BOXELDER SANITATION DISTRICT

Transcription

1 WASTEWATER UTILITY PLAN AMENDMENT for the BOXELDER SANITATION DISTRICT March 14, 2018

2 Forward Boxelder Sanitation District is planning to expand their Wastewater Treatment Plant. As a result of the planning effort for the expansion project, updated information pertinent to the Utility Plan that is dated May 31, 2010 has been amended. Specifically, the amendments are to the following sections of the Utility Plan. Section II.E Population Projections Section III Wastewater Characteristics Section VI Wastewater System Planning Process Selection The Selected Plan Implementation Section VII Management and Financial Plans Appendix I Monthly Data and Preliminary Effluent Limits UTILITY PLAN UPDATE / 1

3 Replace Section II.E with the following: E. POPULATION PROJECTIONS Successful and accurate planning for wastewater collection and treatment facilities depends a great deal on forecasting future flows and loadings. Estimating future flows requires analysis of the land contained within the District s service area relative to land use and population projections. From these estimates, one can begin to estimate the corresponding flows and loadings. Although population and land use forecasting may appear to be straightforward, many variables may change in the future and alter the initial estimates. General economic trends and local politics play a large role in land development and consequently have a major impact on the District s future planning. A concerted effort was made to make the projections accurate and reliable, but also flexible to allow for potential changes. The timing for when new facilities are needed becomes difficult to forecast since assumptions must be made as to the rate of growth over time. The current residential population is about 18,200 based upon 6,094 residential and commercial taps. Projections for the 20 year planning period were estimated at 200, 280 and 320 equivalent taps per year. In addition, a 3.5% rate of growth was analyzed for comparison. The varying rates extended to 2050 are shown on Figure II 2. FIGURE NO. II 2 BOXELDER TAP PROJECTION UTILITY PLAN UPDATE / 2

4 The northeast portion of the Fort Collins growth area is projected to grow due to available undeveloped land. This growth is within the Boxelder District service area. Table II 2 is a listing known and potential development projects. Table II 2 Potential Future Development PROJECT NAME NO. WDR STATUS Timbervine SF 167 developed East Ridge SF, MF 1000 developed and future phases Wildwing II SF 217 developed and future phases Waters Edge SF 356 approved Fox grove SF 67 under construction Serratoga Falls SF 524 future Waterfield _SF 197 future Trail Head multi family, MF 99 In review Harmony Ridge SF, COMM, SCH 1600 developed and future Buffalo Creek SF 550 future Fisher Property SF 750 In review Gateway@ Prospect SF, MF, COMM 517 future Teal Creek SF 81 future Streamside SF 128 future The Preserve SF 90 future The Auburn SF 34 future Allison Estates SF 50 future Liberty Farms SF 300 future Total WDR s 6,727 SF Single Family MF Multi Family COMM Commercial SCH School UTILITY PLAN UPDATE / 3

5 Replace Section III with the following: III. Wastewater Characteristics Wastewater is not uniform in character and changes from location to location and time to time. Several parameters are generally used to define the amount and strength of wastewater. Examining the influent wastewater characteristics is essential prior to assessing the efficiency of an existing wastewater treatment facility or planning for the future treatment requirements. The EPA defines the minimum level of effluent quality that must be attained by secondary treatment of wastewater. Presently, acceptable secondary effluent is generally defined in terms of flow, biochemical oxygen demand (BOD), total suspended solids, ammonia (NH 3 ), E Coli, and ph. Since 2007, the District has improved quality control on lab sampling and testing in an effort to insure better accuracy. This increased vigilance is apparent in the records over the past two years as illustrated later in this chapter. Over the past 24 months, organic and solids concentrations are higher than in previous years records. Subsequently, these more recent values were used in making projections of future loadings. FLOW The quantity of wastewater entering the plant largely governs the hydraulic capacity of the plant. Representative flow data revealing average, minimum, and peak flows is required to accurately size treatment facilities and determine whether existing facilities are at their design capacity. The 36 month influent flow history from 2015 through 2017 is shown on Table lii 1. Flow data for this study was obtained from the influent flow readings from 2015 through 2017 and is illustrated on the Figure III 1. Monthly Data for flow, BOD, Total Suspended Solids and Ammonia Nitrogen for the study years is included as Exhibit 1 in Appendix 1. Table III 1 Influent Flow History 36 month span from Jan 2015 thru Dec 2017 Influent Flow (MGD) Max Day Max Month Average Month UTILITY PLAN UPDATE / 4

6 Figure III 1 Influent Flow History Infiltration and Inflow (I/I) I/I can present problems for many wastewater treatment plants. Inflow is generally defined as surface water entering the system through poorly constructed manhole rings and covers, storm sewer cross connections, and roof leaders or basement sumps connected and discharging into the sewer. Influent flow data, which exhibits extraordinary peak flows during or immediately following storm events is typically due to inflow into the sewer system. Infiltration generally consists of groundwater entering the sewer system via cracked sewer lines, open joints, and poor manhole connections. Infiltration. EPA uses 120 gpcd or less for typical per capita flow calculations. Average flows over that value (120 gpcd) are considered potentially excessive infiltration. The Colorado Department of Public Health and Environment (CDPHE) guidelines advise use of about 80 gpcd for planning for residential contributions, only. Knowing that I&I is a component of the current flows, I&I was determined by taking the difference between the calculated per capita flows and recorded plant flows. For the 2016, the average flow is 1.97 MGD and the calculated flow is 1.37 MGD based on design criteria (75gpcd and 3.0 persons per SFE), leaving a difference of.598 MGD for I&I. UTILITY PLAN UPDATE / 5

