Brown Grease Supply Study

Transcription

1 200 S.W. Market Street, Suite 500 Portland, Oregon FAX: Brown Grease Supply Study 16 February 2011 Prepared for Clean Water Services 2550 SW Hillsboro way Hillsboro, OR K/J Project No

2 Table of Contents Executive Summary... 1 References... 6 Technical Memorandum No. 1 - Classification of Food Service Establishments based on Restaurant Categories and Quantity of Grease Production Technical Memorandum No. 2 - Interceptor Sampling and Analysis Protocol Technical Memorandum No. 3 - Data Evaluation and Conclusions List of Appendices A. Lab Summary B. Results Summary C. Food Service Establishments (FSEs) Brown Grease Supply Study, Clean Water Services 1 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

3 Executive Summary Clean Water Services (District) conducted a feasibility study (Brown Grease Supply Study) to determine the potential supply of brown grease available in its service area for codigestion in municipal anaerobic digesters. The study was comprised of three distinct efforts: Review and classification of food service establishments (FSEs) in the District s service area, Development and implementation of a sampling plan to collect and analyze brown grease samples from various categories of FSEs, and Evaluation of sampling results to determine the potential supply of brown grease in the service area. These efforts were documented in the attached series of technical memoranda. The following discussion summarizes the efforts and findings of the Brown Grease Supply Study. Background Clean Water Services source control program oversees and monitors the management of fats, oils and grease (FOG) discharge from FSEs and other commercial food production facilities (grocery stores, residential care facilities, cafeterias, etc.) in the District s service area. Existing data from the District indicates that 80% of such facilities currently have grease removal devices (GRDs indoor grease traps or outdoor grease interceptors) installed. Based on the observations of inspectors in the District s Source Control group, many of these devices are undersized for current restaurant practices, or are not connected to all drains receiving FOG during food preparation or clean-up. FOG removal at FSEs in the District s service area is expected to increase in the future as the District s enforcement activities continue and as new regulatory changes are adopted. The District has developed proposed rules which would require that all food service establishments have an outdoor GRD with a minimum volume of 1,000 gallons, and that all plumbing fixtures within kitchen/food preparation areas be connected to the GRD. Both of these activities will increase the volume of FOG collected in GRDs in the service area. The District has also evaluated the capacity of the Durham Facility to receive FOG directly in the existing anaerobic digesters. The Durham WWTP Cogeneration Expansion Project Definition and Conceptual Design Memorandum (CDM, July 2009) estimates that brown grease addition of up to 0.07 lb volatile solids (VS) per day per cubic foot (cf) can be accommodated in the existing digesters to increase methane production and generate power through cogeneration. The analysis in the Conceptual Design Memorandum indicates that this equates to 15,800 lb/day VS, or 63,800 gallons/month assuming 100% brown grease with 100% VS content. Brown Grease Supply Study, Clean Water Services 1 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

4 Classification of FSEs The first step in the feasibility study was to gather data regarding FSEs in the District s service area and classify the FSEs based on anticipated FOG production. The FSE classification process is described in Technical Memorandum 1. Data on restaurants and food preparation facilities in Washington County was obtained from Dun and Bradstreet (D&B), and merged with the District s database of FSEs in the service area. The District s database included information such as facility location, ownership, contact information, trap or interceptor size, and pumping frequency. Data from D&B included information such as facility location, parent company, local sales volume, corporate sales volume, local employment, source industrial classification (SIC) description, and North American Industry Classification System (NAICS) description. Initially, facilities were designated as very high, high, medium, or low grease producing facilities based on the experience of the District s source control staff working with the facilities, available pumping records, and annual sales volume. Once the preliminary classifications were assigned, a select group of facilities was identified for FOG sampling. These facilities were selected to provide a range of very high, high, medium, and low FOG-producing facilities in the sampling program, and to ensure that samples were collected from facilities with appropriately-sized interceptors. Sampling and Analysis Protocol Brown grease samples were collected from the inlet bays of commercial grease interceptors at 53 establishments between August 31, 2010 and October 14, Samples were collected using a DIPTSTIK-PRO core sampler made for sampling grease interceptors. Samples were collected from the center of the inlet bay of the grease interceptor where the depth of food waste and grease is believed to be representative of the average contents of the interceptor, and transferred to one gallon glass jars for transport and storage. In addition to collecting the FOG samples, District staff recorded the inlet bay dimensions; depths of the FOG, water, and solids layers in the inlet bay of the interceptor; and the dates of the current and most recent pumping. Samples were analyzed for chemical oxygen demand (COD), total solids, and volatile solids in the District s Water Quality Laboratory. The entire interceptor sample (in the original sample container) was warmed using a stirring hot plate and emulsified using an immersion blender, then a small sub-sample was withdrawn and diluted 1:200 with dilution water to determine COD concentration. Undiluted emulsified samples were analyzed for total solids (TS) and VS. The sampling and analysis protocol is described in more detail in Technical Memorandum 2. Detailed results of the FSE sampling are included in Appendix A as provided by the District s laboratory. Data Evaluation Results of the FOG analysis were used to identify brown grease production rates associated with very high, high, medium, and low grease producing FSEs. These values were then applies to facilities not included in the sampling program in order to estimate available FOG in the District s service area. Results from some facilities were biased low due to the tendency of grease to cling to the pipette and not be captured in the sample, or due to difficulty in obtaining a well-mixed sample. These results were excluded from the data analysis. Figure 1 shows the Brown Grease Supply Study, Clean Water Services 2 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

