2008 Facility Plan Update

May 2008

Purpose

Comprehensive Plan through 2033– Builds on Past Work– Adjust for Changing Conditions

Identify Capacity, Compliance, and Rehabilitation needs– Robert W. Hite Treatment Facility– Biosolids Management Program– Transmission System

Develop Cost-Effective Capital Improvement Program– To meet Future (more stringent) Effluent Quality Requirements – Accommodate Growth

Renewal 2003 Wastewater Utility Plan– Denver Regional Council of Governments (DRCOG)

Updates 2003 Wastewater Utility Plan

Defines South Secondary Improvements (PAR 1085)

Updates Transmission System InfoWorks Model

Updates 2007 Land Use Model

Updates Plant GPS-X and Hydraulic Models

Includes PELs from Future Effluent Limits Study

Updates 2003 Facility Plan & 2002 Service Area Utility Plan, and 2007 Biosolids Study

Incorporates North Secondary Improvements (PAR 942)

What’s Included in 2008 Update

Does not include IS/Support facilities

South Secondary Improvements

Parallel Track– Ammonia Compliance Deadline December 31, 2014

Jan 08

South Secondary Predesign

Define South Secondary Needs

Jun 07 Jul 07

Technical Team Review

Develop Alternative Layouts and Costs

Aug 07

Begin Facility Plan

Feb 07

Complete Facility Plan

Mar 08

Complete Predesign Mar 09

Metro District Service Area

615 square miles and includesCity and County of Denver and parts ofAdams, Arapahoe, and Jefferson counties

Six Drainage Basins

Member Municipalities and Special Connectors

20 Member Municipalities and 25 Special Connectors

Metro District Service Area Including Brighton and South Adams

Population and Employment Projections

Projections based on:– Updated Member Municipality & Special Connector information– Current population, employment & boundary information from DRCOG

TAZ Data (Transportation Analysis Zones)– Buildout projections from the Land Use Model

Population – Increase 39% or 1.5% per year thru 2033 Employment – Increase 52% or 2.0% per year thru 2033

Parameter 2007 2015 2033 Buildout

Population 1,588,000 1,745,000 2,213,000 2,833,000

Employment 985,000 1,190,000 1,492,000 2,371,000

Population Equivalent

1,785,000 1,983,000 2,511,000 3,307,000

Flow and Load Projections

Parameter 2007 2015 2033 Buildout

Flow, million gallons per day (mgd)

147 164 208 227

BOD load, tons per day (tpd)

167 187 237 262

TSS load, tpd 180 199 252 276

TKN load, tpd 23.4 26.1 33.2 36.7

Unit Flow Factors– 85 gallons per capita per day– 17 gallons per day per employee

Developed Service Area Projections Adjusted to Determine Primary Influent Flows and Loads

– Exclusion of area tributary to a future Box Elder WWTP– Reduction in flow of 5 mgd for the Sand Creek Water Reclamation Facility– Additional loads, such as in-plant and hauled wastes– Increase in BOD loads from DIA

Historic and Projected Primary Influent Flow and Loads

Existing Robert W. Hite Treatment Facility Liquid Stream Capacity

Current max month rated capacity 220 mgd with EPC (~185 mgd Annual Average) Capacity without EPC 161 mgd Annual Average (Secondary Treatment) North and South Secondary Expansions required to meet capacity and regulatory requirements RWHTF AAF capacity needs to be 210 mgd in 2033

Existing Robert W. Hite Treatment Facility Solids Stream Capacity

Improvements to the digesters and high-solids centrifuges are planned during 2008-2013.

Existing Transmission System Summary

219 miles of interceptors, 12 miles of force mains and 4 lift stations

Capacity evaluation based on:– Previous modeling from 2002 SAUP– Updated Land Use Model– Updates to existing InfoWorks Model

0.040.04-0.10

33-8

Phase 5 Beyond 2023

Discharge Permit Requirements Anticipated to Remain Unchanged Through Planning Period

3Minimum dissolved oxygen, mg/L

6.0-9.0pH range, standard units

0.011Maximum chlorine residual, mg/L

30TSS, mg/L

17CBOD, mg/L

–8.68

–

–8.68

–

Nitrates (plus nitrites), mg-N/L Daily maximum 7-day average 30-day average

6.2-12.71.7-2.22.0-4.6

21.5-30.0 –

9.7-15.0

Total ammonia, mg-N/L Daily maximum 7-day average 30-day average

Discharge Permit Requirements Anticipated to Change in Phase 2

Phase 32013-2018

Phase 22008-2013Parameter

0.50.04-1.0

Total phosphorus, mg-P/L Phasing Assumption Assumed Range

83-8

Total nitrogen, mg-N/L Phasing Assumption Assumed Range

Phase 4 2018-2023Parameter

Discharge Permit Requirements Anticipated to Change in Phases 4 and 5

Regulatory Assumptions

Improvements and Project Implementation

Transmission System improvements driven by rehabilitation needs and capacity constraints due to growth

RWHTF improvements phased over planning period to meet capacity, regulatory, and rehabilitation needs

Used recently developed Metro District Cost Estimating Guide for consistent and better cost estimates

Recommended improvements “packaged,” according to type, location, and timing

– Construction Efficiencies– Save Capital Costs

Goal of the phased program is to continuously meet customer service and regulatory requirements through the end of the planning period

Transmission System Rehabilitation

Inspection Program– Closed-circuit television and surface inspections– CCTV inspection annually on portion of system– CCTV taping of each interceptor every 10 years– Three categories based on degree of degradation

Transmission Division reviews to assess condition Engineering Department performs second review,

further refines the condition, develops a cost estimate and schedule

Transmission System Rehabilitation

CIPP Slip Lining Manhole Rehab

Transmission System Capacity Improvements

Transmission System hydraulic modeling– 2002 model updated with Sand Creek Basin

Wastewater Master Plan– Model updated with revised population,

employment, and unit flows– Model runs performed for 2007, 2015, and 2030– Assumed northeast Service Area flows will

continue to RWHTF – Flow data being collected to further refine model

calibration in 2008

Metro District Transmission System Capacity Concerns in 2015

Metro District Transmission System Capacity Concerns in 2030

Transmission System Project Implementation Schedule

Basis for RWHTF Recommended Improvements

2003 Facility Plan established basic direction– Five-stage air-activated sludge with BNR– Phasing out the high-purity oxygen system

North Secondary Improvements Project (PAR 942)– CaRRB process to address centrate treatment

Objective is to have similar processes in the North and South Complexes that operate and perform in a comparable fashion

RWHTF Recommended Improvements

RWHTF Project Implementation Schedule

Projected Capital Expenditures

$1.86 billion projected 2008-2033 $1,528,000,000 – RWHTF $332,000,000 – Transmission System

Questions

RWHTF Buildout Site Plan (230 mgd)