Portland State University PDXScholar Dissertations and Theses Dissertations and Theses Winter 4-18-2013 Statistical Analysis of Stormwater Device Testing Protocols in Portland, Oregon Zahra Kavianpour Isfahani Portland State University Follow this and additional works at: https://pdxscholar.edu/open_access_etds Part of the Water Resource Management Commons Let us know how access to this document benefits you. Recommended Citation Kavianpour Isfahani, Zahra, "Statistical Analysis of Stormwater Device Testing Protocols in Portland, Oregon" (2013). Dissertations and Theses.676 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar.
Please contact us if we can make this document more accessible: pdxscholar@pdx. Statistical Analysis of Stormwater Device Testing Protocols in Portland, Oregon by Zahra Kavianpour Isfahani A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Civil and Environmental Engineering Thesis Committee: William Fish, Chair Scott Wells Hamid Moradkhani Portland State University 2013 Abstract Stormwater treatment is commonly performed with a combination of approaches including the utilization of natural systems and engineered devices. Before using a proprietary treatment instrument it is required to verify its performance and efficiency in reducing different pollution components including the TSS. Different states have developed strategies and regulations for accepting new instruments.
In this thesis the stormwater management plan of the City of Portland, Oregon (2008), is analyzed in order to improve the current regulations. These rules apply to new technologies which are proposed by vendors to be used in Portland’s stormwater treatment plans. Each requirement which should be met by the applying vendors is thoroughly analyzed followed by a comparison with the Stormwater management plan(2008)regulations of the state of Washington the so called Technology Assessment Plan-Ecology TAPE (Howie, 2011). Because of the similarities in the climate and land use between these two testing frameworks in order to evaluate the potential applicability of data submitted by vendors who had devices approved by Washington, to be utilized by Portland.
The treatment of total suspended solids (TSS) is the focus of this thesis since it is central to the testing process and since most of the other pollutions are attached to TSS and will get treated if TSS is treated. The overall analysis shows that Portland adopts more restrictive requirements on the characterization of stormwater event samples to be treated by a technological instrument while Washington’s restriction are more stringent on the efficiency of total suspended solid removal, in which it demands i higher standards on the treatment of TSS compared to Portland’s efficiency requirements. In order to study practical context in which regulations are administrated by Portland, rainfall data from 66 gauges covering the period of 1980-2011 was studied and the impacts of seasonality, land use, land form, periods of no rain before and after an event and Portland’s Modified Performance line on the number of accepted rain events were analyzed. The results which were accepted by state of Washington were also compared with the results accepted by the city of Portland on Portland’s Standard Performance line.
Our seasonality study suggests that Portland’s requirements are unnecessarily restrictive which results in the disqualification of many otherwise useful stormwater events, sometimes allowing no natural events to be available for testing in dry years. The analysis of land use showed that land use has no statistically significant impact on the concentration levels of TSS, thereby indicating that land use restrictions in the testing rules could be usefully relaxed. Decreasing the interevent no-rain period significantly increases the total number of events providing sufficient data to assess the performance of treatment facilities. We also showed that many more events become suitable for performance testing if events separated by one hours or less are considered a single, longer event.
Finally we identified a statistical relationship between number of forecasted accepted stormwater events and the total average daily precipitation in a given year. ii In The Name of God, The Most Compassionate and Merciful I dedicate this thesis to my husband and my best friend, Reza, who has always been by my side, with unconditional love, help and support, encouraging me to follow what I am passionate about. To my daughter, Ava, whose presence makes me the happiest person and the proudest mother. And to my parents and little sister, Sarah, who have always been my role models and helped me start my journey and showered me with their love and support throughout the way.
iii Acknowledgments I would like to acknowledge with my greatest thanks to my advisor, Professor William Fish for all his guidance throughout my thesis; and for introducing me to the subject which provided a new path in my studies. I would also like to thank him for his inspirational classes which introduced me to a new perspective, and from those classes I found what I was truly passionate about. I would like to thank Mr. Guy Alvis for being available any time I had a question or needed more information.
The data which are used in this study are through the efforts of Mr. I thank my thesis committee members Professor Scott Wells and Professor Hamid Moradkhani. They were great help for starting my new major and kindly advised me on my path. They helped me understand my abilities and interests and guided me from my very first steps in Portland State University, and for that I am deeply thankful.
My gratitude is to the Department of Civil and Engineering’s staff, especially Megan Niermeyer who have always been available to help and answer questions. I deeply thank all my family members and friends, whose support has been a reason for my confidence and efforts. The funding for this research study was provided by the City of Portland, Bureau of Environmental Services. iv Contents Abstract.
ix Chapter 1: Introduction. 1 Chapter 2: Stormwater Pollutants. 6 Sources of Pollutants. 10 Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).
11 Toxic Organic Waste. 11 Pathogenic Micro-Organisms. 12 Chapter 3: Regulation Policies. 14 The Clean Water Act.
14 Stormwater Treatment Technologies. 17 Chapter 4: Portland Stormwater Management System. 18 Stormwater Treatment in Portland. 18 Stormwater Management Requirements of the City of Portland.