7 With an equivalent contributing population of 18,282 (3,640 taps at 3.0 people per tap) the average per capita flow is 107 gpcd which is below the 120 gpcd guideline. The District has an active sewer rehabilitation program to line clay sewer improve structural deficiencies and reduce infiltration. Approximately 20,000 feet was lined in and another 25,000 feet will be lined in Inflow. Wastewater flows during wet weather periods also provide insight into the occurrence of extraneous flows into a given collection system in the form of inflow which enters the system directly through leaking manholes, storm drain cross connections, and other direct connections to the collection system. At the District, wet weather (instantaneous) flow peaks at the plant are about 2.1 times the average flow rate. The peak (instantaneous) flowrates experienced during or immediately after wet weather periods have been 4.2 mgd or less. This flow rate translates to an instantaneous peak per capita flow rate of 229 gpcd. The EPA guideline for potentially excessive inflow rates into a collection system is 260 gpcd during wet weather periods. Subtracting the 107 gpcd average flow from the 229 gpcd figure derived above leaves an effective wet weather flow rate of about 122 gpcd which is in an acceptable range. Regarding new development, the District has a program which allows them to inspect new sewer lines and manhole construction before taking ownership of the new system. The District has the option of rejecting the work and requiring the developer to improve or change the construction in order to meet the District s standards. With recent ongoing efforts in the areas of sewer line maintenance, replacement, and continual inspection of new sewer work, the District will, over time, achieve reduction in the amount of I/I into the system. BIOCHEMICAL OXYGEN DEMAND Bacteria placed in contact with organic material will utilize the organic material as a food source. Eventually the organic material will be oxidized to products such as nitrogen, CO 2, inert matter, and water. The amount of oxygen used in this process is called the biochemical oxygen demand and is considered to be a measure of the organic content of the waste. The amount of oxygen absorbed during the first five days of this process is known as the 5 day biochemical oxygen demand (BOD 5 ). The 2015 through 2017 average value at the District is 215 mg/l, as shown in Table III 2. Table III 2 BOD History 36 month span from Jan 2015 thru Dec 2017 BOD, mg/l BOD, lbs. Max Day Max Month Average Month Loading data for this study was obtained from influent BOD readings from 2015 through 2017 and is shown on Figure III 2. UTILITY PLAN UPDATE / 6

8 Figure III 2 Influent BOD History TOTAL SUSPENDED SOLIDS Wastewater from a primarily residential service area typically has a suspended solids value of approximately 0.20 pounds per capita per day. The typical average concentration of suspended solids in raw domestic wastewater is approximately 250 mg/l with a range of from 200 to 500 mg/l. The data is shown on Table III 2. Table III 2 Suspended Solids Loading (TSS) 36 month span from Jan 2015 thru Dec 2017 TSS, mg/l TSS, lbs. Max Day Max Month Average Month UTILITY PLAN UPDATE / 7

9 The average TSS concentration was 200mg/l which translates to a daily load of 3,750lbs/day. The range of influent values for the Boxelder system is shown on the Figure III 3. Figure III 3 Influent Suspended Solids History AMMONIA NITROGEN Typical domestic wastewater contains both organic and ammonia nitrogen. The levels of these two constituents vary with the strength of the waste stream, but it is generally observed that the Total Kjeldahl Nitrogen (TKN) content will be in the neighborhood of 50 mg/l, with a range of from 30 mg/l (weak) to 85 mg/l (strong). Of this average value, about 20 to 25 mg/l is usually organic nitrogen, and the remaining 25 to 30 mg/l is free ammonia. Recent sampling indicates the influent stream has an average TKN value of 16.4 mg/l with a range of from 13 to 21 mg/l. At an average 16.4 mg/l, the daily Total Nitrogen load is 349 lbs/day as shown in Figure III 4. UTILITY PLAN UPDATE / 8

10 Figure III 4 Ammonia History TEMPERATURE, PH AND SELENIUM Other wastewater parameters that affect treatability include the water temperature, its ph value and, where nitrification is concerned, the amount of hardness (alkalinity) in the influent stream. Table II 4 summarizes 2016 temperature and ph values: UTILITY PLAN UPDATE / 9

11 Table III 4 Influent Temperature and ph Values Month Temp C ph Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec The foregoing values all fall into a typical range for typical treatment plant. Other constituents of concern are selenium and sulfates. The PEL attached lists a 2.5 ug/l stream standard limit average effluent selenium was 1.3 ug/l, so it anticipated the any future limits will be met. FUTURE FLOWS AND LOADS Using the population projections from Section II, the population will grow from 18,282 in 2016 to 41,744 in Considering the information developed above, wastewater flow and load projections can be derived as shown on the following tables. For purposes of future projections used in this report, it is assumed that future growth in new areas with new sewerage systems will have domestic contribution rates of 75 gallons per capita per day (gpcd). The resulting flows and loads are described below: Hydraulic Loading 1. Residential a. The District currently uses 2.54 persons per household. State Demographer s Office estimates 2.42, 2.37, and 2.92 for Larimer County, Fort Collins, and Timnath, respectively. Although outside the service area, Wellington is estimated at 2.88 and Windsor is estimated at For planning purposes, the Boxelder staff decided to use 3.0 persons per household. b. The District currently uses 75 gallons per capita per day. The Boxelder staff decided to continue using 75 gallons per capita per day for planning purposes, as shown in Table III 3. Table III 3 Residential Design Flows Residential Flows 3.0 persons per household 75 gallons per capita per day UTILITY PLAN UPDATE / 10