5 FOG production rates in pounds of total solids per day (lb TS/day) for the remaining sampled facilities. Of the facilities included in the data analysis, 31 had daily solids production rates of less than 12 lb TS/day, with a somewhat linear increase from the lowest-producing facility to the highestproducing facility. Daily grease production rates increased rapidly for facilities with greater than 12 lb TS/day. For purposes of identifying solids production ranges for each category, it was assumed that the range from 0-12 lb TS/day represented low, medium, and high grease producing facilities, with higher rates representing very high grease producing facilities. This breakdown for low, medium, and high producing facilities is shown in Figure 1. A detailed summary of sampling data and calculated TS, VS, and COD production is provided in Appendix B. Figure 1: Grease Production Categories Based on Facility Sampling The minimum, maximum, median, and average daily grease production (in lb TS/day) were calculated based on measured data for FSEs in the low, medium, high, and very high categories described above. The resulting solids production estimates are shown in Table 1. The percent volatile solids (% VS) in the grease samples ranged from 93% to 100%, with an average of 97.1%. Brown Grease Supply Study, Clean Water Services 3 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

6 Table 1: Total Solids Production by Category (lb TS/day) Very Medium Low Minimum Maximum Median Average Based on the sampling results, the preliminary FSE classification of very high, high, medium, and low producing facilities was adjusted to reflect actual results, and the grease production rates in Table 1 were applied to the complete list of FSEs in Appendix C. This analysis results in daily FOG production estimates shown in Figure 2. This figure shows that the anticipated level of grease production for all facilities in the service area ranges from 8,200 lb/day to 19,300 lb/day, with an average production rate of 13,000 lb/day. At 97.1% volatile solids, this equates to 12,600 lb/day VS. Figure 2: Projected Total Solids Production from FSEs in District s Service Area This figure shows that the FSEs in the service area could easily produce 12,000-13,000 lb/d TS, and may produce 20,000 lb/day or more TS given that the results include samples known to be biased low. Figure 2 shows that the solids quantity produced is greatly impacted by the high grease producing facilities, which make up the largest portion of the total solids production. The average solids production rate of 13,000 lb/d TS, collected as 7% solids in the grease Brown Grease Supply Study, Clean Water Services 4 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

7 interceptors, represents 22,700 gallons per day of brown grease or approximately seven 3,000- gallon trucks per day. Previous studies of brown grease production have shown that the number of restaurants per capita is relatively consistent throughout the country (Wiltsee, Urban Waste Grease Resource Assessment, 1998). Therefore, it is reasonable to assume that the number of FSEs per capita in the District s service area will remain constant over time. However, with the relatively low aggregate annual growth rate of approximately 2% reported in the District s 2008 Facilities Plan, variability in actual grease production has a much greater impact on the potential brown grease available for codigestion than does growth of the food service industry in the service area. Conclusions The study demonstrates that the brown grease production in the District s service area is sufficient to support codigestion of brown grease in the anaerobic digesters at the Durham facility. In terms of the District s FOG receiving program, the study supports the following conclusions: The average grease production at FSEs in the District s service area is conservatively estimated at 13,000 lb TS/day or 12,620 lb VS/day. The average concentration of total solids pumped from interceptors in the District s service area is conservatively estimated at 9.4% based on only the contents of the inlet bay, or 7% based on the total interceptor volume. If all FSEs in the service area installed interceptors and all FOG was delivered to the Durham facility, up to seven 3,000-gallon trucks per day could be anticipated. At a 90% VS destruction rate, the FOG produced in the service area could generate 170,000 CF/day of digester gas. Implementation and enforcement of new regulations regarding brown grease collection at FSEs will be critical in capturing the grease generated within the service area. Focusing the District s efforts on the high and very high grease producers will result in the greatest increase of brown grease collection. Brown Grease Supply Study, Clean Water Services 5 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

8 References Durham WWTP Cogeneration Expansion Project Definition and Conceptual Design Memorandum (CDM, July 2009) Urban Waste Grease Resource Assessment (Wiltsee,1998) Durham Advanced Wastewater Treatment Facility Plan, Flow and Load Analysis Technical Memorandum No. 1.3, (CH2M HILL, November 2008) Brown Grease Supply Study, Clean Water Services 6 Y:\Projects\2010proj\ _CWS_BrownGreaseSupplyStudy\09._Reports-Tech Memos\Executive Summary doc

9 Technical Memorandum No. 1 Classification of Food Service Establishments based on Restaurant Categories and Quantity of Grease Production

