2013 PRELIMINARY ENGINEERING REPORT.pdf

PRELIMINARY ENGINEERING REPORT

To support the

Colorado Department of Public Health and Environment Site Application Amendment and Water Pollution Control Revolving Fund Loan Application for the

LYONS WASTEWATER TREATMENT PLANT

UPGRADE PROJECT

Submitted by:

Honeywell Building Solutions and

Tetra Tech Inc.

On behalf of

The Town of Lyons, Colorado

April 20, 2013

Lyons WWTP Upgrade Preliminary Engineering Report ii

TABLE OF CONTENTS

TABLE OF CONTENTS ......................................................................................................... ii

Figures ....................................................................................................................................... iv

Tables ......................................................................................................................................... v

Appendices ................................................................................................................................ vi

Abbreviations .......................................................................................................................... vii

SECTION 1

Introduction

1.1. Project Overview

1.2. Permit Limits

SECTION 2................................................................................................................................. 2-1

Planning Conditions ................................................................................................................. 2-1

2.1. Planning Area........................................................................................................... 2-1

2.2. Plan Coordination .................................................................................................... 2-1

2.3. Growth ..................................................................................................................... 2-2

2.4. Wastewater Flow Forecasts ..................................................................................... 2-2

2.5. Wastewater Load Forecasts ..................................................................................... 2-4

SECTION 3................................................................................................................................. 3-1

Existing Facilities ..................................................................................................................... 3-1

3.1. Service Area Features .............................................................................................. 3-1

3.2. Area Discharge Permits ........................................................................................... 3-2

3.3. Existing Facility Description ................................................................................... 3-3

3.4. Wastewater Flow and Load Analysis ...................................................................... 3-6

3.5. Financial Status ........................................................................................................ 3-7

SECTION 4................................................................................................................................. 4-1

Project Purpose and Need ........................................................................................................ 4-1

4.1. Compliance History ................................................................................................. 4-1

4.2. Security .................................................................................................................... 4-2

4.3. Operation and Maintenance ..................................................................................... 4-3

4.4. Growth and Capacity ............................................................................................... 4-3

SECTION 5................................................................................................................................. 5-1

Alternatives Analysis ............................................................................................................... 5-1

Lyons WWTP Upgrade Preliminary Engineering Report iii

5.1. Alternative 1 – Upgrade Existing Facilities ............................................................. 5-6

5.2. Alternative 2 – SBR at New Site ........................................................................... 5-16

5.3. Alternative 3 – Regionalization, Connection to Longmont ................................... 5-18

5.4. Non-Economic Evaluation ..................................................................................... 5-20

5.5. Combined Ranking ................................................................................................ 5-23

SECTION 6................................................................................................................................. 6-1

Selected Alternative ............................................................................................................... 6-1

6.1. Justification of Selected Alternative ........................................................................ 6-1

6.2. Technical Description .............................................................................................. 6-1

6.3. Environmental Review of Selected Alternative ....................................................... 6-4

6.4. Green Project Reserve .............................................................................................. 6-4

6.5. Cost Summary .......................................................................................................... 6-4

6.6. Project Implementation Schedule ............................................................................ 6-5

SECTION 7................................................................................................................................. 7-1

FIGURES ................................................................................................................................ 7-1 Figure 2-1 Lyons Planning Area Map ........................................................................... 7-1 Figure 2-2 Floodplain Map ............................................................................................ 7-1 Figure 3-1 Existing Layout and Aerial .......................................................................... 7-1 Figure 3-2 Plant Influent Flow and Load ...................................................................... 7-1 Figure 5-1 Alternative 1a Partial SBR Upgrade Process Flow Diagram ....................... 7-1 Figure 5-2 Alternative 1b Full SBR Upgrade Process Flow Diagram .......................... 7-1 Figure 5-3 Alternative 1b Proposed Site Layout ........................................................... 7-1 Figure 5-4 Alternative 1c Full MBR Upgrade Process Flow Diagram ......................... 7-1

SECTION 8................................................................................................................................. 8-1

APPENDICES ........................................................................................................................ 8-1 Appendix A JVA Report – Provided under separate cover ............................................. 8-1 Appendix B Honeywell Report – Provided under separate cover ................................... 8-1 Appendix C Area Maps – See following pages ............................................................... 8-1 Appendix D MWE Report – Provided under separate cover ........................................... 8-1

Lyons WWTP Upgrade Preliminary Engineering Report iv

Figures

Figure 2-1 Lyons Planning Area Map

Figure 2-2 Floodplain Map

Figure 3-1 Existing Layout and Aerial

Figure 3-2 Plant Influent Flow and Load

Figure 5-1 Alternative 1a Partial SBR Upgrade Process Flow Diagram

Figure 5-2 Alternative 1b Full SBR Upgrade Process Flow Diagram

Figure 5-3 Alternative 1b Proposed Site Layout

Figure 5-4 Alternative 1c Full MBR Upgrade Process Flow Diagram

Lyons WWTP Upgrade Preliminary Engineering Report v

Tables

Table 1-1 Effluent Limits for CDPS CO-0020877

Table 2-1 Historic and Projected Wastewater Flows

Table 2-2 Historic and Projected Annual Average Wastewater Loads

Table 3-1 Area Discharge Permits

Table 3-2 Overview of Existing Facilities

Table 3-3 Rate Structure

Table 5-1 SBR Operational Steps

Table 5-2 Alternative 1a Design Criteria

Table 5-3 Alternative 1b Design Criteria

Table 5-4 Alternative 1c Design Criteria

Table 5-5 Non-Monetary Ranking

Table 5-6 Life Cycle Costs

Table 5-7 Combined Monetary and Non-monetary Decision Matrix

Table 6-1 Proposed Preliminary Treatment System

Table 6-2 Proposed Secondary Treatment System

Table 6-3 Proposed Solids Handling

Table 6-4 Anticipated Project Schedule

Lyons WWTP Upgrade Preliminary Engineering Report vi

Appendices

Appendix A JVA Report Wastewater Feasibility Study for the Town of Lyons

Appendix B Honeywell Report

Level 1 Conceptual Analysis and Engineer’s Opinion of Probable Cost for Upgrade or Replacement of the Town of Lyon’s Wastewater Treatment Plant

