R01-176 RESOLUTION NO. R01- I'?k,
A RESOLUTION OF THE CITY COMMISSION OF THE
CITY OF BOYNTON BEACH, FLORIDA, AUTHORIZING
THE MAYOR AND CITY CLERK TO EXECUTE TASK
ORDER NO. 6 BETWEEN THE CITY OF BOYNTON
BEACH AND CH2MHILL FOR ENGINEERING SUPPORT
SERVICES FOR THE DEVELOPMENT OF AN
OPTIMIZATION PLAN FOR THE EAST WELLFIELD
INCLUDING AQUIFER STORAGE AND RECOVERY
WELL PRELIMINARY DESIGN AND PERMITTING; AND
PROVIDING AN EFFECTIVE DATE.
WHEREAS, this Task Order will include the modeling, and installation of "sentinel
yell" to provide the early detection of any possible saltwater intrusion into the City's eastern
wellfield; and
WHEREAS, the information gathered fi.om the modeling and the new sentinel wells
will be used to develop a wellfield response plan intended to minimize saltwater intrusion, as
well as provide for the preliminary design and permitting of two additional Aquifer Storage
and Recovery wells that could be used to store treated water during rainy periods, for
recovery during droughts or dry weather;
NOW, THEREFORE, BE IT RESOLVED BY THE CITY COMMISSION OF
I'I-IE CITY OF BOYNTON BEACH, FLORIDA, THAT:
Section 1. The City Commission of the City of Boynton Beach, Florida does
hereby authorize and direct the Mayor and City Clerk to approve and execute Task Order No.
6 with CH2MHILL for engineering support services for the development of an Optimization
Plan for the East Wellfield, including Aquifer Storage and Recovery Well Preliminary
Design and Permitting.;
Section 2.
This Resolution shall become effective immediately upon passage.
PASSED AND ADOPTED this [ day of May, 2001.
ATTEST:
(C o~)~al~3~e~r)
Commissioner
ACH, FL?R1DA
.~ ....
Commissioner
Commissioner
PROPOSAL FOR ENGI;;.","'RING SERVICES
Engineering Support Services for
The Development of an Optimization Plan for
the East Wellfield Including Aquifer Storage and
Recovery Well Preliminary Design and
Permitting
Task Order No. 6
Prepared for
City of Boynton Beach
March, 2001
CH2MHILL
Optimization Plan for the East Well Field
Including
Introduction
The City of Boynton Beach (City) is concerned about the potential for saltwater intrusion in
the City's East Well Field and has sought the assistance of CH2M HILL in establishing
monitoring wells that will serve as ,sentinels" to alert the City as to changes in the
groundwater level and/or quality. In order to minimize saltwater intrusion, a sufficient
head (elevation) of fresh water must be maintained between the wellfield and the saline
water source. This study will determine the location of fresh/saline water interface,
estimate the required freshwater head necessary to protect the East Well Field, and establish
an operations ~ian for maintaining this head. Part of the operations plan will involve the
use an additional 5 to 10 million gallons per day of Aquifer Storage and Recovery (ASR)
well capacity to decrease the City's dependency on the East Well Field during dry periods
when the potential for salt water Intrusion is greatest.
The goals of this project are to:
· Identify suitable locations for the sentinel wells,
, Determine what water levels and/or quality parameters will indicate an increased
potential for saltwater intrusion, and
· Develop a response plan that will be enacted if data from the sentinel wells indicate an
increased potential for saltwater ~trusion
Determine the appropriate ASR wellfield configuration to maximize the recovery
efficient of a multi-ASR well system.
· Prepare a preliminary design for the additional ASR capacity.
· Provide permitting services for the additional ASR well(s).