10 Kennedy/Jenks Consultants 27 July 2010 Technical Memorandum No. 1 To: From: Subject: Bruce Cordon Heather Stephens Classification of Food Service Establishments based on Restaurant Categories and Quantity of Grease Production Clean Water Services - Brown Grease Supply Study K/J Codigestion of brown grease and municipal sludge in anaerobic digesters is becoming a preferred approach to maximize methane production and energy generation and municipal wastewater treatment facilities. Clean Water Services (District) is considering implementing a fats, oils and grease (FOG) receiving facility at one of its large treatment facilities, and desires to obtain a representative estimate of the available brown grease supply from foodservice establishments (FSEs) in Washington County. Understanding the available supply of brown grease is a function of both the quantity of grease produced and the quality of FOG collected in each device. The purpose of this Technical Memorandum is to summarize the initial steps taken by the District and Kennedy/Jenks Consultants to obtain the potential quantity of grease supply from a variety of classes of FSEs. This effort included obtaining commercial data for FSEs in the County, classifying the FSEs based on the type of facility, and further categorizing the different types of facilities based on the quantity of grease production. The information presented in this memorandum will be used to estimate the available quantity of grease in Washington County. It will also be used as the basis of establishing a FOG sampling program. Initial Data Review Data on restaurants and food preparation facilities in Washington County was obtained from Dun and Bradstreet (D&B). D&B provided information on 658 FSEs in the County, which included data on the primary business description, physical address, contact information, plant/facility size, annual sales amount, etc. Additionally, the District provided information on the commercial facilities in the District s service area, which included 2,070 FSEs. The dataset from the District included information on facilities with grease traps/ interceptors, pumper, and frequency of pumping in addition to the physical address, owner, and contact information. Information from both datasets was merged and duplicate entries were removed to create a comprehensive database of FSEs in the District s service area. Classification Based on Type of Facility FSEs listed in the D&B dataset were categorized based on the type of the facility; however, FSEs in the District s dataset was not. In the merged dataset, all facilities were assigned a restaurant category similar to those used in the D&B dataset (e.g., American restaurant, y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo1_15feb2011.doc Kennedy/Jenks Consultants, Inc.

11 Kennedy/Jenks Consultants Technical Memorandum No. 1 Bruce Cordon Clean Water Services 27 July 2010 Page 2 barbeque restaurant, Bars and Lounges, Café, Cafeteria, Caterers, etc.). The FSEs were classified based on sixty-one categories of restaurants as listed in Table 1. Table 1: Restaurants Categories Classified Based on Quantity of Grease Production Restaurant Categories 1 American restaurant 2 Bar (drinking places) Low 3 Barbecue restaurant 4 Bars and lounges Medium 5 Box lunch stand Medium 6 Buffet (eating places) 7 Café Medium 8 Cafeteria Medium 9 Caterers Medium 10 Chicken restaurant Very 11 Chinese restaurant 12 Cocktail lounge Medium 13 Coffee shop Low 14 Commissary restaurant 15 Contract food services Medium 16 Delicatessen (eating places) Low 17 Diner 18 Baked Goods/Donut Places 19 Drinking places Low 20 Drive-in restaurant Medium 21 Eating places 22 Ethnic food restaurants 23 Family restaurants 24 Fast food restaurants and stands 25 Fast-food restaurant, chain 26 Fast-food restaurant, independent 27 French restaurant 28 Frozen yogurt stand Low 29 Gas Station Store Low 30 Greek restaurant Medium 31 Grills (eating places) 32 Grocery Store/Chain 33 Hotels Low 34 Hamburger stand 35 Ice cream stands or dairy bars Low 36 Ice cream, soft drink and soda fountain stands Low Estimated Grease Production y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo1_15feb2011.doc Kennedy/Jenks Consultants, Inc.

12 Kennedy/Jenks Consultants Technical Memorandum No. 1 Bruce Cordon Clean Water Services 27 July 2010 Page 3 Restaurant Categories 37 Indian/Pakistan restaurant 38 Italian restaurant 39 Japanese restaurant Low 40 Korean restaurant 41 Luncheonette 42 Mexican restaurant 43 Night clubs Medium 44 Pizza restaurants Medium 45 Pizzeria, chain Medium 46 Pizzeria, independent Medium 47 Restaurant, family: chain 48 Restaurant, family: independent 49 Saloon Low 50 Sandwiches and submarines shop Low 51 Seafood restaurants 52 Seafood shack 53 Snack bar Low 54 Soda fountain Low 55 Soft drink stand Low 56 Steak restaurant Very 57 Sushi bar Low 58 Tavern (drinking places) Medium 59 Thai restaurant 60 Vietnamese restaurant Medium 61 Wine bar Medium Estimated Grease Production Classification Based on Quantity of Grease Production A total of 1,964 FSEs in the merged dataset were then classified according to differences in quantity of grease production based on discussions with the District s staff. In order to obtain FOG samples from a range of FSEs representing a range of grease production rates, grease production was estimated as very high, high, medium, or low. These classifications were assigned based on the District s experience working with the facilities and available pumping records. Steak restaurants, chicken restaurants, and restaurants like the Cheese Cake Factory, Macaroni Grill, Hawaiian Time, Claim Jumpers, Mashiti s Teriyaki, etc. were categorized as FSEs with a very high quantity of grease production. Asian restaurants, other than Japanese and Vietnamese, American, barbeque, buffet, fast food, family style, seafood restaurants, etc. are categorized as FSEs with high quantity of grease production. Bar and lounges, cafés, cafeterias, caterers, Greek restaurants, pizzerias (where food is baked onsite), taverns, Vietnamese restaurants, etc. were categorized as FSEs with medium quantity of grease production. Coffee shops, delicatessens, frozen yogurt stand, gas station store, hotels, y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo1_15feb2011.doc Kennedy/Jenks Consultants, Inc.