Appendix C Area Maps Soils Map National Wetlands Inventory Map

Appendix D McLaughlin Water Engineers (“MWE”) Report Lyons Wastewater Treatment Plant Site Floodplain Narrative Report

Lyons WWTP Upgrade Preliminary Engineering Report vii

Abbreviations

AA Annual Average AAF Annual Average Flow AIWPS Advanced Integrated Wastewater Pond System AOR Actual Oxygen Required BOD/BOD5 Biochemical Oxygen Demand CDPHE Colorado Department of Public Health and Environment CDPS Colorado Discharge Permit System CLOMR Conditional Letter of Map Revision °C Degrees Celsius DMR Discharge Monthly Report DRCOG Denver Regional Council of Governments ECHO Enforcement and Compliance History Online EPA Environmental Protection Agency EQ Equalization EQR Equivalent Residential ESCO Energy Services Company FEMA Federal Emergency Management Agency FOG fats, oil and grease F:M Food to Microorganism Ratio ft feet °F Degrees Fahrenheit gpcd gallons per capita per day gpd/EQR gallons of sewage per day per EQR gpm gallons per minute Hp Horsepower HRT Hydraulic Retention Time IFAS Integrated Fixed Film Activated Sludge I&I Infiltration and Inflow IS Individual Score lbs pounds LOMR Letter of Map Revision µg/L Micrograms per Liter MG Million Gallons MGD Million Gallons per Day

Lyons WWTP Upgrade Preliminary Engineering Report viii mg/L Milligrams per Liter MBR Membrane Bioreactor MLSS Mixed Liquor Suspended Solids MM Maximum Month MMBR Moving Bed Bioreactor MWAT Maximum Weekly Average Temperature MWE McLaughlin Water Engineers LTD NH3 Ammonia O&M Operation and Maintenance OPC Opinion of probable costs PEL Preliminary Effluent Limit PDR Process Design Report PER Preliminary Engineering Report PLC Programmable Logic Controller ppcd pounds per capita per day RDT Rotary Drum Thickener SBR Sequencing Batch Reactors SCADA Supervisory Control and Data Acquisition SNC/HPV Significant Non-compliance/High Priority Violation SRT Solids Retention Time TDH Total Dynamic Head TF/SC Trickling Filter/Solids Contact TIN Total Inorganic Nitrogen TMDL Total Maximum Daily Load TN Total Nitrogen TP Total Phosphorus TSS Total Suspended Solids UV Ultraviolet VFD Variable Frequency Drive WPCRF Water Pollution Control Revolving Fund WQCD Water Quality Control Division WS Weighted Score WWTP Wastewater Treatment Plant

Lyons WWTP Upgrade Preliminary Engineering Report 1-1

SECTION 1

Introduction The Town of Lyons, Colorado (“Town” or “Lyons”) owns a wastewater treatment plant (WWTP) that lacks unit process redundancy and is reaching the end of its useful life.

Many of the components in the plant have reached the end of their useful life and are in need of being replaced. There are a number of other issues that are described in section

1.1 below.

The Town has entered into an energy performance contracting (“EPC”) process with Honeywell Building Solutions (Honeywell), a Colorado Energy Office approved Energy Services Company (ESCo). The EPC process is designed around a turnkey design-build effort by Honeywell, wherein Honeywell is responsible for assessing current conditions, developing a comprehensive plan to address these issues, implementing the plan and guaranteeing post-renovation technical, operational and cost savings performance.

Honeywell has retained the services of Tetra Tech, Inc. as a sub-consultant to assist with pre-construction engineering and loan application activities.

As part of the financing package for this project, the Town will apply for a Water Pollution Control Revolving Fund (WPCRF) loan. This Preliminary Engineering Report (PER) has been developed in accordance with guidance from the Colorado Department of Public Health and Environment (CDPHE) to help the Town qualify for a WPCRF loan and provide the information necessary for approval of a site application amendment, which is a necessary CDPHE approval step regardless of funding approach.

Prior to the completion of this PER, two engineering reports were developed for this project. The first report, which is included as Appendix A, entitled Wastewater Feasibility Study for the Town of Lyons was prepared by JVA Inc. in 2011 and will be referred to throughout the PER as the JVA Report. The second report, which is included as Appendix B, entitled Level 1 Conceptual Analysis and Engineer’s Opinion of Probable Cost for Upgrade or Replacement of the Town of Lyon’s Wastewater Treatment Plant was prepared by Honeywell and will be referred to throughout the PER as the Honeywell Report. Complete sections of these reports are referred to within the PER, where applicable.