20 Total Suspended Solids. 21 TMDL Enhanced Performance Goal. 22 v Oil and Grease Removal. 23 Technology Assessment Protocol- Ecology (TAPE).
24 Comparing the City of Portland’s Stormwater Management System and TAPE. 24 Challenges in the Current Stormwater Treatment Policies of Portland. 34 Statistical Analysis of Portland Rainfall Events for Sampling Suitability. 34 Estimating the Number of Events Using the Average Daily Precipitation.
42 Comparing the effects of rainfall depth, intensity and duration on removal TSS efficiency. 59 Six Hourly Duration of No Rain Before and After a Rainfall Event. 63 Connecting Events with 1 Hour Interevent Periods. 69 Portland’s Modified Performance Standard Line.
73 Part I of trisected Portland’s Modified Performance standard Line. 78 Part II of Portland’s Modified Performance standard Line. 80 Part III of Portland’s Modified Performance Standard Line. 82 Differences between Land Covers.
91 Appendix – more additional information. 93 Sample Data Collection Sheet. 94 Portland Gauge Information. 96 Current Approved List of Vendors by City of Portland as of April 2005.
99 Summary of Best Management Practices by City of Portland. 100 vi Tables Table 1- Sources of urban pollutants at individual sites – (Minton, 2002). 7 Table 2: Observed ranges of components in stormwater. 13 Table 3: Particle size distribution removal requirements (Portland’s Stormwater Management Manual(2008)).
21 Table 4: Stormwater treatment requirements in the city of Portland versus the state of Washington. 25 Table 5 : total number of accepted events with and without adjustment. 39 Table 6: results of the correlation for vendor 1 and 2. 57 Table 7 : Difference between three land use types ( units are mg/Lexcept for fecal coliform which is count/(100 mls)).
60 Table 8: Median and CV of TSS in the residential, mixed, commercial and open non-urban land uses. 61 Table 9: Change in the available number of stormwater events by decreasing the no-rain duration before and after an event criterion for the dry season. 66 Table 10: Change in the available number of stormwater events by decreasing the no-rain duration before and after an event criterion for the wet season. 69 Table 11: Change in the available number of stormwater events for different scenarios.
72 Table 12 :Portland's Modified Performance Standard Line data points. 74 Table 13: RMSE and Bias results for acceptable events by Portland in part I of Portland's modified performance standard line. 79 vii Table 14: RMSE and Bias results for acceptable events by Portland and Washington in part I of Portland's modified performance standard line. 79 Table 15: RMSE and Bias results for acceptable events by Portland in part II of Portland's modified performance standard line.
81 Table 16: RMSE and Bias results for acceptable events by Portland and Washington in part II of Portland's modified performance standard line. 81 Table 17: RMSE and Bias results for acceptable events by Portland in part III of Portland's modified performance standard line. 83 Table 18: RMSE and Bias results for acceptable events by Portland and Washington in part III of Portland's modified performance standard line. 83 viii Figures Figure 1: Map of Portland, Oregon with all the available gauges.
30 Figure 2: Average daily precipitation intensity for all gauges for each month, 1980-2011. 33 Figure 3: The total number of events for all gauges in each year during the dry season 35 Figure 4: The total number of events for all gauges in each year during the wet season 36 Figure 5: Histogram of the total number of events per gauge per year during the dry season. 37 Figure 6: Histogram of the total number of events per gauge per year during the wet season. 38 Figure 7: Histogram of the percentage of stormwater events per gauge per year during the dry season.
39 Figure 8: Histogram of the percentage of stormwater events per gauge per year during the wet season. 40 Figure 9: Number of gauges which follow the 30%-70% criterion compared to the total number of gauges at each year. 41 Figure 10: Number of gauges which follow the 30%-70% criterion compared to the total number of gauges at each year; when possible number of stormwater events were discarded to meet the 30%-70% criterion. 41 Figure 11: Average daily precipitation versus the number of stormwater events in each gauge for the dry season.
44 ix Figure 12: Average daily precipitation versus the number of stormwater events in each gauge for the dry season continued. 45 Figure 13: Average daily precipitation versus the number of stormwater events in each gauge for the wet season. 46 Figure 14: Average daily precipitation versus the number of stormwater events in each gauge for the wet season continued. 47 Figure 15: Histograms of the correlations between the average daily precipitation and the number of events for all gauges in the dry and wet seasons.
49 Figure 16: Correlation between the average number of events (Poisson λ) and the average daily precipitation for all gauges at each year in the dry season with a 95% confidence interval. 51 Figure 17: Correlation between the average number of events (Poisson λ) and the average daily precipitation for all gauges at each year in the wet season with a 95% confidence interval. 52 Figure 18: comparing the effects of storm depth, storm duration and antecedent dry periods on TSS removal efficiency in vendor 1. 55 Figure 19: comparing the effects of storm depth, storm duration and storm intensity on TSS removal efficiency in vendor 2 .