13 Kennedy/Jenks Consultants Technical Memorandum No. 1 Bruce Cordon Clean Water Services 27 July 2010 Page 4 Japanese, sandwiches and submarines shops, sushi restaurants, take and bake pizza restaurants, etc. were categorized as FSEs with low quantity of grease production. However, coffee shops that have annual sales volume greater than $1M were categorized as FSEs with medium quantity of grease production. A detailed classification of restaurant categories based on quantity of grease production is shown in Table 1. In order to obtain samples from a range of facilities in each category (very high, high, medium, and low grease production), it was desired to identify approximately ten FSEs in each category to consider for participation in the sampling program. Of the 1,964 FSEs in the database, the target facilities were selected based primarily on the presence and accessibility of an appropriately-sized interceptor. Many of the FSEs in the County do not have interceptors or do not have appropriately-sized interceptors; estimates of FOG production based on sampling from these facilities would not provide a realistic estimate of the potential FOG quantities available in the County. Given this goal, fewer than 10 facilities were identified in the Medium and Low categories as these facilities do not generate large quantities of grease and often do not have devices that can be easily sampled. The list of selected facilities is shown in Table 2. This list will be used as a basis for making initial contact with the FSE owners or managers for purposes of coordinating sample collections. Table 2: Target FSEs for FOG Sampling 1 Very Medium Low Kentucky Fried Chicken (West on 185th) Jack In The Box Vietnamese (Nyberg Road) Thriftway: Meat Department (Cornell) 2 Pastini Red Robin Gloria s Café (Hillsboro) Forest Grove School 3 Muchas Gracias Baja Fresh Jennings McLaw Papa Murphy 4 Famous Daves McDonalds Dutch Bros (Cornelius) 5 Hawaiian Time ihop McMenamins (Grant Lodge) 6 Popeyes Bambuza Raccoon Lodge 7 Claim Jumper Thriftway - Deli and Bakery 8 PF Chang Romano's Macaroni Grill 9 Outback Steakhouse Ruby Tuesday 10 Providence St. Vincent's Hospital Gustav's Bar and Grill 11 Buffalo Wild Wings Red Lobster 12 Panda Express Enclosure: (1) Starbucks (Walker and 154th) Subway (TV way) y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo1_15feb2011.doc Kennedy/Jenks Consultants, Inc.

14 Technical Memorandum No. 2 Interceptor Sampling and Analysis Protocol

15 Kennedy/Jenks Consultants 4 August 2010 Technical Memorandum No. 2 To: From: Subject: Bruce Cordon Heather Stephens Interceptor Sampling and Analysis Protocol Clean Water Services - Brown Grease Supply Study K/J Clean Water Services (the District) is conducting a feasibility study to determine the potential supply of brown grease available in its service area for codigestion in municipal anaerobic digesters. The purpose of this memorandum is to document the sampling and analytical approach to be used to collect and evaluate samples from grease interceptors and traps at food service establishments in the service area. Sample Collection Samples will be collected from grease interceptors using a DIPSTICK-PRO TM core sampler made for sampling grease interceptors. The core sampler is a 10-foot tube made of clear resin with a valve located at the base of the sampler. The sampler is marked at 12-inch intervals; additional graduated indicators will be added by District staff to allow for accurate measurements of the depth of material in the interceptor. Samples will be collected from the center of the inlet bay of the grease interceptor, where the depth of food waste and grease is believed to be representative of the average contents of the interceptor. Samples collected from grease interceptors will be transferred to one gallon glass jars, stored in a cooler, and transferred to the District s Water Quality Laboratory with an appropriate Chain of Custody. A log will also be maintained noting the ph, FOG depth, grey water depth, food waste depth, and inlet bay dimensions (or volume) for each sample site. Initially, it is anticipated that approximately three facilities will be sampled per day, two days per week (Tuesday and Thursday). After beginning the sampling program, it may be possible to increase the number of facilities sampled per day. Sampling will be conducted on Tuesday and Thursday to maximize the opportunity for immediate processing of the interceptor sample. If the sample cannot be processed immediately, it will be refrigerated upon arrival at the Water Quality Laboratory. Samples will be collected shortly before scheduled cleaning to maximize the volume of material in the interceptor. District staff will identify the date of the last cleaning (through routine reporting or through contact with the owner or manager of the facility) to determine the calendar period represented by the interceptor sample. District staff will also determine whether there were any unique circumstances during this period (e.g., major closure or major event), changes in menu offerings or food preparation practices, or other activities that may have impacted the quantity of material collected in the interceptor. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo2_15feb2011.docx Kennedy/Jenks Consultants, Inc.