Lyons WWTP Upgrade Preliminary Engineering Report 1-2

1.1. Project Overview

In 2011, the Town of Lyons, the Town Engineer (JLB Engineering Consultants, or JLB), various stakeholders, and Honeywell identified the need for improvements at the WWTP during an evaluation of the Town’s wastewater treatment system. Honeywell has been working with the Town since 2009 evaluating the current situation and providing improvement recommendations. In 2010, Honeywell executed a “Technical Energy Audit Contract” with the Town under the Colorado Energy Office’s energy performance contracting program (“EPC”) to evaluate a water meter upgrade program and energy efficiency improvements at the WWTP. During this evaluation, all of the interested parties realized there were too many operational challenges at the WWTP to only implement energy efficient measures.

As noted in Section 1.1, Page 5 of the Honeywell Report, the following issues were identified in the evaluation by the Town, JLB, Honeywell, and JVA Inc.:

Risk of major plant shut-down from component failures as a result of the age and lack of redundancy/reliability of major system components (e.g.

clarifier, blowers, and controls)

Objectionable levels of noise pollution Excessive and objectionable levels of odors Floodplain compliance issues Undesirable aesthetics Higher than desired out-sourced cost of operations Higher than desired energy consumption and costs Changing CDPHE effluent parameter limits

These issues were taken into account when developing a number of alternative improvements for the existing system, which are presented in the JVA Report and the Honeywell Report.

In early 2013, Honeywell teamed with Tetra Tech for the design development and construction of the upgrades for the Lyons WWTP. Tetra Tech is assisting Honeywell with the basis of design, permitting, applying for a WPCRF loan, soliciting design-build subcontractor bids, and construction phase oversight. This PER was developed to jointly support regulatory review and approval of both a CDPHE site application amendment and the WPCRF loan. Accordingly, the PER addresses the following topics:

Planning conditions Existing facilities Project purpose and need Assessment of alternatives

Lyons WWTP Upgrade Preliminary Engineering Report 1-3

Selected alternative

1.1.1. Project Goals

The primary goals of this project are as follows:

Address critical issues with the current WWTP including age, reliability, odor, noise and excessive operating costs

Use a combination of capital reserves from the water/wastewater utility fund and a low-interest WPCRF loan to minimize ratepayer impacts.

Repay the WPCRF loan with a combination of Honeywell guaranteed operational cost savings and a sewer ratepayer increase.

Implement improvements that are “green” and sustainable in nature Demonstrate that the project meets CDPHE “green reserve” funding requirements such that a portion of the WPCRF funding package may qualify as a no interest loan

Transfer the risk for technical, operational, and financial performance to Honeywell

1.2. Permit Limits

The Town is currently operating under a Colorado Discharge Permit System (CDPS) permit number CO-0020877, which was issued in June 2009 and expires in June 2014. The current effluent limits are summarized in Table 1-1.

Table 1-1 Effluent Limits for CDPS CO-0020877

Effluent Parameter Effluent Limitation Maximum Concentrations

30-Day Average 7-Day Average Daily Maximum Effluent Flow, million gallons per day (MGD)

0.381 NA NA

pH, (Standard Unit) NA NA 6.5-9.0 E. coli, (#/100 milliliter) 583 1166 NA TRC, milligrams per liter (mg/L)

0.09 NA 0.035

Ammonia (NH3), (mg/L) Jan-Mar

8 NA NA

NH3, (mg/L) Apr-Jun 11 NA NA NH3, (mg/L) Jul-Sep 9.8 NA NA NH3, (mg/L) Oct-Dec 6 NA NA BOD5, (mg/L) 30 45 NA BOD5, percent removal 85 NA NA Total Suspended Solids (TSS), (mg/L)

30 45 NA

TSS, percent removal 85 NA NA

Lyons WWTP Upgrade Preliminary Engineering Report 1-4

Effluent Parameter Effluent Limitation Maximum Concentrations

30-Day Average 7-Day Average Daily Maximum Oil and Grease, (mg/L) NA NA 10 Copper, Potentially Dissolved, micrograms per liter (µg/L)

Report NA Report

Temperature, maximum weekly average temperature (MWAT), degrees Celsius (°C)

NA 20 NA

Note:

1. NA – not applicable

A Preliminary Effluent Limits (PELs) application was submitted to CDPHE on February 28, 2013. The PELs developed by CDPHE will be based on their current water quality regulations. The goal of the PER is to develop a recommended set of improvements that will meet permit requirements that will be in place when the new facilities come on-line, with an eye on pre-positioning to comply with discharge limitations that may be required in future permits. The PELs are a necessary step in defining the effluent quality criteria upon which the WWTP will be designed. Tetra Tech will submit the PELs once they have been obtained.

It is anticipated the effluent limits in the next permit will be very similar to those listed in Table 1-1, except for temperature. New in-stream temperature standards vary seasonally. For cold water bodies, the MWAT in the stream varies from 17°C during June to September, and 9°C from October to May. The temperature of the Lyons WWTP (as with any domestic WWTP in Colorado) will likely exceed these in-stream temperature limits. If there is sufficient dilution within the allowable effluent/stream mixing zone, the Town will not be assigned a temperature limit. If a temperature limit is included in the new PELs, the best compliance approach may be to install a diffuser in the St. Vrain to increase the degree of mixing, dilution, and temperature reduction within the allowable mixing zone. Should that come to pass, the Town will ask for a compliance schedule to conduct such studies and determine if a diffuser or effluent heat recovery is the best approach for temperature compliance.