This project is divided into two phases that can run concurrently. The first phase is the
development of an operating plan for the East Well Field and is divided into four tasks
(Tasks A through D) with an optional fifth task (Task E). Task A is data review and
compilation. This Task will be used to develop a conceptual model of the East Well Field
area and frame the hydrogeologic setting. The second task (Task B) incorporates the data
assembled in Task A and develops a cross-sectional model that will be used to simulate the
saltwater front alOng an east-west axis and determine the optimum distance for locating the
sentinel wells. Task C consists of the development of a three-dimensional MODFLOW
model that will be coupled with an optimization program (MODMAN) and used to develop
a targeted pumpage management plan that can be implemented in response to water level
(and/or quality) conditions encountered in the sentinel wells. The fourth task (Task D)
consists of the installation of the sentinel wells. An optional fifth task (Task E) covers the
refinement of the models (if' deemed necessary).
The second phase of the project is the preliminary design and permitting services for
additional ASR well(s). Groundwater modeling will be conducted to simulate and predict
potential hydraulic impacts of operating a multi-well ASR system with the desired capacity.
These data will be used to design an ASR wellfield (the existing ASR well plus one or two
additional wells) configuration that will maximize recovery efficiency while taking into
account the affects, of hydraulic interference between the ASR wells. These data will then be
used for the ASR, , and preparation of ASR well(s) construction
permit applications construction permits
from~ (FDEP) and the Palm Beach
Count]
Scope of Services
Task A -Data. review and collection
Data Collection
CH2M HILL staff will obtain data on the hydrOgeology of the Boynton Beach area from a
variety of sources, including (but not limited to): the City of Boynton Beach, United States
Geological Survey (USGS), the South Florida Water Management District (SFWMD), and
additional technical reports describing the area of interest. The following data will be
collected:
· Groundwater levels
· Canal stages
· Precipitation rates
Evapotranspiration rates
· Aquifer hydraulic properties and lithology
· Pumping rates, and
· Water quality data related to saltwater intrusion
Data collection will focus on obtaining an understanding of the hydrogeologic system in the
model area. Effort will be made to obtain contemporaneous, spatially distributed data that
can be used for model calibration.
Cross-section model selection
The available data will be reviewed to assess the suitability of various groundwater
modeling codes for use in simUlating a cross-section of the saltwater front along an east-
west axis. Exhibit A lists several model codes that will be considered as part of this task.
Exhibit A Model codes
:M°del Source Dimensionality SolUtion ! Steady state ' Variable
MethOd , /transient density
HST3D ' USGS 3-D ~Finite r ~' T · ' Yes r
difference
SW1~-98 ",'HSi r ; 3-:D ~, ~ Finite'" SS T yes :
GeOtrans : ,differenCe '
element ~ , '
GMSZ ,: ,~EMSI : 3.D ,; ' ;:':' ss;T ; Yes' 'r :
FEIVlWATER , ; ~ element ,
MOCDENSE USGS:, ,i,"2-D ' Fini{e : ~; : T: yes ' ' ~
,. ,, , ,.: , :, ~: i ' ~ dfference ;': ! ' ,
sHARp usgs Quasi 3-D Finite r , yes = '
difference
* FEMWATER interface costs $500. The
The available data will be reviewed and the appropriate model will be selected. The; model
selection process will also include the review of similar case studies and ;with
CH2M HILL modeling experts who have extensive experience in simulating ,,
intrusion.
Deliverable
The deliverable for this task will consist of a technical memOrandum, that:
· Summarizes the data collected,
· Describes the conceptual model of the East Well Field area
· Identifies the model code that will be used for the cross-sectional model of the saltwater
interface and the rationale for its selection.
Task B - Saltwater interface modeling
That data collected in Task A will be used to develop a cross-sectional model of the
saltwater interface. The modeling objectives are to:
· Develop a vertical profile of the saltwater interface based upon data obtained in Task A,
· Establish locations (distances) for "sentinel" wells,
· Determine the appropriate sampling intervals for the "sentinel"wells
It is anticipated that the model domain will be a narrow, vertical cross-section, oriented
along an east-west axis. Due to the potential for vertical flow, it is likely that a three-
dimensional model will be used. However, the model alignment will be chosen based upon
the available data so as to minimize gradients that are not parallel with the long axis of the
model.