12 2. Commercial/Industrial The District currently uses 500 gallons per acre per day for both commercial and industrial areas. The Colorado Department of Public Health & Environment (CDPHE) Water Pollution Control Policy Number WPC DR 1 indicates that absent (1) data from the existing system, (2) adopted flow criteria from the utility, or (3) basis of design criteria from a similar utility; the contributions should be no less than 1,500 gpd per acre for commercial land and 2,000 gpd per acre for industrial land. The Boxelder staff indicated they didn t think they had data to support the 500 gpd per acre design flow and wanted to evaluate the system build out flows using the CDPHE criteria of 1,500 gpd per acre for commercial land and 2,000 gpd per acre for industrial land. 3. Evaluation of Current Commercial/Industrial Flows The District supplied water consumption data for commercial and industrial users from January of 2015 through September of The maximum average monthly flow was 433,710 gpd for August of 2015 and 486,400 gpd for September of Information from the District s GIS database indicates there is approximately 2,125 gross acres of commercial and industrial properties currently connected to Boxelders collection system. Assuming all the potable water flow to the commercial and industrial properties is discharged to the collection system, the resultant loading to the wastewater treatment plant is (486,400 gallons per day divided by 2,125 gross acres) equal to 228 gallons per day per gross acre. This information would support the Districts current use of using 500 gpd/acre for commercial and industrial properties (as shown in table III 4), instead of the higher CDPHE values of 1500 and 2000 gpd/acre, respectively. As a comparison, the City of Thornton uses 600 gpd/acre for commercial and industrial properties. Table III 4 Commercial/Industrial Design Flows Commercial/Industrial Flows 500 gallons per day per acre Commercial 500 gallons per day per acre Industrial 4. Estimate of Maximum Hydraulic Capacity of Wastewater Treatment Plant at 20 Year planning Future flows were projected from 2016 to 2040 using 2016 as a basis. SFE s were projected at a 3.5% growth rate. The average annual flow to the plant in 2016 was 1.97 MGD and was used as the starting point for projecting future flows. Knowing that I&I is a component of the current flows, I&I was determined by taking the difference between the calculated per capita flows and recorded plant flows. For 2016, the average flow is 1.97 MGD and the calculated flow is 1.37 MGD based on design criteria (75gpcd and 3.0 persons per SFE), leaving a difference of.598 MGD for I&I. Based on a current 2016 population of 18,282 persons the average daily per capita flow is 108 gal per capita per day. The average multiplier for Max Month Average is UTILITY PLAN UPDATE / 11

13 Since I&I will reduce in the future as new sewers will be constructed to higher leakage standard, I&I is projected at 2% growth and flow is projected at 3.5%. Table III 5 shows the flow projections from 2016 to The average annual flow is 4.1 MGD, a maximum month flow of 6.0 MGD, and a peak flow of 9.6 MGD at 20 year buildout. Table III 5 Flow Projections Number of taps with 3.5% Population Equivalent at 3.0 per/tap Assumed 2% increase in I&I (gal/day) Flow at 75 gpcd 3.5% growth Max Month Avg. day x1.46 Flow at 75 gpcd 3.5% growth ,094 18,282 1,371, , ,307 18,922 1,419, , ,528 19,584 1,468, , ,757 20,270 1,520, , ,993 20,979 1,573, , ,238 21,713 1,628, , ,491 22,473 1,685, , ,753 23,260 1,744, , ,025 24,074 1,805, , ,305 24,916 1,868, , ,596 25,789 1,934, , ,897 26,691 2,001, , ,208 27,625 2,071, , ,531 28,592 2,144, , ,864 29,593 2,219, , ,210 30,629 2,297, , ,567 31,701 2,377, , ,937 32,810 2,460, , ,320 33,959 2,546, , ,716 35,147 2,636, , ,126 36,377 2,728, , ,550 37,651 2,823, , ,989 38,968 2,922, , ,444 40,332 3,024, , ,915 41,744 3,130, , Table III 6 shows the 20 year hydraulic design criteria. Table III 6 20 year flow design criteria Estimate of Maximum Hydraulic Capacity of Wastewater Treatment Plant at 20 Year Buildout 4.1 MGD Annual Average Flow (AAF) 6.0 MGD Maximum Month Flow (MMF) 9.6 MGD Peak Flow (PF) UTILITY PLAN UPDATE / 12

