North System Renewal Water Treatment Plant Project (NSRWTP)

Presented by: Zack Alabbasi and Andrea Song

JTAC LuncheonMay 15, 2014

History of Moffat WTP

• David Moffat (July 22, 1839 – March 18, 1911)

• Born in Washingtonville, New York.

• Moved to Denver in 1860.

• Formed a railroad company in 1867 to link Denver to the national rail network.

• Denver relied on rivers, ditches and wells until about 1872, when a private water company was franchised. Kassler Plant (first plant) was built in 1890.

• Soon, several water companies were operating in the city. In 1894 they were consolidated as the Denver Union Water Co., headed by Walter Cheesman and David Moffat.

• The citizens of Denver purchased the company in 1918 for $14 million dollars (bond issue).

History of Moffat WTP

• A vision of David Moffat, the Moffat Tunnel (linking Denver to Salt Lake City and the west coast) was a railroad and water tunnel.

• Cost $24 million and 28 lives to build.

Benefits of the Moffat Tunnel as outlinedin Nov 1922 issue of Popular Science magazine

• The first train passed through the tunnel in February 1928. The 6.2 mile tunnel shortened the distance between Denver and the west coast by 176 miles.

History of Moffat WTP

History of Moffat WTP

Moffat Water Treatment Plant 1930s10 filters – 50 MGD capacity

Mayor Stapleton commissioning the Moffat Water Treatment Plant in 1937

History of Moffat WTP

Filter plant 1 (1937): 10 rapid sand filters. Total capacity = 50 MGD

Filter plant 2 (1955):10 rapid sand filters. Total capacity = 75 MGD

Filter plant 3 (1974):8 rapid sand filters. Total capacity = 60 MGD_______________________________________________

Total capacity = 185 MGD

History of Moffat WTP

Water Source (Denver Water)

Gross Reservoir

Outlet at Gross Reservoir

Ralston Reservoir

The Upper Williams Fork and Fraser River basin supply Gross reservoir (through the Moffat tunnel)

Gross reservoir supplies Ralston Reservoir (through South

Boulder Creek)

Ralston Reservoir supplies Moffat WTP via conduits 16 and 22

Water Source (Moffat WTP)

Gross: 41,811 acre-foot or 13.6 billion gallons

Ralston: 10,776 acre-foot or 3.5 billion gallons.

Ralston reservoir is 6046 ft. (full)Ralston valve is 5950 ft.Van Bibber is 5840 ft.Moffat is 5623 ft

96 ft110 ft

217 ft

423 ft = 183 psi

Storage Capacity (Moffat WTP)

RalstonReservoir

UpperLongLake

lowerLongLake

Ralston Reservoir

Conduit 16 is 42-inch concrete pipeline constructed in 1937.

Conduit 22 is 54-inch concrete pipeline constructed in 1950.

Raw Water Transmission Pipes

Aluminum Sulfate (Alum) CoagulationPotassium Permanganate OxidationCalcium Hydroxide (Lime) pH adjustmentCarbon Dioxide Alkalinity, and

pH adjustmentDADMAC (Cationic polymer) Coagulation-aidPolyacrlyamide (Nonionic polymer) Flocculation-aid,

filter-aid and sludge de-watering

Sodium Silicofluoride (Fluoride) FluoridationSodium Hydroxide (Caustic Soda) pH AdjustmentChlorine DisinfectantAmmonium Hydroxide (Ammonia) Disinfection aid

Treatment Chemicals

Treatment Process

RalstonReservoir

GravityThickener

Waste ResidualSolids

Spent Backwash

Drying Lagoons

(Ralston)

Landfill

Gra

vity

Thi

cken

er S

uper

nata

nt

Supe

rnat

ant/o

verf

low

(occ

asio

nal)

BackwashEqualization

Basin

Spen

t Bac

kwas

h

South Boulder Canal

Off-site Disposal

Flocculation / Sedimentation

Distribution System

DisinfectionContact Basin

Finished WaterStorage

Filtration

Filtration

Drain

Drain

RapidMix

Floc/Sed Drain

Pump Station

Pump Station

Filter to waste

Filter Drain

Alum, Lime, Carbon Dioxide, Potassium Permanganate, Polymer Polymer

Polymer, Chlorine

Chlorine, Fluoride, Ammonia, Caustic SodaPolymer

Aeration

Drying Lagoons

(41st & Independence)

Clear Creek

Plant drainage, Storm water

Dechlor

Treatment Process

North System Renewal Program

Future of Moffat WTP

North System Renewal Program:

• Raw Water Collection System (Gross Reservoir Expansion)

• Ralston Reservoir Multi-Level Outlet

• Conduit 16 Replacement

• North System Renewal Water Treatment Plant Project (NSRWTP)

North System Renewal Water Treatment Plant Project (NSRWTP)

• Rebuild of the Moffat WTP

Why Moffat TP? Why Now?