16 Kennedy/Jenks Consultants Technical Memorandum No. 2 Clean Water Services 4 August 2010 Page 2 Sample Analysis The entire sample from the interceptors (in the original sample container) will be warmed using a stirring hot plate sufficiently to liquefy solidified grease, then emulsified using an immersion blender. Once the sample is emulsified, a small sub-sample will be immediately withdrawn and diluted 1:200 with dilution water in a 50 ml vial. An aliquot of the diluted sample will then be placed in a mg/l HACH COD reaction tube and will be measured for COD using the HACH COD method. Undiluted emulsified samples will also be analyzed for total solids and volatile solids. Four test samples were collected from high FOG-producing establishments and analyzed by the District to verify the methodology outlined above. During the testing period, tests were conducted on each interceptor sample four to five times over the course of 11 days. It was noted that for one of the samples, the COD concentration declined steadily each time the sample was re-tested. It is suspected that the heating of the sample could have resulted in biological activity that degraded the COD, though this was not observed in the samples from the other three establishments. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo2_15feb2011.docx Kennedy/Jenks Consultants, Inc.

17 Technical Memorandum No. 3 Data Evaluation and Conclusions

18 Kennedy/Jenks Consultants 24 January 2011 Technical Memorandum No. 3 To: From: Subject: Bruce Cordon, Clean Water Services Heather Stephens, Kennedy/Jenks Consultants Greg Chung, Kennedy/Jenks Consultants Data Evaluation and Conclusions Clean Water Services - Brown Grease Supply Study K/J Clean Water Services (District) is conducting a feasibility study to determine the potential supply of brown grease available in its service area for codigestion in municipal anaerobic digesters. The purpose of this memorandum is to document the results of sampling and analysis of representative food service establishments (FSEs) in the District s service area, and to present conclusions regarding the potential supply of brown grease in the service area. Background Clean Water Services source control program oversees and monitors the management of fats, oils and grease (FOG) discharge from FSEs and other commercial food production facilities (grocery stores, residential care facilities, cafeterias, etc.) in the District s service area. Existing data from the District indicates that 80% of such facilities currently have grease removal devices (GRDs indoor grease traps or outdoor grease interceptors) installed. Based on the observations of inspectors in the District s Source Control group, many of these devices are undersized for current restaurant practices, or are not connected to all drains receiving FOG during food preparation or clean-up. FOG removal at FSEs in the District s service area is expected to increase in the future as the District s enforcement activities continue and as new regulatory changes are adopted. The District has developed proposed rules which would require that all food service establishments have an outdoor GRD with a minimum volume of 1,000 gallons, and that all plumbing fixtures within kitchen/food preparation areas be connected to the GRD. Both of these activities will increase the volume of FOG collected in GRDs in the service area. The District has also evaluated the capacity of the Durham Facility to receive FOG directly in the existing anaerobic digesters. The Durham WWTP Cogeneration Expansion Project Definition and Conceptual Design Memorandum (CDM, July 2009) estimates that brown grease addition of up to 0.07 lb Volatile Solids (VS) per day per cubic foot (cf) can be accommodated in the existing digesters to increase methane production and generate power through cogeneration. The analysis in the Conceptual Design Memorandum indicates that this equates to 15,800 lb/day VS, or 63,800 gallons/month assuming 100% brown grease with 100% VS content. Previous technical memoranda summarized the methodology used to characterize FSEs regarding potential brown grease generation (Technical Memorandum No. 1) and the sample collection and analytical approach (Technical Memorandum No. 2). The following discussion y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

19 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 2 summarizes the FOG production measured at a range of FSEs in the service area, and projects the resulting potential supply of brown grease. Sampling Approach Brown grease samples were collected from the inlet bays of commercial grease interceptors at 53 establishments between August 31, 2010 and October 14, Samples were collected using a DIPTSTIK-PRO core sampler made for sampling grease interceptors, and samples were analyzed in the District s water quality laboratory. In addition to collecting the sample as described in Technical Memorandum No. 2, District staff recorded the duration of brown grease collection (from most recent pumping to sample collection) and the inlet bay dimensions. In addition, because the waste is generally stratified in the interceptors, staff also recorded the depths of the FOG), water, and solids layers in the inlet bay of the interceptor. Once collected, samples were analyzed for total solids content, volatile solids content, and chemical oxygen demand (COD). Of the 53 samples collected, 51 were analyzed for inclusion in the study. Two samples were excluded from the analysis based on the recommendations of District staff. Table 1 shows the facilities included in the brown grease sampling effort, along with their initial classification as a very high, high, medium, or low brown grease-producing establishment. These classifications were established for a range of FSEs (café, diner, fast food, hotel, etc.) based on the experience and observations of the District s inspection staff. A detailed account of facility classification is included in Technical Memorandum No. 1. Table 1: FSEs Included in FOG Sampling Program Establishment Kentucky Fried Chicken #349 Kentucky Fried Chicken #343 Elmer s 1250 NW Waterhouse Bugatti s 2950 SW Cedar Hills Outback 8660 SW Tualatin-Sherwood Rd Romanos SW 72 nd Bugatti s 2 Pastini El Pollo Loco Olive Garden Sanchez Taqueria Famous Dave s McDonalds # Sonic Drive-In Jack in the Box #7114 Panda Express 1 Estimated Grease Production Very Very Very Very Very Very Very Very Very Very Very Very y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