14 Currently, when new commercial or industrial customers are added they each become a commercial account based on the size of their water meter. Each meter size has a multiplier of the single family equivalent (SFE) unit. In determining future projections, it is difficult to project whether new customers will be residential, commercial or industrial users. Therefore, rather than attempting to determine growth for each type of user, the projections are based on SFE s, which can be either residential, commercial or industrial. The projections are based on 2017 SFE s of 6,307 and 2040 SFE of 13,915, there are 7,608 SFEs available with the plant expansion. Figur e III 4 show s the futur e flow proje ctions for the plant. Figure III 4 Future Flow and Existing Plant Capacity Organic Loading 1. Estimate of Maximum Organic Loading for Wastewater Treatment Plant at System Buildout Boxelder staff supplied 2015, 2016 and a portion of 2017 data for the wastewater treatment plant. Current Average Annual loading is 3,394 lbs./day and the maximum monthly loading is 5,231 lbs./day. Using a 2016 population of 18,282 persons (6,094 SFEs), the unit loading is 0.19 lbs. per person per day for AAL and 0.29 lbs. per person per day for MML. This data was used along with the hydraulic projections noted above to estimate the BOD loading to the facility for the 20 year planning period. Estimated average annual BOD load in 2040 is 8,200 lbs./day and the maximum monthly BOD load is 12,000lbs./day. Table III 7 shows the loading projections from 2016 to UTILITY PLAN UPDATE / 13

15 Table III 7 Loading Projections Number of taps with 3.5% Population Equivalent at 3.0 per/tap AAL Loading lbday/per@3.5% growth Max Month = Ave day x ,094 18,282 3,394 5, ,307 18,922 3,513 5, ,528 19,584 3,636 5, ,757 20,270 3,763 5, ,993 20,979 3,895 6, ,238 21,713 4,031 6, ,491 22,473 4,172 6, ,753 23,260 4,318 6, ,025 24,074 4,469 6, ,305 24,916 4,626 7, ,596 25,789 4,788 7, ,897 26,691 4,955 7, ,208 27,625 5,129 7, ,531 28,592 5,308 8, ,864 29,593 5,494 8, ,210 30,629 5,686 8, ,567 31,701 5,885 9, ,937 32,810 6,091 9, ,320 33,959 6,304 9, ,716 35,147 6,525 10, ,126 36,377 6,753 10, ,550 37,651 6,990 10, ,989 38,968 7,234 11, ,444 40,332 7,488 11, ,915 41,744 7,750 11,944 Table III 8 Estimate of Maximum Loading Estimate of Maximum Organic Loading of Wastewater Treatment Plant at System Buildout 8,200lbs. BOD/day Annual Average Load (AAL) 12,000lbs. BOD/day Maximum Month Load (MML) Figure III 5 shows the projected loading and the existing and future plant capacity. UTILITY PLAN UPDATE / 14

16 Figure III 5 Future Loading and Existing Plant Capacity UTILITY PLAN UPDATE / 15

17 Replace Section VI Wastewater System Planning Selected Plan with the following: THE SELECTED PLAN PRELIMINARY PROCESS SIZING Table V 4 Boxelder Sanitation District New Wastewater Treatment Plant Combined Plants Design Condition Summary PARAMETER DESIGN VALUES Max Monthly Flow 6.0 MGD Peak Hour Flowrate 6,662 GPM (9.6 MGD) Organic Load 12,000 lbs/day (240 mg/l) Ammonia Load 1,550 lbs/day (31 mg/l) ph Range Table V 5 Plant Expansion Preliminary Design Criteria Grit Classifier and Separator (TBD) Screenings Compactor (TBD) Flow Measurement New Influent Pump Station Influent Pumps New Kruger Ditch Type Aeration Basin Basin Type Number Capacity Discharge Disposal Type Number Capacity Type Capacity Cyclone with Screw Type Dewatering Classifier 1 (plus 1 future) 500 gpm Grit Slurry of wet screenings Ground level dumpster Landfill Spiral Press 1 (plus 1 future) 50ft 3 /hr of wet screenings (each) Parshall Flume discharge to barscreen room 24.0 MGD Influent (ultimate plant capacity Type Centrifugal VFD Number 3 Capacity 3,330 gpm (Each) Horsepower 70 HP Firm Capacity 9.6 MGD (with one pump out of service) Max. Pumping Capacity 14.4 MGD All Pumps Type Continuous Ditch Number of Basins 2 Total Volume 3.3 MG Water Depth 17 Feet UTILITY PLAN UPDATE / 16

18 Detention Design 19.8 Design BOD Loading 18.1 lbs/1000 ft3 Aerator Drive Units Type Number installed Normal Operating HP Horizontal Brush Aeration 4 60 Hp 180 HP New Final Clarifiers Final Clarifiers Return Waste and Sludge Pumps Return Activated Sludge Waste Activated Sludge Aerobic Digester Digesters Number 2 Diameter 70 Feet Depth (swd) 14 Feet Detention Ave Q. 4.8 Hrs Surface Loading 520 gpd/sf (@ Peak Month Flow) Surface Loading Peak Hr. 780 gpd/sf (@ Peak Hr Flow) Weir Loading 13,636 gpd/lf (@ Peak Flow) Solids Loading Ave. 26 lbs/day/ft2 Solids Loading Peak 39 lbs/day/ft2 Type Horizontal Centrifugal VFD Number 3 Capacity 2,600 GPM Each Recycle Range.4 to 1.25 Q infl Type Rotary Lobe Positive Displacement Number 2 Capacity 150 GPM Each Type Number Total Volume Total Volume Stabilization Criteria design Solids Detention Time Aerobic Diffused Aeration Four tanks 651,650 Gallons Each 2,600,000 Gallons >60 Days at 15 C 43,165 Gal WAS/Day (@3% thickened solids concentration) 60 days Aerators Type Blowers Type Horsepower Aeration Input Diffused Medium Bubble 5 (4 in service plus 1 standby) Positive Displacement 150 HP 30 cfm/1000 cf New UV Disinfection Facilities Ultra Violet System Type Open Channel, Low Pressure High Output Total Lamps 16 Dose 30,000 SEC/cm2 Effluent Flow metering 20 Magnetic Peak Capacity 89.0 MGD UTILITY PLAN UPDATE / 17