Lyons WWTP Upgrade Preliminary Engineering Report 2-1

SECTION 2

Planning Conditions To select the most appropriate alternative for the WWTP, it is essential to have an understanding of the planning area and the wastewater characteristics. This Section discusses the planning area, coordination with regulatory entities, population growth, and forecasts of wastewater flow and loads.

2.1. Planning Area

The Town is located in Boulder County approximately 16 miles north of Boulder, Colorado. The Town is located at the intersection of State Highway 7 and U.S.

Highway 36. Figure 2.1 is the 2010 Lyons Planning Area Map used to project the alternative requirements.

As noted in Section 2, Page 8 of the JVA Report, the Lyons Planning Area is generally mountain foothills with sloped areas transitioning to flat terrain. The soils in the area are mainly Colluvial land, Pinata-Rock outcrop complex with slopes ranging from 5 to 55 percent, and Niwot sands. A soils map is included in Appendix C.

The Town is located at the confluence of the North St. Vrain Creek and the South St. Vrain Creek; therefore, portions of the Town along the creek are located in a 100-year floodplain. The Federal Emergency Management Agency (FEMA) floodplain map for the Town is included as Figure 2.2. There are no major lakes located within the town boundary; however, there are wetlands. The type of wetlands in the area consists of forested/shrub freshwater wetlands and freshwater ponds. A wetlands map for the town is included in Appendix C.

2.2. Plan Coordination

The Boulder County Land Use Planning Division and the Water Quality Control Division (WQCD) is responsible for reviewing and coordinating projects associated with the WWTP. As noted Section 1, Page 2 of the JVA Report, the Denver Regional Council of Governments (DRCOG) was the 208 Management Agency for the Town until the end of 2010, when it stopped providing this service and the responsibility for doing so fell back on CDPHE.

Lyons WWTP Upgrade Preliminary Engineering Report 2-2

The DRCOG Clean Water Plan, which was published in 1998 and amended in 2009, included the Town as a major discharger and a management agency in the St. Vrain Watershed. The plan describes “wastewater management strategies, watershed water quality programs, wasteload allocations, stream standards, priority regional projects, nonpoint sources control strategies and stormwater management programs.” The goal of the plan was “to restore and maintain the chemical and physical integrity of the region’s waters to ensure clean water for residents and a balanced, healthy ecological community.” Local governments, agencies, or organizations had the responsibility to implement the elements of the Clean Water Plan in their area.

2.3. Growth

Based on 2010 Census information, the total Town population was 2,033 individuals. Total number of housing units was counted as 904 and total occupied was 861, which gives an approximate housing equivalent of 2.361 individuals per housing unit.

According to page 3 of the JVA Report, the Town will achieve build-out by 2018 with a population of 2,535. Estimate of the build-out was based on a projected

2.8 percent growth rate, which was determined on pages 2 and 3 of the JVA Report. Table 2 on page 3 of the JVA Report presents the estimated growth for each year. Population projections are based on the planning area presented in Figure 2.1.

2.4. Wastewater Flow Forecasts

Historical influent wastewater flows, BOD5, TSS, and ammonia data were analyzed on a per-capita basis using a 2.8 percent annual linear population growth and 2010 Census information. An Equivalent Residential (EQR) unit was calculated based on population and winter water usage information from the JVA report. In 2010, there was an average winter month water usage of 3.55 million gallons (MG) by approximately 748 single family residential taps and 1.77 MG by other users, which includes both multi-family and commercial customers.

Consumptive use in the winter non-irrigation season was assumed to be 5 percent.

Based on this information, the 2010 average annual WWTP influent flow rate (0.1554 MGD) was subdivided into 0.1036 MGD of single family residential flow and 0.0518 MGD from other customers.

The 2010 Census identified 861 occupied households, which is greater than the average number of residential taps for the same year (748) meaning that 113 households could be associated with multi-family taps. Each single-family residential tap can be defined as one EQR and thus produces 0.1036 MGD/748 or

Lyons WWTP Upgrade Preliminary Engineering Report 2-3 approximately 138.5 gallons of sewage per day per EQR (gpd/EQR) on an annual average (AA) basis.

The remainder of wastewater influent flow (0.0518 MGD) is then comprised of commercial and multi-family users. Dividing this flow rate by the above-calculated 138.5 gpd/EQR, yields approximately 374 non-single-family EQRs.

For this analysis, it is assumed that single and multi-family households have similar per EQR wastewater contributions. Therefore, of the 374 non-single-family EQRs, 113 are assumed to be multi-family EQRs and the remaining 261 EQRs are commercial. The total number of EQRs comes to 1,122 and, given a 2010 Census population of 2,033, the average number of people per EQR comes to 1.812. This suggests that the annual average flow (AAF) contribution per person is about 76 gallons per capita per day (gpcd), including infiltration, which is comparable to other primarily residential communities in Colorado with reasonably tight collection systems and where many of the structures have newer water efficient fixtures. Since this value is likely to trend down further based on historic data from other communities, a value of 70 gpcd, or 127 gpd/EQR was used for making future projections.

Table 2-1 below shows an analysis of historical wastewater flows and gives projections up to build out conditions, assumed to be the year 2018.

Table 2-1 Historic and Projected Wastewater Flows

Current Data

Annual Average/ Capita (gpcd)

Maximum Month :

AA

Peak Day: AA

Annual Average/

EQR

(gpcd)

2006 - 2011 69.8 1.361 2.348 126.4

Years Annual Average

(MGD)

Peak Month est.