20 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 3 Establishment Burger King Red Robin #081 Baja Fresh Cedar Hills Chipotle Cedar Hills Wendy s Baseline Rd. Shari s Murray Blvd. Denny s Scholl s Ferry Panda Express -2 Applebees Village Inn Sonic Drive-In 2 Carl s Jr. Chevy s IHOP Muchas Gracias 1 Panda Express 3 Noah s Bagels Muchas Gracias 2 McDonald s #26244 Taco Bell #2403 Noodles & Company Fred Meyer Panda Express 4 Marie Calendar s Krispy Kreme Wendy s 2 Bales Thriftway Meat/Seafood Bales Thriftway Deli/Bakery PF Chang s Safeway La Isla Bonita Reedville Café Hot Seat Papa Murphy s Pizza Estimated Grease Production Medium Medium Low Sampling Results Detailed results of the restaurant sampling are included in Appendix A as provided by the District s laboratory. Results include duplicate and spike samples where appropriate. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

21 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 4 Many of the samples analyzed in the laboratory were biased low due to the tendency of grease to cling to the pipet and not be captured in the sample, or due to difficulty in obtaining a wellmixed sample. Comments included in the laboratory analysis indicate where the results are estimated or questionable (noted as E or Q in the Data Qualifier field in the laboratory data). In most cases, these samples are identified as being biased low when some grease remained stuck to the outside of the pipet, or biased grossly low when a significant amount of grease remained stuck to the outside of the pipet. For purposes of analyzing data and using the results to project available grease by type of FSE, results identified as grossly biased low were excluded from the data evaluation. Results from 12 of the 51 facilities were noted as grossly biased low; these facilities were anticipated to have high (10 facilities) or very high (2 facilities) grease production. Results reported as biased low were included in the analysis, with the understanding that this results in a conservative estimate of available brown grease. In order to extrapolate data from the facilities that were sampled to other FSEs in the service area that were not sampled, it was necessary to identify grease production rates associated with very high, high, medium, and low grease producers. Table 2 shows the grease production rates for those facilities included in the analysis, represented as pounds of TS per day. This value was calculated as follows: Table 2: Brown Grease Sampling Results: lbs TS/day Facility lb TS/d Bales Thriftway Meat/Seafood 0.30 Noah's Bagels 0.89 McDonalds # Panda Express Pastini 1.98 Starbucks # Starbucks # Burger King 2.33 La Isla Bonita 2.36 Wendys Jack in the Box # Denny's SW Scholls Ferry Rd 4.07 Red Robin # Muchas Gracias y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

22 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 5 Facility lb TS/d Muchas Gracias Marie Calendar s 5.44 Bales Thriftway Deli/Bakery 5.56 Village Inn 5.93 Chipotle SW Cedar Hills Blvd 6.15 Chevy's 6.20 Safeway (1/2 Store) 6.68 Wendy's W Baseline Rd 7.11 Sonic Drive-In 7.92 IHOP 8.46 KFC # Panda Express Panda Express Bugatti's Baja Fresh SW Cedar Hills Blvd 9.93 Romanos SW 72nd Ave Bugatti's SW Cedar Hills Blvd Famous Dave's Panda Express SW Baler Way Olive Garden Reedville Café KFC # Elmer's NW Waterhouse Ave Sanchez Taqueria PF Chang's Of the facilities included in the data analysis, 31 had daily solids production rates of less than 12 lb TS/day, with a somewhat linear increase from the lowest-producing facility (Bales Thriftway) to the highest-producing facility (Famous Dave s). Daily grease production rates increased rapidly for facilities with greater than 12 lb TS/day. For purposes of identifying solids production ranges for each category, it was assumed that the range from 0-12 lb TS/day represented low, medium, and high grease producing facilities, with higher rates representing very high grease producing facilities. This breakdown for low, medium, and high producing facilities is shown in Figure 1. A detailed summary of sampling data and calculated TS, VS, and COD production is included as Appendix B. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