19 The proposed improvements are shown on Exhibit V 1. Exhibit V 1 Plant Expansion Site Plan UTILITY PLAN UPDATE / 18

20 Replace Chapter VII Management and Financial Plans with the following: VII. MANAGEMENT AND FINANCIAL PLANS Management Structure and Implementation Plan General. The Boxelder Sanitation District is a public entity under Colorado Statutes which provides wastewater services and charges users of the facilities for those services. The District is the management agency for operation of the collection system and wastewater treatment facility. The District is composed of a five member board with a District Manager and staff which includes administrative, engineering, construction inspection, and operations personnel. The operators are certified and licensed to operate the collection system and treatment facility. The District employs operators and maintenance staff or operation of its treatment facility. The current operators are licensed and sufficiently certified to operate and maintain the proposed facility. Implementation Plan. The District intends to pursue implementation of the treatment system improvements discussed in the previous chapter in order to maintain adequate service to its customers and keep the District facilities in compliance with applicable State regulations. The anticipated schedule for implementation is provided in the following table: Table VII 1 Intended Implementation Schedule Start Date Completion Date Utility Planning Phase 10/2017 3/2018 Site Application 2/2018 7/2018 Design/PDR* 2/ /2018 CMaR Contractor Selection 5/2018 7/2018 CDPHE SRF Loan Application 6/2018 Construction* 1/2019 8/2020 (19 months) Plant Start Up 9/2020 Funding. The District has requested a loan from the State Revolving Loan Fund Program administered by CDPHE. As part to that process a public meeting is required to discuss the proposed modifications to the plant. The meeting will be held and a formal public hearing with a published 30 day notice. Project costs, environmental impacts, timing, and effect on user fees will be discussed at the public hearing. UTILITY PLAN UPDATE / 19

21 Preliminary Financial Management Plan User Charge Rate Structure. To fund construction of the new wastewater treatment system, the District plans to borrow roughly $32, 000,000 (at a rate of 2.3%) payable over the 30 year planning period. The annual cost of new debt retirement is estimated to be then $1,100,000. To cover this obligation, the District will use plant investment fees and user charges. The District expects to gradually increase rate over the next 25 years at an average rate of 3% per year to match increase inflation based operating and non operating expenses. The current base residential user rate is $55.00 per month. Plant Investment Fees (PIF s). The PIF fees are paid per tap by new customers as a means of buying capacity in the plant. The monies are then used to eventually expand the system to be able to continue to provide additional capacity for new customers. It is therefore exceedingly important that the PIF be set at a proper level that will allow sufficient funds to accrue. Presently, tap fees are set at $ 12,000 per tap for all areas within the District. The District assumes gradually increasing plant investment fees over time to account to future Capital Improvement Projects and system rehabilitation. Using current budget numbers coupled with the growth projections, future values can be estimated for Year End Cash Flow balance of all funds as shown in Table VII 3 on the following page. UTILITY PLAN UPDATE / 20