(MGD)

Peak Day est.

(MGD)

EQRs

2006 - 2011 0.132 0.180 0.310 1,185 2013 0.154 0.209 0.361 1,216 2014 0.158 0.215 0.370 1,248 2015 0.162 0.220 0.380 1,279 2016 0.166 0.226 0.389 1,310 2017 0.170 0.231 0.398 1,342 2018 0.174 0.236 0.408 1,373

Growth projections are based on population, not EQRs, because historical wastewater tap and/or EQR data was unavailable for analysis. Maximum month

Lyons WWTP Upgrade Preliminary Engineering Report 2-4

(MM) and peak day (PD) ratios were determined using all available flow data.

Based on this evaluation, the recommended MM:AA peaking factor is 1.36, and

2.35 for PD:AA.

Barring September 2011 data, which appeared to be an outlier, the highest recorded monthly average flow at Lyons WWTP was about 0.19 MGD, or approximately 50 percent of the 30-day average flow design capacity of the plant (0.381 MGD). At build out conditions, 30-day average flows could reach 62 percent of the plant’s current maximum month capacity rating. The highest 24-hour flow on record so far has been 0.37 MGD.

2.5. Wastewater Load Forecasts

Eight-hour composite samples are used to determine the influent and effluent BOD and TSS concentrations reported on the discharge monitoring reports (DMRs) for the Lyons WWTP. BOD information prior to 2008 varied beyond reasonable limits and was omitted, along with the top and bottom 10 percent the remaining 2008 to 2013 data. When corrected on a per-capita basis, historic annual average TSS information was often at or below the lower limits of industry-accepted values (0.13-0.30 lbs/cap/day). In addition, the data showed a high degree of variability. Therefore, a brief effort was undertaken to collect 24-hour, flow-proportional samples. However, this data was also highly variable and could not, by itself, be used to determine the organic strength of the influent wastewater.

What the historic and special sampling results seem to indicate is that the Lyons wastewater strength is stronger than textbook values, which is becoming more the norm in Colorado due to drought, lower infiltration rates, and water saving plumbing fixtures. Therefore, Tetra Tech’s best professional judgment was used to select the unit wastewater loading criteria presented in Table 2-2, which equates to 0.21 pounds per capita per day (ppcd) for BOD, and 0.20 ppcd for TSS.

A proportionate value of 0.023 ppcd was utilized for influent ammonia loads.

Lyons WWTP Upgrade Preliminary Engineering Report 2-5

Table 2-2 Historic and Projected Annual Average Wastewater Loads

Historic and Current Lab

Data (lbs/EQR/day)

BOD

load/EQR

TSS

load/EQR Ammonia load/EQR

0.38 0.36 0.042

Years BOD load TSS load NH3-N load lbs/day lbs/day lbs/day Current 463 435 49.8

2013 463 441 50.7 2014 475 452 52.0 2015 487 464 53.3 2016 499 475 54.6 2017 511 486 55.9 2018 523 498 57.2

The Lyons WWTP is rated for a maximum 30-day BOD load of 705 lbs/day. It is anticipated that the MM:AA load ratio will be less than the 1.36 value selected for flow because flow variability can be more strongly affected by such factors as rainfall, runoff, groundwater levels, and leaking sewer pipes. Therefore, a MM:AA organic load peaking of factor of 1.25 will be applied to both BOD and TSS, which is representative of other wastewater utilities along Colorado’s Front Range. As a result, the design maximum month unit contributions of BOD, TSS, and ammonia are 0.26, 0.25, and 0.029 ppcd, respectively.

Assuming a build out population of 2535 people, the ultimate maximum month BOD load is projected to be 660 ppd, which is about seven percent less than the current rated capacity of the Lyons WWTP. Ultimate maximum month flows, however, are only projected to be in the range of 0.236 MGD, or 62 percent of the current rated capacity of 0.381 MGD. Therefore, the Lyons WWTP is much more limited by organic load than flow. Accordingly, the Town Board must keep close tabs on organic load trends and not just focus on flow. As a precaution against higher than expected future loads, the design will be configured such that the organic load capacity can be cost-effectively increased in the future by increasing the mixed liquor concentration and aeration capacities, without the need for significant capital improvements.

A word of caution, however, is that the Lyons WWTP is a small domestic waste treatment plant and a single commercial/industrial customer with a continuous or intermittent concentrated waste stream could overwhelm the organic load treatment capacity of the plant. This plant will not be able to accept septage or food wastes such as fats, oils, and grease (FOG). The Town must be vigilant to

Lyons WWTP Upgrade Preliminary Engineering Report 2-6 ensure such high strength wastes go to a larger community and/or facility more capable of handling them.

Lyons WWTP Upgrade Preliminary Engineering Report 3-1

SECTION 3

Existing Facilities The current facilities at the Lyons WWTP were mainly constructed in 1976; however, there were existing facilities at the WWTP location years before the existing system.

Prior to the addition of the sludge lagoon in 1969, the plant consisted of a lift station, clarifier, digester, and control building. All of these units, including the sludge lagoon, have been decommissioned. The sludge lagoon is currently set aside as an emergency storage pond in the case of a plant upset or major equipment failure. This section will discuss the existing facilities, in addition to the service area, area discharges, wastewater flow and load analysis, and the Town’s financial status.