• Parts of Moffat reaching end of its useful life

MOFFAT FILTER GALLERY

Why Moffat TP? Why Now?

31”

MOFFAT WTP MONO MEDIA

20”

4”4”3”

42”

MARSTON WTP DUAL MEDIA

34”

8”

• Current Technology– Dual Media Filtration

• Outdated Technology– Mono Media Filtration

Moffat WTP Through the Years

Road Map for NSRWTP

Program Schedule for NSRWTP

Plant Site Selection

Moffat Site - Property Owned by DW

Moffat TP Site~ 40 Acres

YMCA Site~ 8 Acres

Ralston Site~ 1,033 Acres

Ralston Reservoir Site - Property Owned by DW

Plant Site Selection

• Determine the best course of action:

RALSTON SITE?MOFFAT SITE?

OR

Moffat Preliminary Evaluation

• Parts of the plant reaching end of its useful life.

• Outdated filtration technology (mono media filtration).

• Replace Moffat TP in a planned manner To plan and adjust long range capital budget Consider needs of all stakeholders

Evaluation Process:

• Two locations (Moffat and Ralston) and two treatment technologies are considered in the evaluation (dual-media, membrane, hybrid).

• Condition Assessment (existing plant), Cost Comparisons (both sites and both technologies), Non-Monetary Criteria (both sites)

• 250 MGD capacity

Moffat Site - Dual Media Filtration

Reservoir 3

Reservoir 2

Moffat Site - Dual Media Filtration

KEY:

PHASE 2PHASE 1

FUTUREPHASE 3

Moffat Site - Dual Media Filtration

Ralston Preliminary Evaluation

Proposed Construction Site

Ralston Site - Dual Media Filtration

Ralston Site - Dual Media Filtration

The Numbers - Comparison

The Numbers - Comparison

$370,000,000 Construction Cost

6 Years of Construction

~15,000 Truckloads of material & equipment

108,600 CY Concrete poured

91,500 CY Backfill

85,600 CY Excavation

47,280 CY Concrete demo and crushing

$444,000,000 Construction Cost

3.5 Years of Construction

~22,000 Truckloads of material & equipment

178,200 CY Concrete poured

614,000 CY Backfill

>1,000,000 CY Excavation

Moffat 250 MGD – Dual Media Ralston 250 MGD – Dual Media

0 CY Concrete demo and crushing

Monte-Carlo Analysis

Treatment Process Selection

North System Renewal Water Treatment Plant Project (NSRWTP)

• Developing WQ goals for treatment process selection

Developing WQ & Treatment Goals for NSRWTP

• Technical Panel• CU, CSU, Mines• WRF Wildfire Study

• Future Uncertainty• Gross Reservoir Expansion• Extreme weather events

• Adopted Partnership for SafeWater Goals

Debris in StrontiaSprings Reservoir after Hayman Fire

2002

Gross Reservoir atheight of drought

2002

Storm Event of September 2013

• Lessons learned will be incorporated in future plant design standards

Ralston Reservoir Flood 2013

Slide Area Auxiliary Spilllway

• Think beyond the WTP

• Expanding reservoir monitoring program

• Source Water/Distribution System Evaluation

GROSS RESERVOIR

Storm Event of September 2013

• Completing desk-top evaluations and then fast and economical bench-scale tests

• To help narrow down treatment alternatives for pilot testing

Treatment Process Selection for NSRWTP

Current Treatment Process Train

Cl-NH3

Finished Water

DisinfectionRapid-Mix &

FlocculationSedimentation

Granular Media Filter

Raw Water Intake

Wat

ersh

ed C

ontr

ol S

trat

egy

CoagulantPolymer

pHAlkalinity

Fluoride

pH Corrosion Inhibitor?

Treatment Process Selection for NSRWTP

Enhanced CoagulationBiological Filtration

Raw Water Intake

Watershed Control Strategy

Riverbank Filtration Watershed

Master Plan

Cl-NH3

DisinfectionRapid-Mix &

FlocculationSedimentation

Granular Media Filter

CoagulantPolymer

pHAlkalinity

Fluoride

pH

Corrosion Inhibitor?

Pre-coagulant

Ozone

Finished Water

Settled Water Ozone

UV orOzone

OrMF/UF

MembraneGAC

Future Treatment Process Train

Treatment Process Selection for NSRWTP

AOP(Peroxide)

AOP(Peroxide)

AOP(Peroxide)