22 Boxelder Sanitation District WWTP Funding Analysis 20 Year Loan Capitilization 1/26/2018 Table VII-3 Cash Flow Projection Boxelder WWTP Improvement Construction Design Phase Services $ 1,500,000 Construction Phase Services $ 1,500,000 Construction $ 27,500,000 Contingency $ 4,125,000 Total Project Cost $ 34,625,000 Annual Payment ( 30 years, 2.25% interest) $1,666, Operating Revenue Increase Non Operation Revenue Increase Operating Expenditure Increase CIP Inflation 3% 3% 3% 3% 3% 3% 4% 4% 4% 3% 3% 3% 0% 3% 0% 3% 0% 3% 0% 3% 0% 3% 3% 3% 3% 3% 3% 3% 4% 3% 4% 3% 3% 3% 0% 3% 0% 3% 0% 3% 0% 3% 0% 3% 3% 3% 3% 2% 2% 2% 2% 2% 2% 2% 2% 3% 0% 3% 0% 3% 0% 3% 0% 3% 0% 3% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% Audited Estimated Proposed Proposed Revenue Operating Revenue $ 3,479,954 $ 4,494,192 $ 5,838,318 $ 6,013,468 $ 6,193,872 $ 6,379,688 $ 6,571,078 $ 6,768,211 $ 6,971,257 $ 7,250,107 $ 7,540,112 $ 7,841,716 $ 8,076,968 $ 8,319,277 $ 8,568,855 $ 8,568,855 $ 8,825,921 $ 8,825,921 $ 9,090,698 $ 9,090,698 $ 9,363,419 $ 9,363,419 $ 9,644,322 $ 9,644,322 $ 9,933,651 Non Operating Revenue $ 1,607,922 $ 3,686,932 $ 2,450,000 $ 2,523,500 $ 2,599,205 $ 2,677,181 $ 2,757,497 $ 2,840,221 $ 2,925,428 $ 3,042,445 $ 3,133,719 $ 3,259,067 $ 3,356,839 $ 3,457,545 $ 3,561,271 $ 3,561,271 $ 3,668,109 $ 3,668,109 $ 3,778,152 $ 3,778,152 $ 3,891,497 $ 3,891,497 $ 4,008,242 $ 4,008,242 $ 4,128,489 Misc Revenue ( Loan Proceeds) $ 11,541,667 $ 11,541,667 $ 11,541,667 Total Revenue $ 5,087,876 $ 8,181,124 $ 8,288,318 $ 20,078,634 $ 20,334,743 $ 20,598,536 $ 9,328,575 $ 9,608,432 $ 9,896,685 $ 10,292,553 $ 10,673,830 $ 11,100,783 $ 11,433,807 $ 11,776,821 $ 12,130,126 $ 12,130,126 $ 12,494,030 $ 12,494,030 $ 12,868,850 $ 12,868,850 $ 13,254,916 $ 13,254,916 $ 13,652,563 $ 13,652,563 $ 14,062,140 Expenditures Operating Expenditures $ 2,519,258 $ 2,579,962 $ 3,672,445 $ 3,782,618 $ 3,896,097 $ 4,012,980 $ 4,093,239 $ 4,175,104 $ 4,258,606 $ 4,343,778 $ 4,430,654 $ 4,519,267 $ 4,609,652 $ 4,701,845 $ 4,842,901 $ 4,842,901 $ 4,988,188 $ 4,988,188 $ 5,137,833 $ 5,137,833 $ 5,291,968 $ 5,291,968 $ 5,450,728 $ 5,450,728 $ 5,614,249 Capital Outlay WWTP $ 1,079,575 $ 1,210,400 $ 11,541,667 $ 11,541,667 $ 11,541,667 Other Projects $ 1,862,903 $ 2,478,092 $ 5,498,325 $ 3,478,000 $ 3,547,560 $ 3,618,511 $ 3,690,881 $ 3,764,699 $ 3,839,993 $ 3,916,793 $ 3,995,129 $ 4,075,031 $ 4,156,532 $ 4,239,663 $ 4,324,456 $ 4,410,945 $ 4,499,164 $ 4,589,147 $ 4,680,930 $ 4,774,549 $ 4,870,040 $ 4,967,440 $ 5,066,789 $ 5,168,125 $ 5,271,488 Total Capital Outlay $ 1,862,903 $ 3,557,667 $ 6,708,725 $ 15,019,667 $ 15,089,227 $ 15,160,178 $ 3,690,881 $ 3,764,699 $ 3,839,993 $ 3,916,793 $ 3,995,129 $ 4,075,031 $ 4,156,532 $ 4,239,663 $ 4,324,456 $ 4,410,945 $ 4,499,164 $ 4,589,147 $ 4,680,930 $ 4,774,549 $ 4,870,040 $ 4,967,440 $ 5,066,789 $ 5,168,125 $ 5,271,488 Debt Service Existing Debt $ 667,928 $ 688,528 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 690,391 New Plant Debt $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 Total Debt Service $ 667,928 $ 688,528 $ 690,391 $ 690,391 $ 690,391 $ 690,391 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 2,357,113 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 $ 1,666,722 Misc Expenditures $ 1,250,000 Total Expenditures $ 6,300,089 $ 6,826,157 $ 11,071,561 $ 19,492,676 $ 19,675,715 $ 19,863,549 $ 10,141,234 $ 10,296,916 $ 10,455,712 $ 10,617,684 $ 10,782,896 $ 10,951,411 $ 11,123,297 $ 11,298,621 $ 11,524,470 $ 10,920,568 $ 11,154,074 $ 11,244,057 $ 11,485,486 $ 11,579,104 $ 11,828,730 $ 11,926,131 $ 12,184,239 $ 12,285,575 $ 12,552,459 Net Income $ (1,212,213) $ 1,354,967 $ (2,783,243) $ 585,958 $ 659,028 $ 734,987 $ (812,659) $ (688,484) $ (559,027) $ (325,132) $ (109,066) $ 149,372 $ 310,510 $ 478,200 $ 605,656 $ 1,209,558 $ 1,339,956 $ 1,249,973 $ 1,383,365 $ 1,289,746 $ 1,426,186 $ 1,328,785 $ 1,468,325 $ 1,366,989 $ 1,509,681 Beginning Fund Balance $ 9,261,620 $ 8,049,407 $ 9,404,374 $ 6,621,131 $ 7,207,089 $ 7,866,117 $ 8,601,104 $ 7,788,445 $ 7,099,961 $ 6,540,934 $ 6,215,802 $ 6,106,736 $ 6,256,108 $ 6,566,618 $ 7,044,818 $ 7,650,474 $ 8,860,032 $ 10,199,988 $ 11,449,960 $ 12,833,325 $ 14,123,072 $ 15,549,257 $ 16,878,042 $ 18,346,367 $ 19,713,356 Ending Fund Balance $ 8,049,407 $ 9,404,374 $ 6,621,131 $ 7,207,089 $ 7,866,117 $ 8,601,104 $ 7,788,445 $ 7,099,961 $ 6,540,934 $ 6,215,802 $ 6,106,736 $ 6,256,108 $ 6,566,618 $ 7,044,818 $ 7,650,474 $ 8,860,032 $ 10,199,988 $ 11,449,960 $ 12,833,325 $ 14,123,072 $ 15,549,257 $ 16,878,042 $ 18,346,367 $ 19,713,356 $ 21,223,037