3.1. Service Area Features

In addition to the Lyons WWTP, the Town maintains and operates three pumping stations in the planning area. Figure 2.1 shows the approximate locations of these pumping stations. In addition to these pumping stations, there is an additional pumping station, the Riverbend Lift Station, which is privately owned and operated. There are no additional municipal and industrial treatment plants, sludge management areas and facilities, pretreatment plants, and any significantly developed areas serviced by onsite or unconventional systems in the service area.

3.1.1. Floodplain

As noted in Section 2.1, portions of the Town along the St. Vrain Creek are located in a 100-year floodplain. Figure 2.2 shows the Lyons WWTP located in the floodway. FEMA defines the floodway as “the channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the one percent annual chance flood can be carried without substantial increases in flood heights.”

Section 3, page 8 of the JVA Report includes a discussion of the floodplain and notes that the Town perform a survey and hydraulic model to verify flood data.

The report also notes that if improvements occur at the existing WWTP site, a Conditional Letter of Map Revision (CLOMR) and a Letter of Map Revision (LOMR) from FEMA is going to be required.

In April 2012, McLaughlin Water Engineers LTD (MWE) developed the Lyons Wastewater Treatment Plant Site Floodplain Narrative Report, which is included

Lyons WWTP Upgrade Preliminary Engineering Report 3-2 as Appendix D and will be referred to throughout the PER as the MWE Report.

The purpose of the study was to determine if it is feasible to construct improvements at the existing site. An updated floodplain survey, Drawing 1 in the MWE Report, shows that most of the existing facilities at the WWTP are located on an “island” out of the floodway. However, the “island” is not shown on the current FEMA map. According to the study, MWE recommended that the previous model be revisited with FEMA to recognize these conditions. In addition, the study identified that implementing of a number of mitigation measures, such as adding a berm and box culverts, can eliminate the property from being in a floodway/floodplain and avoid adverse impacts to adjacent properties. However, a more in-depth hydraulic analysis is required.

The recommended near-term improvements can fit on the island identified in the MWE Report, which will be shown in Section 5.0. The Town has not yet decided if it will seek a LOMR to have FEMA recognize the island identified by MWE, or implement some hydraulic improvements in and around the 2nd Street Bridge, which would shift the 100-year floodway back toward the current creek alignment and create more usable/buildable area at the WWTP. The Town recognizes that it must select one of these two options and move forward with the FEMA approval process before CDPHE can give final consent to the PER and a WPCRF loan for Lyons.

3.2. Area Discharge Permits

As noted on page 17 of the JVA Report, the Lyons WWTP discharges into the St.

Vrain Creek, Stream Segment COSPSV02b_0800. No other municipal facilities discharge into this stream segment; however, there are three industrial dischargers that are within a five mile radius of the WWTP that discharge into the stream.

Table 3.1 presents the facility and facility information.

Table 3-1 Area Discharge Permits

Facility NPDES ID Permit Type Primary Industry

Classification Aggregate Industries

WCR Inc.

COG500077

Minor Permit

General Permit Covered Facility

Construction Sand and Gravel

Cemex Inc.

COG600535

Minor Permit

General Permit Covered Facility

Cement, Hydraulic

LaFarge West Inc.

COG500116

Minor Permit

General Permit Covered Facility

Construction Sand and Gravel

Lyons WWTP Upgrade Preliminary Engineering Report 3-3

3.3. Existing Facility Description

The current Lyons WWTP is a conventional plug flow activated sludge plant. As previously noted, most of the existing facilities were constructed in 1976. Section 3.0, page 13 of the Honeywell Report discusses the improvements that have been implemented at the plant over the last few years. Figure 3-1 shows a existing layout and aerial of the plant. Table 3.2 provides an overview of the existing facilities including design capacities, installation dates of major equipment, and an assessment of the equipment condition. The following sections will describe the facilities in further detail.

Table 3-2 Overview of Existing Facilities

Equipment Design

Capacity Installation

Date Equipment Condition

Headworks

Screw Screen 1.0 MGD 1976

Fair Condition – equipment in fair condition; however, there are operational problems. All of the screenings in the influent are not being removed by the screen press.

Parshall Flume 1.837 MGD 1976

Good condition – equipment in good condition; however, grit accumulates in the flume causing flow measurement inaccuracies.

Influent Pump Station Centrifugal Pump #1 1.296 MGD 1976 Fair Condition Centrifugal Pump #1 1.296 MGD 1976 Fair Condition Aeration Basin

Aeration Basin (structure)

- 1976

Condition unknown – Unable to assess the condition due to the inability to drain the aeration basin. Concrete cracking and exposed rebar and aggregate can be seen above the surface water elevation;

therefore, assuming poor condition of the structure.

Fine Bubble Diffusers

- 2000

Condition unknown – Unable to assess the condition due to the inability to drain the aeration basin. The original diffusers installed in 2000 are still in service.

Blower #1 - 2000 Fair Condition Blower #2 - 2000 Fair Condition

Lyons WWTP Upgrade Preliminary Engineering Report 3-4

Equipment Design

Capacity Installation

Date Equipment Condition

Clarifier

Clarifier (structure) 0.577 MGD 1976

Condition unknown – Unable to assess the condition due to the inability to drain the clarifier. Concrete cracking and exposed rebar and aggregate can be seen above the surface water elevation;

therefore, assuming poor condition of the structure.

Clarifier Mechanism - 1976 Poor Condition – Although some steel components have failed, the mechanism is still in service.

