HomeMy WebLinkAbout4 - Biosolids Dewatering and Composting ProjectCITY OF BOULDER
WATER RESOURCES ADVISORY BOARD
M~ETING DAT~: August 18, 2003
SUBJECT: Agenda Item• Biosohds Dewatering and Compostmg Project
REQUESTING DEPARTM~NT: Public Works/Utilities
Ned Williams, Pubhc Works Director for Utihties
Bob Harberg, Utilities Pro~ect Coordmator
Presenter: Douglas Sullivan, Utihties Pro~ect Manager
Floyd Bebler, Coordmator of Wastewater treatment
Paul Heppler, Resource Recovery Specialist
BOARD ACTION REQUESTED: None. Staff is using this meetmg to piovide the WRAB
with a project overview and update. Staff will be returmng to the October 20, 2003 WRAB
meeting w~th a Community and Environment Assessment Process (CEAP) asking for a final
recommendation which will be presented to the Planning Board and City Council in
November and December 2003 iespectively.
FISCAL IMPACT: Utilities has budgeted $1 5M for the study/design phase for 2003/2004,
and $15M for the project construction in 2004/2005.
PURPOSE
The purpose of this Agenda item is to provide the Water Resources Advisory Board (WRAB)
with a Biosolids Dewatermg and Composting Project update
EXECUTIVE SUMMARY
The City of Boulder is currently addressing the need for improved WWTP biosolids treatment.
The City has been evaluating alternative treatment ophons since 1997, when rt hired RTW
Engmeers to complete a Biosolids Management Study The study mcluded an evaluation of 10
Class A biosohds stabilizahon processes.
AGENDA ITCM # Paee 1
In 2000, the City of Boulder purchased a 100-acre site in the vicinity of Valmont Butte (Valmont
Road and 61S` Street) The acquisition was alotnt purchase of the Publrc Works, Fire, and Open
Space and Mountain Parks (O5MP) departments, with approximately 1/3 of the acreage
allocated for each department. The purpose of the acgmsttion is to serve as a locatron for a
future Brosohds Dewatermg and Compostrng Facdtty, a relocatron of the fire training center,
with OSMP providing a land buffer along the srte perimeter between future facditres and
Valmont Road
Public Works hired RTW Engineers to November 2002 to desrgn a Brosohds Recycling Center
(BRC) which wdl include dewatermg and composting facilities.
BACKGROUND
The Crty of Boulder's current W WTP btosolids treatment program involves Class B anaerobic
digestion. The solids are then dewatered to 10% and trucked 65 miles east w Adams County
where they are land applied. The Crty has been land applyrng biosolids in Boulder County as a
soil condthoner to agrrcultural farms since 1980, when the anaerobic drgesters were constructed
at the WWTP. The Crty began land applyrng biosolids m eastern Adams County m 1995.
The City has been considering alternative brosolids treatment programs for many years for two
primary reasons: 1. the Crty has been a leader in the brosolids industry on a national level since
the late 1980's, and wishes to remain a front runner m addressing brosolids recycling, and 2 the
existing program's long-term viability rs in question as there are fewer land application sites
available every year. Natronal biosolids trends are leading to brosolids product that can be
returned to the stakeholders as a fertilizer for home and garden use
The current study/design is a follow-up to the 1997 Brosohds Management Study addressing the
Crty's needs to develop an alternative brosolids treatment program.
BIOSOLIDS DEWATERING AND COMPOSTING PRO.iECT
The Brosohds project Scope of Work includes the following tasks alternatives analysts,
permitting and annexation support, addttronal capacity partners (neighborhood communities)
evaluatron, preliminary desrgn and final design and constructron inspection services
Alternatives Analysis
The Alternatrves Analysis task involved evaluating various key engineering issues including
btosolids transport and compost treatment options. The analysis included a capital and
operations costs evaluation as well as anon-monetary criteria evaluatron. The two transport
options included trucking versus piping. Both trvtsport alternatives would require new
dewatering facdtttes and new composting faciliries at either locatron.
AGENDA ITEM # Paee 2
1. The trucking option would involve dewatering the digested biosohds at the 75i~' Street
WWTP and trucking the solids to the new BRC. The trucking would require several
weekly tops and involve a 5-mile roundtrip along 75`h Street and Valmont Road.
2 The piping optron would involve the construction of 6-inch pipeline which would
convey the brosohds (2%) from the WWTP to the BRC. Two pipeline alignments
were evaluated for this optron, varying from 1.5 miles to 2.5 miles in length.
The RTW team evaluated two compost processes for the Alternatives Analysis The two
processes evaluated included Aerated Static Pile (ASP) and Horizontal Agitated Bed (HAB)
technologies.
1. The ASP process involves constructing rows of compost pries. The pries are
aerated from below by a piped system. The ASP process generally requires a
moderate amount mechanical equipment but iequires a greater amount of staff
labor.
2. The HAB process requires the construction of long concrete bays which are used
to house the compost material. The HAB process utilizes an agitator, which
moves along steel rails located atop the bay walls, to mix the compost, along with
substructure aeration. The HAB process requrres greater capital expenditure but
requires less labor.
