20

26 Table B-1: North and South Filter Removal Efficiency: TP Influent TP Conc. N. Filter Effluent Conc. S. Filter Effluent Conc. N. Filter Removal Efficiency (%) S. Filter Removal Efficiency (%) Average Median Min Max St.Dev Table B-2: North and South Filter Removal Efficiency: ortho-p Influent ortho-p Conc. N. Filter Effluent Conc. S. Filter Effluent Conc. N. Filter Removal Efficiency (%) S. Filter Removal Efficiency (%) Average Median Min Max St.Dev William Street Pond IESF Performance Report 21

27 APPENDIX C. William Street Pond IESF As-Built William Street Pond IESF Performance Report 22

28 William Street Pond IESF Performance Report 23