23 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 6 Figure 1: Grease Production Categories Based on Facility Sampling The minimum, maximum, median, and average daily grease production (in lb TS/day) were calculated based on measured data for FSEs in the low, medium, high, and very high categories described above. The resulting solids production estimates are shown in Table 3. The percent volatile solids (% VS) in the grease samples ranged from 93% to 100%, with an average of 97.1%. Table 3: Total Solids Production by Category (lb TS/day) Very Medium Low Minimum Maximum Median Average Projected Brown Grease Quantities The objective of this project was to use data from Clean Water Services service area to project the quantity of brown grease available. This was achieved by applying the projected grease y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

24 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 7 quantities in Table 3 to facilities in the service area based on anticipated grease production. As described in the Sampling Approach, facilities were classified as very high, high, medium, or low grease producing facilities early in the project based on the experience of the District s source control staff. These classifications were reviewed based on sampling data to determine whether adjustments were appropriate. In most cases, the sampling results confirmed the facility designation. The classifications and sampling results were also compared with gross receipts (available for approximately 30% of the facilities in the service area), which provides an approximate estimate of the relative volume of food preparation at similar types of facilities. Table 4 shows the initial and final classifications of the sampled facilities. Table 4: Brown Grease Sampling Results: lbs TS/day Facility lb TS/d Initial Facility Classification Classification Based on Sampling Bales Thriftway Meat/Seafood 0.30 Medium Low Noah's Bagels 0.89 Medium Low McDonalds # Medium Low Panda Express Medium Low Pastini 1.98 Very Low Starbucks # Medium Low Starbucks # Medium Low Burger King 2.33 Medium Low La Isla Bonita 2.36 Medium Low Wendys Medium Low Jack in the Box # Medium Medium Denny's SW Scholls Ferry Rd 4.07 Medium Medium Red Robin # Medium Medium Muchas Gracias Medium Medium Muchas Gracias Medium Medium Marie Calendar s 5.44 Medium Medium Bales Thriftway Deli/Bakery 5.56 Medium Medium Village Inn 5.93 Medium Medium Chipotle SW Cedar Hills Blvd 6.15 Medium Medium Chevy's 6.20 Medium Medium Safeway (1/2 Store) 6.68 Medium Medium Wendy's W Baseline Rd 7.11 Medium Sonic Drive-In 7.92 Medium IHOP 8.46 Medium KFC # Very Panda Express Medium Panda Express Medium y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

25 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 8 Facility lb TS/d Initial Facility Classification Classification Based on Sampling Bugatti's Very Baja Fresh SW Cedar Hills Blvd 9.93 Medium Romanos SW 72nd Ave Very Bugatti's SW Cedar Hills Blvd Very Famous Dave's Very Panda Express SW Baler Way Medium Very Olive Garden Very Very Reedville Café Medium Very KFC # Very Very Elmer's NW Waterhouse Ave Very Very Sanchez Taqueria Very Very PF Chang's Medium Very Additional changes to facility classifications are described below: American and Family Restaurants: These were originally anticipated to be high grease producers, but were changed to medium based on the results of sampling at facilities such as Denny s, Village Inn, Chevy s, and Marie Callendars. Facilities with higher than typical gross receipts were left with high designations, and the Cheesecake Factory (with one of the largest volumes of sales in the County) remained very high. Cafeterias serving large quantities of meals (Pacific University, other schools, correctional facilities, and hospitals) were estimated to be high grease producers; other cafeterias were estimated to be medium grease producers. Of the two Kentucky Fried Chicken restaurants tested, one was in the high category and one was very high. The sample from the restaurant designated as high was noted to be biased low, so the initial designation of very high for chicken restaurants was maintained in the final analysis. Of the four Chinese restaurants sampled, two had very high grease production and two had high grease production. One of the very high grease producing facilities (PF Chang s) has one of the highest volumes of sales of the restaurants in the County (more than ten times higher than the other facilities sampled). This restaurant was given a designation of very high, but other Chinese restaurants were anticipated to be high grease producers. The initial and final anticipated grease production rates for all known FSEs in the District s service area are shown in Appendix C. Figure 2 shows the breakdown of anticipated grease production rates, along with the total number of FSEs in each category. Only 4.2% of the facilities are anticipated to be very high grease producers. The facilities are split fairly evenly y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

26 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 9 among the other three categories with 36% expected to be high grease producers, 30% medium grease producers, and 30% low grease producers. Figure 2: Breakdown of Anticipated FSE Grease Production in District s Service Area Applying the grease production rates in Table 3 to the complete list of FSEs in Appendix C results in the daily grease production (lb TS/day) shown in Figure 3. This figure shows that the anticipated level of grease production for all facilities in the service area ranges from 8,200 lb/day to 19,300 lb/day, with an average production rate of 13,000 lb/day. At 97.1% volatile solids, this equates to 12,600 lb/day VS. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