City staff and consultants inspected five facilities in Iowa and North Carolina m a December
2002 site tour. The purpose of the site tour was to visit existing W WTPs, whrch feature the
recent dewatering equrpment and compost facility processes installations.
The RTW team has begun conducting various geotechnical evaluations at the Valmont Butte
Site. These evaluations include drilling three (3) geotechnrcal wells and three (3) groundwater
monitoring wells The geotechnical wells will provide soil boring data for the facrhties' design
The groundwater monitoring wells will be used as part of an ongoing monitoring program to
various site water quality issues
The RTW team has completed an odor dispersion modeling study for the proposed dewatering
and compost facilities to be located at the Valmont Butte site. This study was completed to
evaluate the facility's potential odor generation and also to evaluate potential odor dispersion to
the surrounding area.
Additional Capacity Partners
This task involved reaching out to neighboring communities to identify the level of interest of
others potentially contributing biosolids to the BRC. City staff and Consultants met with
representatives from Longmont, Louisville, Lafayette, Niwot, Erie and Superior Interest levels
varied across the communities. Longmont identified the strongest mteiest as they are in the
process of closing their compost facility due to residential development encroachment issues.
Several communities expressed interest, but noted that a financial commitment would be
problematic. This task work is summarized in RTW's Technical Memorandum No 2
AGENDA ITEM # Pave 3
Permittine & Annexation
The Biosohds Dewatering and Composting protect will require City annexation of the Valmont
Butte site and various permitting requirements including a CEAP, site review, and Certificate of
Desrgnatron (CD). The City is in the early stages of the annexatron process. The 5rte revrew
will follow the annexation. Staff will present the LEAP at the October WRAB Meeting. The
CD, whrch was submitted m August 2003, rs requrred by the State of Colorado as biosohds
treatment facrhties are subject to solid waste regulations
Schedule
The following is a project's protected schedule.
Preliminary Design -August 2003 through October 2003
Final Design -November 2003 through May 2004
Construction -June 2004 through December 2005
Conclusions
The RTW team has recommended that the City construct the pipeline Co transport biosolids from
the BWWTP to the BRC. Additionally, RTW recommends that the City select the Horizontal
Agitated Bed compost technology.
STAFF RECOMMENDATION
There are no recommendations at this time City staff concurs with the RTW team
recommendations.
ACTION REQUESTED
Staff and the RTW team have rdentified several key project and potential community issues
which include. potential odor generatron, increased traffic, cemetery access, prairie dog removal,
municipal airport issues, and increased noise. Staff requests that the WRAB identify key issues
of concern at this meeting so that staff can adequately address the issues when staff returns for
the October meeting wrth the LEAP to make a more comprehensive presentation.
ATTACHMENTS
1. WRAB Biosolids Protect Meeting Agenda Outline
If you have any questrons regarding the Valmont Butte site or the BRC, please contact Douglas
Sullivan at extensron 3244 or e-marl at sullivand@cr.boulder.co us
AGENDA ITEM # Paee 4
Biosolids Dewatering and Compost Project
Water Resources Advisory Board Meeting
August 18, 2003
Agenda Outline
I Introduction
II. Overview
a 1997 Brosolids Management Study -Recommendations
r City owned and operated In-vessel compost facrhty at BWWTP
ii Ptlot Study (1997-2001) -BWWTP to convey 15% of annual
solids production to A-1 Organics Lost Antlers Compost Facrlity
in Golden, Colorado
b. Current WWTP solids residuals program
i. Class B Land application -digested sludge dewatered to 10%
solids and trucked 65 miles to Adams County
III. Valmont Butte Site
a. City purchased 100-acre site rn 2000 - (Joint purchase of Open Space,
Fire Dept. and Public Works at 1/3 acreage each)
b. PW (Biosolids Recycling Center), FD (fire training center) and Open
Space (land buffer)
c Phase I Envrronmental Assessment -September 2000
d. Valmont Butte Srte Environmental Report - 1996
IV Biosolids Dewatering and Compost Protect
a. RTW Team hired in November 2002
r. Tetra Tech - compostrng
u. Hazen & Sawyer - centrifuge
iu. Terracon - geotechnical
b. Scope of Work/Schedule
i. Alternatives Analysis (Spring - Fa112003)
u Addrtronal Capacity Partners - (Spring - Fa112003)
m Permitting/Annexation (Fa112003)
iv Preliminary Design (Aug -Oct 2003)
v Final Desrgn (November 2003 -May 2004)
vi Construction (June 2004 -December 2005)
V Design Issues
a Alternatrves Analysis
i. Biosolids transport (trucking vs prping)
u. Pipeline Alignment Alternatives
in. Compost Technology -Aerated Static Pile (ASP) vs. Horizontal
Agitated bed (HAB)
iv Odor Control Modeling
v. Geotechnical Analysis
vi Centrifuge Pilot Testing
b Addrtronal Capacity Partners
r. Longmont, Lafayette, Loutsville, Nrwot, Erte, Superior
ri. Facthty Capactty (10 dtpd vs. 20 dtpd)
ur. Shared Funding
c. Public Process/Permrts
i. Annexatron
ri. Site Review
ut. CEAP
iv. Certificate of Designation (CD)
v County ] 041 Permit (?)
VI. Summary
a. Key WRAB issues
b. October WRAB Meeting