Model development
The model grid, boundaries, aquifer properties, etc. will be developed based upon the data
collected in Task A. It is expected that the model axis will run parallel with Woolbright
Road so as to intersect the saltwater interface perpendicularly. The exact model domain and
orientation will be determined based upon data collected in Task A, so as best to model the
saltwater interface. However, the location of production and monitoring wells immediately
south of Woolbright Road makes this the most likely model location. Cell sizes and
orientation, aquifer properties, etc. will be based upon the data collected in Task A.
Model' calibration
It is expected that the model will be calibrated to transient conditions, based upon the City's
and water levels. Ideally, the model will reproduce the
the saltwater interface observed over the past several years. A
sensitivity analysis will be performed upon the calibrated model.
S~ntinel Well siting simulations
The anticipated future operation of the wellfield will be simulated to identify distances for
siting the sentinel wells. In addition to linear distance from the wellfield, the model
t zones of interest that will be monitored by the
are .available.
Deliverable
The deliverable for Task B will consist of a technical memorandum describing the model
development and predicative simulations. Cross-sectional diagrams of the saltwater
interface and proposed monitoring well locations and screened intervals will be included.
Task C - Wellfield response modeling
After the saltwater interface has been modeled and the sentinel wells have been sited, a
three-dimensional MODFLOW (McDonald and Harbaugh, 1988) model of the East wellfield
area will be developed. The objectives of this model are to:
· Evaluate the water level response to alternative pumping rates and configurations of the
East Well Field
· Develop a response plan that can be implemented to reduce saltwater intrusion if water
level and/or quality thresholds are met in the sentinel wells
Model development
The model grid, aquifer properties, and boundary conditions will be based upon data
collected in Task A.
Model calibration
The model will be calibrated to pumpage rates and water levels obtained from the City of
Boynton Beach (and other sources). A sensitivity analysis will be performed upon the
calibrated model.
Predictive simulations
The calibrated model ~ be used to run predictive simulations designed to represent likely
future East Well Field pumpage scenarios anticipated by the City.
Wellfield optimization
water :level.
DelJ
The
~be
included.
Task. O - Well Installation
Borehole Drilling
Mor, itoring wells will be drilled at the locations identified in Task B. The mud-rotary
technique dill be used while drilling in unconsolidated sediment, air rotary drilling dill be
used ~ to obtain representative water quality: samples while drilling. The
boreholes drilled to a nominal 12 inches in diameter to allow for the installation of
borehole.
Well Construction
The new monitoring wells will be constructed so that multiple sampling points are
completed in one borehole. This will provide cost savings to the City of Boynton Beach in
two areas: the initial, drilling costs, and subsequent sampling costs. Since 3 smaller-dmmeter
sampling wells can be completed in a larger borehole, only one borehole need be drilled at
each site. Longer-term, the close proximity of the sampling points eliminates time that
would otherwise be spent moving from site to site, unloading eqUipment, etc.
Depending upon the lithology and data needs, up to 3, 2-inch diameter monitoring wells
can be completed in each borehole. The deepest monitoring well is installed first, and the
annular space is filled with gravel until the screened interval is covered. A layer of sand is
laced on top of the gravel, then bentonite is. placed on toP. of the sand to provide, an.
P ~ ' · · ' · ' then re eated ~or additional
effective sealbetween the litholognc layers. This process m p ~
monitoring intervals. A single, shallow well will be installed adjacent to the well clusters to
monitor the water table surface.
This construction method presents several advantages in that it:
· Reduces the drilling costs by the number of monitoring wells are installed in each
borehole
· Allows for the measurement of vertical gradients between lithologic units
Data Collection
Water level and lithologic data will be colleCted during the drilling process. Following the
completion of the wells, they will be added to the City's monthly sampling routine. These
data will be used in the development of the numeric ~low model.
Deliverable
The Task D deliverable will consist of a brief well completion report that includes as-built
diagrams, field notes, and any field data' collected.