27 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 10 Figure 3: Projected Total Solids Production from FSEs in District s Service Area This figure shows that the FSEs in the service area could easily produce 12,000-13,000 lb/d TS, and may produce 20,000 lb/day or more TS given that the results include samples known to be biased low. Figure 3 shows that the solids quantity produced is greatly impacted by the high grease producing facilities, which make up the largest portion of the total solids production. This projected solids quantity compares well with the 15,800 lb/d VS brown grease capacity in the Durham Facility digestion system identified in the Durham WWTP Cogeneration Expansion Project Definition and Conceptual Design Memorandum. The average TS concentration measured in the inlet bays of the grease interceptors was 9.4%. When interceptors are pumped and conveyed to the treatment facility, the contents of the pumper truck will include water from both the inlet and outlet bays. Based on information provided by the District s source control department, the outlet bay adds approximately 37% additional volume, and is assumed to contain minimal grease or solids in a properly functioning interceptor. Therefore, accounting for the volume of the outlet bay, the average mixed contents of pumped interceptors is anticipated to be 7% TS. The average solids production rate of 13,000 lb/d TS, collected as 7% solids in the grease interceptors, represents 22,700 gallons per day of brown grease or approximately seven 3,000-gallon trucks per day. The average solids concentration of 7% is slightly lower than that typically seen in average FOG deliveries at other facilities, which would be expected given that the data includes samples known to be biased low. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

28 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 11 Other Potential Sources There are several other potential sources of industrial grease/solids in the District s service area that could or should be considered in the FOG receiving program. These sources were identified through discussion with District staff and review of the District s 2008 Facilities Plan (Flow and Load Analysis Technical Memorandum No. 1.3, CH2M HILL). St. Vincent Hospital prepares thousands of meals per day to serve patients and in several commercial restaurants and cafeterias at the hospital. The existing interceptor is undersized, and would need to be pumped multiple times per day to maintain proper functioning. St. Vincent is currently installing a new adequately-sized interceptor, and has designed the interceptor around an anticipated FOG load of 2,900 lb/month (95 lb/day). The Facility Plan reviewed available loading data for large industrial customers, and concluded that Pacific Foods is the only industrial contributor with significant loads. The average annual TSS and COD loadings from Pacific Foods for the years are 595 lb/day and 4,867 lb/day, respectively. It is unclear what portion of the waste stream could be separated and conveyed directly to the FOG receiving facility, or whether the solids produced at Pacific Foods are suitable for receiving directly in the digesters at Durham. Other smaller industrial facilities in the service area could also contribute grease or solids to the facility. Food processing facilities such as Reser s Fine Foods, New Season Foods (formerly Birdseye) and Beaverton Foods may have waste streams suitable for discharge at a FOG receiving facility. Information regarding potential solids or grease production was not available for these facilities, however since they were not identified as significant industrial dischargers in the Facility Plan; it is assumed that they would not significantly impact projections of available grease quantities. Future Grease Production Previous studies of brown grease production have shown that the number of restaurants per capita is relatively consistent throughout the country (Wiltsee, Urban Waste Grease Resource Assessment, 1998). Therefore, it is reasonable to assume that the number of FSEs per capita in the District s service area will remain constant over time. Population growth in both the Rock Creek and Durham service areas was documented in the District s 2008 Facilities Plan. Table 5 shows projected population under the medium growth scenario based on Metro s 2020 population forecast. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

29 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 12 Table 5: Projected Population and Growth Rate Population by Service Area Durham Rock Creek Total Growth Rate , , , , , , % , , , % , , , % , , , % , , , % Applying these growth rates results in the projected grease quantities shown in Figure 4. The figure shows the baseline solids along with potential solids including additional industrial sources. It also includes error bars showing how this projection would change with a 5% variation in anticipated growth rates. With the relatively low aggregate annual growth rate of approximately 2%, variability in actual grease production has a much greater impact on the potential brown grease available for codigestion than does growth of the food service industry in the service area. Figure 4: Projected Increase in TS Production based on Service Area Growth y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.

30 Kennedy/Jenks Consultants Technical Memorandum No. 3 Clean Water Services 24 January 2011 Page 13 Conclusions The study demonstrates that the brown grease production in the District s service area is sufficient to support codigestion of brown grease in the anaerobic digesters at the Durham facility. In terms of the District s FOG receiving program, the study supports the following conclusions: The average grease production at FSEs in the District s service area is conservatively estimated at 13,000 lb TS/day or 12,620 lb VS/day. The average concentration of total solids pumped from interceptors in the District s service area is conservatively estimated at 9.4% based on only the contents of the inlet bay, or 7% based on the total interceptor volume. If all FSEs in the service area installed interceptors and all FOG was delivered to the Durham facility, up to seven 3,000-gallon trucks per day could be anticipated. At a 90% VS destruction rate, the FOG produced in the service area could generate 170,000 CF/day of digester gas. Implementation and enforcement of new regulations regarding brown grease collection at FSEs will be critical in capturing the grease generated within the service area. Focusing the District s efforts on the high and very high grease producers will result in the greatest increase of brown grease collection. y:\projects\2010proj\ _cws_browngreasesupplystudy\09._reports-tech memos\cws_grease_tech memo3_15feb2011.doc Kennedy/Jenks Consultants, Inc.