Returned Activated Sludge (RAS)/Waste Activated Sludge (WAS) Pump

- 1976 Poor Condition

Scum Pump - 1976 Poor Condition Ultraviolet (UV) Disinfection UV Disinfection Unit #1

0.4 MGD 2003 Good condition

UV Disinfection Unit #1

0.4 MGD 2003 Good condition

Biosolids Handling Facility Aerated Sludge Holding Tanks (structure)

- 1996 Fair Condition

Rotary Drum Thickener (RDT)

2.5 MGD 2008

Good condition - Manufacturer evaluated the RDT and reported that it is in good mechanical condition.

3.3.1. Preliminary Treatment

Preliminary treatment consists of the headworks facility and influent pump station. Section 3, pages 10 to 12 of the JVA Report discusses the details of the facility design, design capacity, and capacity limitations. Influent flow enters the plant through the headworks facility, which currently consists of a screen press, a manual bar screen, and a Parshall flume. The influent screen is a PRO-Equipment PRO-GUARD with ¼-inch openings, a hydraulic capacity of 1.0 MGD, and an integral screw auger that dewaters, compacts, and conveys the collected screenings. The manual bar screen has ¼-inch openings and is installed in parallel with the screw screen. The manual bar screen is only used for when the screen press is down for planned or emergency maintenance.

Lyons WWTP Upgrade Preliminary Engineering Report 3-5

Filtrate from the RDT and condensation from the clarifier dome flow into the influent channel after the screen press and combines with the plant influent. The combined flow is then measured with a three-inch Parshall flume and ultrasonic level sensor. As noted on page 10 of the JVA Report, a communitor to grind particles was originally located downstream of the Parshall flume; however, the operators have recently decommissioned the unit.

Flow then enters a 1,000-gallon wet well. Two 20 horsepower (Hp) centrifugal pumps, in an adjacent dry pit, pump the screened wastewater to the activated sludge facility. Each pump has a capacity of 900 gallons per minute (gpm) at 30 feet of total dynamic head (TDH) and equipped with a variable frequency drive

(VFD).

3.3.2. Biological Treatment

The single activated sludge treatment train is housed in a circular concrete basin, subdivided as follows: a central clarifier with aeration basins in the surrounding annular space. The mixed liquor (i.e. screened raw wastewater plus RAS) circulates around the outside of the clarifier before flowing into it for solids separation. Section 3, pages 12 to 16 of the JVA Report discusses the details of the facility design, design capacity, and capacity limitations. The aeration basin has an operating volume of approximately 200,000 gallons and an operating depth of 14 feet. The basin is equipped with Tideflex fine bubble diffusers installed in a grid system over five zones.

After biological treatment, solids are separated from the wastewater in the clarifier. Solids settle to the bottom of the clarifier and the clarifier rake mechanism pushes the sludge blanket to the RAS/WAS pump. The rake also collects surface scum, which it is then pumped to the aerated sludge holding tanks. The clarified effluent flows over the weirs and is sent to the UV disinfection system.

The RAS/WAS pump is an air lift pump that continuously pumps RAS to the head of the plug flow aeration basin and WAS to the aerated sludge holding tanks.

The scum pump is also an air lift pump with an unknown capacity.

3.3.3. Disinfection

After biological treatment, clarified effluent is disinfected via UV radiation.

Section 3, page 15 of the JVA Report discusses the facility design, design capacity, and capacity limitations. The UV system is a Trojan UV3000 PTP. The low pressure, low output system consists of two units. Each unit has seven banks with two lamps per bank. As noted in Section 3.2, the disinfected effluent is then discharged to the St. Vrain Creek.

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3.3.4. Solids Handling

The solids handling facility consists of two aerated sludge holding tanks, a RDT, and sand drying beds. Section 3, pages 15 to 17 of the JVA Report discusses the facility design, design capacity, and capacity limitations. The aerated sludge holding tanks are a two-celled basin with approximately 80,784 gallons of operational volume in each basin, assuming two feet of freeboard. This is a total of 161,568 gallons. The digester is equipped with on/off aeration and a manual decanting system.

Polymer is added to the stabilized sludge and then the sludge is thickened in a Hycor RDT prior to ultimate disposal at a landfill or land applied at a permitted site. Sludge is thickened and dewatered to approximately eight percent solids prior hauling. The sludge can be further dried on the sludge drying beds.

Currently, the plant is not thickening or drying the sludge; therefore, the sludge being hauled is at approximately one percent solids.

3.4. Wastewater Flow and Load Analysis

In addition to the wastewater flows and loads analysis in Sections 2.4 and 2.5, this section discusses infiltration and inflow (I&I) or dry/wet weather flow effects to the Town’s system. Given that approximately 50 percent of the Town’s collection system is comprised of vitrified clay piping, some I&I is expected. Since only quarterly reporting of WWTP flows and concentrations is required, the data is not sensitive enough to detect short term I&I events.

It is possible, however, to discern the presence of I&I from the current data.

Figure 3-2 below shows monthly flow and BOD loading for 2008 through the first part of 2012. BOD load is directly indicative of the number of users discharging into the collection system. In an ideal case, all flows within the collection system originate from individual sewer taps. In that case, BOD load and flow have similar annual trends (i.e. reflecting population rise, tourism, etc). The variation of monitored flow and load conditions from the ideal scenario provides a relative measure of determining the occurrence of I&I. If the BOD load increases or stays constant while plant inflow increases, water is likely to be infiltrating from a source other than the sewer taps. June of 2010 and September of 2011 are likely examples of a typical I&I occurrence. However, without more detailed flow and BOD data, I&I cannot be measured or confirmed with a reasonable degree of accuracy.