23 Appendix I Monthly Data and Preliminary Effluent Limits UTILITY PLAN UPDATE / 21

24 Figure 1A 2015 Monthly Data MONTH 2015 DATA Daily Daily Daily fluent Flow, MG ph Temp 2 x Week Weekly Weekly Influent Parameters BOD 7 Day Avg BOD, lbs 7 Day Avg TSS TSS, lbs Ammonia lbs TPO4 Jan 15 Feb 15 Mar 15 Apr 15 May 15 Jun 15 Jul 15 Aug 15 Sep 15 Oct 15 Nov 15 Dec 15 MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG ANNUAL CALCS. Based on 2.34 MGD and 4,200 Lbs./Day BOD Daily Daily Daily uent Flow, M ph Temp BOD 2 x Week Influent Parameters 7 Day Avg BOD, lbs 7 Day Avg Weekly TSS TSS, lbs Ammonia Weekly lbs MAXIMUM MINIMUM AVERAGE UTILITY PLAN UPDATE / 22

25 Figure 1B 2016 Monthly Data MONTH 2016 DATA Daily Daily Daily fluent Flow, MG ph Temp 2 x Week Weekly Weekly Influent Parameters BOD BOD, lbs TSS TSS, lbs Ammonia lbs TPO4 TPO4, Lbs January February March April May June July August September October November Decembe r MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG ANNUAL CALCS. Based on 2.34 MGD and 4,200 Lbs./Day BOD MAXIMUM MINIMUM AVERAGE Daily Influent Flow, MGD Daily Daily 2 x Week Weekly Influent Parameters ph Temp BOD BOD, lbs TSS TSS, lbs Ammonia Weekly lbs TPO4 TPO4, Lbs UTILITY PLAN UPDATE / 23

26 Figure 1C 2017 Monthly Data 2017 Annual Data Influent Flow, MGD MGD ph Temp BOD BOD, lbs TSS TSS, lbs Ammonia NH3, lbs TPO4 TPO4, lbs January February March April MAY JUNE July August September October November December Annual Calcs MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG MAX MIN AVG #DIV/0! #DIV/0! MAX MIN AVG #DIV/0! #DIV/0! MAX MIN AVG #DIV/0! #DIV/0! MAX MIN AVG MAX MIN AVG #DIV/0! #DIV/0! MAX MIN AVG #DIV/0! #DIV/0! MAX #DIV/0! #DIV/0! MIN #DIV/0! #DIV/0! AVG #DIV/0! #DIV/0! MAX #DIV/0! #DIV/0! MIN #DIV/0! #DIV/0! AVG #DIV/0! #DIV/0! UTILITY PLAN UPDATE / 24

27 Karen Reynolds Boxelder Sanitation District P.O. Box 1518 Ft. Collins, CO TO: FROM: Karen Reynolds, District Manager Permit Writer: Andrea Stucky, , Reviewed by: Kelly Drengler, , DATE: August 3, 2017 Re: PEL200521, Boxelder Sanitation District WWTF Preliminary Effluent Limit The Water Quality Control Division (Division) of the Colorado Department of Public Health and Environment has prepared, per your request, the Preliminary Effluent Limits (PELs) for the rehabilitation and expansion of the Boxelder Sanitation District wastewater treatment facility (WWTF). These effluent limits were developed as detailed in the attached document, for use as one of the submittals in your application for Site Approval. With a hydraulic design capacity of 6.0 million gallons per day (MGD) and discharge into Boxelder Creek which then flows into the Cache La Poudre River, which is identified as stream segments COSPCP13b (Boxelder Creek) and COSPCP12 (Cache La Poudre) the Boxelder WWTF will require an individual permit. PELs developed for this facility are based on the water quality standards for the receiving stream identified in the PEL application, and/or on technology based limitations established in the Regulations for Effluent Limitations (Regulation No. 62) The water quality standard based limitations presented in this PEL may be incorporated into a CDPS permit contingent on analyses conducted during permit development. The technology based limitations will also be incorporated into the permit unless a more stringent limitation is applied. As explained in the attached document, these limitations have been developed based on the current and/or next effective water quality standards for the receiving stream, the ambient water quality of the receiving stream, the calculated low flows, the stated design flow of the facility, technology based limitations established in the Regulations for Effluent Limitations (Regulation No. 62), applicable federal Effluent Limitation Guidelines (ELGs), and where necessary the antidegradation regulations, mixing zone policies, and any designation of a receiving stream by the US Fish and Wildlife Service as habitat for federally listed threatened and endangered (T&E) fish. A determination of which PELs ultimately apply in a permit will be dependent on decisions made by the permittee regarding treatment facilities, discharge type, industrial contributions, receiving streams, design flows, or other information presented to the Division at the time of permit application. Table 1 contains a summary of the limitations that have been developed in this PEL, for which the proposed treatment facility will be evaluated against, under the Site Approval Process. This evaluation will include a determination of whether the proposed treatment facility as designed, Appendix A Preliminary Effluent Limits Page 1 of Cherry Creek Drive S., Denver, CO P