Assumptions
The following assumptions are included in the description of Task D:
· CH2M HILL has been requested by the City to serve as the contracting agent for drilling
services.
Because of the uncertainties with drilling costs, this task will be completed on a time and
materials basis. Our cost estimate includes drilling fees of $60,000. The actual cost will
vary and will be a directly billed expense item.
CH2M HILL will prepare letter specifications for the monitoring well drilling and
construction
· CH2M HILL will provide services during construction (SDC) and RO
· The City will pay any permitting fees associated with well construction.
Task E - Uodel refinement (optional)
Additional data will be collected during and after the installation of the sentinel wells.
Some of these data may necessitate a refinement of either the cross-sectional or optimization
_m_.o..del:, ~For e..x,)m, ple;w, ell e.o. ns.tru.¢tion may identify a previously unknown impermeable
tour. mtemauve~y, aata collected after the wells are constructed may indicate unexpected
water level or quality behavior. In either event, refinement of one or both of the models
may be warranted. This task has been established to cover this eventuality.
Task F - ASR Well Operation Uodeling
A three-dimensional MODFLOW model of the upper Floridan Aquifer for the East WTP site
will be developed. Data f~om the original ASR well construction, current ASR operating
data and anticipated operation of a multi-well ASR system will be used to develop the
model. The objectives of this model are to:
· Evaluate the water level response and well interference associated with different ASR
layout configurations, and
· Develop an ASR system configuration that will maximize recovery efficiency of a multi-
well ASR system, and
· Identify and ~e any potential negative impacts a multi-well ASR system may
have on pumping heads.
Model development
and boundary conditions will be based upon data
Model calibration
The model will be calibrated to ASR pumpage rates and water levels obtained ~om .tt}e City
of Boynt°n Beach. A sensitivity analysis will be performed upon the calibrated model.
Predictive simulations
The calibrated model will be used to run predictive simulations designed to represent likely
multi-well ASR system pumpage scenarios anticipated by the City.
ASR
will then be analyzed by MODMAN (Greenwald, 1998) to
determine the optimum well spacing and pumping rates based on pre-determined criteria.
Multi-Well ASR System Configuration
The results of the MODMAN simulations will be used t° develop a multi-well ASR system
confi~afion. ~ ASR system configuration will spe.ci~, we. lls. epar.a..tion, .,dist,anecoes a~,d
individual ASR Well operating capacities that will maxmuze the benelit or me avt~ weus to
the City.
Deliverable
The deliverable for this task will consist of a brief report that documents the MODFLOW
model development and the MODMAN analysis. The ASR system configuration will also
be included.
TASK G. ASR Well(s) Preliminary Design and Well Construction Permitting
CH2M HILL will provide professional serVices for the preliminary design and permitting
for the construction of an additional 10 mgd of ASR well Capacity. Construction permits
will be required from both the FDEP and PBCHD. A detailed description of the individual
subtasks to be performed is provided below.
Comprehensive Well Inventory
CH2M HILL will conduct a detailed review of eXisting permitted groundwater uses in the
vicinity (1-mile radiUS) of the East W-TP site, based on well inventories of public records on
file with the SFWMD Well Construction and Water Use Permitting 'departments, the Florida
Bureau of Geology, the United States Geological Survey (USGS), and Palm Beach County.
This task will focus on meeting the requirements of the FDEP Class V permit application.
Preliminary Well Design and Site Planning
CH2M HILL will prepare a preliminary ASR well system design that will include the
conceptual design of an ASR well system. This preliminary design will be used for the
initial FDEP Underground Injection Control (UIC) permitting. A conceptual design (block
schematic) of the wellhead, pump(s), and other surface appurtenances will also be included.