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Figure 3-2 Plant Influent Flow and Load

3.5. Financial Status

This section will describe the financial status of the current wastewater system including O & M costs, existing debt, rate structure and other capital improvement programs.

Table 3-3 below presents the Town’s current rate structure from the Town’s ordinances.

Table 3-3 Rate Structure Type of Consumer Monthly Charge per Unit

Residential consumer without Town-provided water service $92.50 base fee/month

All consumers with flat rate Town-provide water service $92.50 base fee/month

Residential consumers with metered Town-provided water service

$16.65 base fee/month plus an amount equal to the sum of the Consumer’s water usage for the utility bills issued January, February, and March, divided by 3; and then multiplied by

$5.50 for each 1,000 gallons of average water use for such three-month period

0.00

0.05

0.10

0.15

0.20

0.25

0.30

B O

D L o ad lb s/ d ay

F lo w

M G

D

Monthly Average Flow Monthly Average BOD Load

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Type of Consumer Monthly Charge per Unit

Residential consumers without metered Town-provided water service but equal to

$16.65 base fee/month plus an amount the sum of the Consumer’s metered with Town-approved meter to water usage for the utility bills issued January, February, and March, divided by 3; and then multiplied by $5.50 for each 1,000 gallons of average water use for such three-month period Non-residential consumers with metered Town-provided water service

$16.65 base fee/month plus an amount equal $5.25 for each 1,000 gallons of water use during such billing period

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SECTION 4

Project Purpose and Need As discussed in Section 1.1, a number of issues at the WWTP necessitated this project.

Some of the major issues are listed below.

Lack of redundancy Facilities and equipment at the end of operational life Objectionable odors High energy consumption and costs High costs for non-energy related operations and maintenance Compliance

This section will detail the compliance history, security, operational and maintenance issues, and growth and capacity.

4.1. Compliance History

Based on the Environmental Protection Agency’s (EPA) Enforcement and Compliance History Online (ECHO) database, the Lyons WWTP is currently designated as significant non-compliance/high priority violation (SNC/HPV).

The SNC designation, which is used for the Clean Water Act, is based on an automated analysis of DMRs submitted by the facilities or a manual generation of the designation. Generation of this designation may be based on a number of events. Examples of events are listed below.

Unauthorized discharges Failure to meet a construction deadline Failure to file a DMR Filing a DMR more than 30 days late

According to the ECHO database, the Lyons WWTP has mainly had permit schedule violations; however, the plant also had two discharge violations. The violation and the quarter of occurrence are listed below.

pH (January-March 2010) – numeric violation, pH concentration below 6.5

Temperature (July-September 2012) – numeric violation, temperature greater than 20 °C

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The SNC designation can be removed once the plant shows a consistent pattern of compliance or once the EPA or state agency acknowledges the entity addressed the violation.

Currently, the Lyons WWTP is in compliance with its permit requirements;

however, the Town must monitor the regulatory environment to ensure the plant stays in compliance. Except for effluent temperature, it is not anticipated that there will be major changes in effluent limits when the permit is next renewed in 2014. However, CDPHE has recently adopted nutrient limits in Regulation 85, Nutrient Management Control Regulation and Regulation 31, The Basic Standards and Methodologies for Surface Water. The Lyons WWTP is currently exempt (at least to year 2022) from the effluent total phosphorus (TP) and total inorganic nitrogen (TIN) limits listed in Regulation 85 since the maximum month capacity rating of this facility is less than 1 MGD. Numeric in-steam TP and total nitrogen (TN) standards set forth in Regulation 31 will start to go into effect in 2022 and these could impact the Lyons WWTP in the future. The plant could also be forced to remove nutrients to a low level if the receiving stream is designated as impaired for nutrients and a total maximum daily load (TMDL) is established.

TMDLs apply to all plants, no matter how small they might be. Therefore, even though the plant does not currently have to comply with nutrient limits arising from Regulations 85 and 31, it is essential to take into account the new requirements when selecting an alternative.

In addition to the changes in regulatory requirements, the JVA Report, page 20 noted some additional compliance aspects of the project, which are listed below.

Implement corrective measures to ensure the permitted organic loading rate is not exceeded

Resolve odor and noise issues generated by plant processes Mediate floodplain issues

4.2. Security

There are no anticipated additional security measures that are required for the selected alternative. The Lyons WWTP is surrounded by an eight-foot high chain link fence and security gates with barbed wire to restrict access to authorized personal. The security gate is only accessibly by a numeric access code, which is changed every three days.

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4.3. Operation and Maintenance

Operators have a number issues operating and maintaining the facilities and equipment at the plant. Section 4, pages 15 to 17 of the Honeywell Report discusses the operational and maintenance issues. Some of the main issues are:

Lack of redundancy – As noted in the Honeywell Report, the lack of redundant facilities and equipment can lead to the inability to perform preventative or emergency maintenance, potentially resulting in permit violations. For example, the fine bubble diffusers in the aeration system have not been cleaned, repaired, or replaced due to the lack of an additional biological treatment train. This leads to inefficient aeration and the use of more energy than would otherwise be required.

Lack of an automated control system – As noted in the Honeywell Report, there is a lack of automation at the plant; therefore, many of the units are operating inefficiently. For example, the influent pumps and blowers are operating in “Hand” mode.

4.4. Growth and Capacity

As…