28 can meet these limitations. A new wastewater treatment facility will be expected to meet the limitations for these parameters upon commencement of discharge. Table 2 contains a summary of the limitations that have been developed in this PEL, for which the proposed treatment facility may or may not be evaluated against, under the Site Approval Process. The limitations contained in this table may be able to be met by the development of a pretreatment program, the refinement of local limits under an existing pretreatment program, or other methods of source water control. In these instances, the ability of the facility to meet these limitations will not be reviewed under the Site Approval process and are the responsibility of the permittee. If treatment or other operational control method is to be used specific to a parameter(s) in this table, the ability of the facility to meet the limitation(s) will be reviewed under the Site Approval process. A new wastewater treatment facility will be expected to meet the limitations for these parameters upon commencement of discharge. Table 1 Preliminary Effluent Limits for Evaluation under the Site Approval Process Discharge to Boxelder Creek/Cache La Poudre River at a Design Flow of 6.0 MGD BOD 5 (mg/l) 45 (7-day average), 30 (30-day average) BOD 5 (% removal) TSS, mechanical plant (mg/l) TSS, mechanical plant (% removal) Oil and Grease (mg/l) ph (s.u.) 85 (30-day average) 45 (7-day average), 30 (30-day average) 85 (30-day average) 10 (maximum) (minimum-maximum) Other Pollutants Max. Limits or WQBELs NILs Temp DM and Temp MWAT ( C) Report (daily maximum) March-Nov Report (MWAT) NA Temp DM and Temp MWAT ( C) Report (daily maximum) Dec-Feb Report (MWAT) NA E. coli (#/100 ml) 252 (7-day geomean) May-Oct 346 (7-day geomean) Nov-Apr 115 (30-day geomean) TRC (mg/l) (daily maximum) (30-day average) Total Inorganic Nitrogen as N (mg/l) 10 (daily maximum) NA Total Ammonia WQBELs NILs NH3 as N, Tot (mg/l) Jan 13 (daily maximum) 3.4 (30-day average) NH3 as N, Tot (mg/l) Feb 11 (daily maximum) 3.3 (30-day average) NH3 as N, Tot (mg/l) Mar 12 (daily maximum) 3.4 (30-day average) NH3 as N, Tot (mg/l) Apr 12 (daily maximum) 2.3 (30-day average) NH3 as N, Tot (mg/l) May 17 (daily maximum) 2.7 (30-day average) NH3 as N, Tot (mg/l) Jun 32 (daily maximum) 3.2 (30-day average) NH3 as N, Tot (mg/l) Jul 12 (daily maximum) 2.8 (30-day average) NH3 as N, Tot (mg/l) Aug 12 (daily maximum) 2.9 (30-day average) NH3 as N, Tot (mg/l) Sep 12 (daily maximum) 2.6 (30-day average) NH3 as N, Tot (mg/l) Oct 18 (daily maximum) 3.0 (30-day average) Appendix A Preliminary Effluent Limits Page 2 of Cherry Creek Drive S., Denver, CO P

29 NH3 as N, Tot (mg/l) Nov 6.8 (daily maximum) 3.4 (30-day average) NH3 as N, Tot (mg/l) Dec 13 (daily maximum) 3.9 (30-day average) Table 2 Preliminary Effluent Limits for Evaluation by the Permittee Discharge to Boxelder Creek/Cache La Poudre River at a Design Flow of 6.0 MGD Metals and Cyanide WQBELs NILs As, TR (µg/l) 12 (30-day average) NA As, Dis (µg/l) 424 (daily maximum) NA Cd, Dis (µg/l) 11 (daily maximum) 1.6 (30-day average) NA Cr+3, TR (µg/l) 137 (30-day average) NA Cr+3, Dis (µg/l) 2211 (daily maximum), 314 (30-day average) NA Cr+6, Dis (µg/l) 20 (daily maximum) 8.3 (30-day average) Cu, Dis (µg/l) 62 (daily maximum) 22 (30-day average) CN, Free (µg/l) 6.2 (daily maximum) NA Fe, Dis (µg/l) WS* 408 (30-day average) NA Fe, TR (µg/l) 1318 (30-day average) NA Pb, Dis (µg/l) 15 (daily maximum) 8.2 (30-day average) Mn, Dis (µg/l) WS* 5905 (daily maximum), 62 (30-day average) Mo, TR (µg/l) 205 (30-day average) NA Hg, Tot (µg/l) NA (30-day average) Ni, Dis (µg/l) 1887 (daily maximum) 126 (30-day average) Se, Dis (µg/l) 20 (daily maximum) 2.5 (30-day average) Ag, Dis (µg/l) 27 (daily maximum) 2.6 (30-day average) Zn, Dis (µg/l) 702 (daily maximum) 240 (30-day average) Sulfate (mg/l) WS* 340 (30-day average) NA *Water Supply Parameters NA Appendix A Preliminary Effluent Limits Page 3 of Cherry Creek Drive S., Denver, CO P