I_t is assumed that the ASR well(s) will be located at the East WTP site. The exact location of
the proposed ASR Well(s) will be reviewed and will be chosen with consideration of the
groundwater modeling results from Task F. Additional factors that will be considered in
the ASR well system configuration will include the following factors:
- Optimal location considering existing facilities and operations (i.e., construction site
constraints, and proximity to WTP pumping facilities and piping)
- _FDEP Class V construction and testing requirements
- ~ite accessibility to drilling equipment for the construction of ASR well(s)
Cost Estimate
CH2M HILL will provide an order-of-magnitude cost estimate for the proposed ASR well(s)
facilities. Those facilities will include the ASR well(s), wellhead piping, instnm~entation,
controls, and yard piping.
Preparation of the FDEP UIC Class V Permit Application
This subtask includes preparing the FDEP UIC Class V ASR construction permit application
and responding to up to two (2) requests for additional information.
to five meetings are included in this task as follows:
Pre-application meeting with the West Palm Beach FDEP TAC. The purpose of this
meeting is to obtain consensus from the regulatory agencies regarding the proposed
project and to obtain specific information regarding considerations for the Class V ASR
construction permit application. Up to two additional follow-up meetings are included
in the scope if needed.
Meeting with City staff. A meeting with City staff will be held related to the Class V
permitting process and: the preliminary design of the ASR well system. This meeting
will occur prior to the submittal of the draft FDEP permit application, or as otherwise
required.
FDEP UIC Public Meeting. CH2M HILL will attend one public meeting as part of UIC
permitting process.
Four (4) copies of the FDEP UIC Class V construction permit applications will be provided
to the City for the appropriate signatures. It is assumed that all application permitting and
processing fees will be paid by the City. The current cost of a FDEP Class V well
construction permit is $750. It is assumed that the City will pay this fee directly and it is not
included in this scope of services.
Preparation of the PBCHD Class V Permit Application
and responding to upto two
two
Assumptions
The following assumptions were made in the preparation of this Task Order:
· The City will provide the Consultant with all available wellfield and ASR well
pumpage, water quality, and water level data.
Schedule
Deliverable
Kickoff Meeting
Summary of data collected,
selection of saltwater interface
modeling code
Modeling of saltwater interface
MODFLOW model of East wellfield,
development of wellfield response
plan
Well installation
Model refinement
ASR Well Modeling
ASR Preli:minary Design/Permit
Application
Task A
Task A
Associated Task
Task B
Task C
Task D
Task F
Task G
Time from Notice to Proceed
2 weeks
4 weeks
8 weeks
16 weeks
30 weeks
6'weeks
16 weeks
Compensation
Compensation by the City to the Consultant will be on a lump sum basis in accordance with
the Agreement between the City of Boynton Beach and CH2M HILL with the exception of
Task D. Due to the uncertainties associated with the drillir~g costs, the expenses associated
with this task will be reimbursed by the City on a direct cost basis. It is anticipated that the
drilling costs should be approximately $60,000, however, this cost may vary. The table
below summarizes the proposed cost on a per-task basis. This price shall be modified only
if the scope of work is changed.
Task: Description Labor costs Direct costs Total
A: Data co lection $ 11,200 $ 975 $ 12,175
B: Saltwater interface $ 22,200 $ 2,050 $ 24,250
model
C: East we Ifield $ 30,650 $ 2,800 $ 33,450
optimization
D: Well: Installation $ 13,800 $ 1,235 $ 15,035
D: Well Construction $ $ 60,000 $ 60,000
E: Model refinement $ $ $ 0
F: ASR Modeling $ 10,600 $ 925 $ 11
G: ASR Preliminary $ 30,050 $ 2,650
Design/Permit App. $ 32,700
TOTAL $ 118,550 $ 70,630 $ 189,180
References
CH2 HILL, 1992. Estimated Safe Yield Study. Prepared for the City of Boynton Beach.
Greenwald, R.M., 1998. MODMAN: An Optimization Module for MODFLOW. HSI Geotrans:
Freehold, N.J.
McDonald, M.G., and Harbaugh, A.W., 1988. A Modular Three-Dimensional Finite-
Difference Ground-Water Flow Model. United States Geologic Survey: Reston, VA.
APPROVED BY
By:
Gerald Broening, Mayor
Dated:
day of ~
0
2001
SUBMITTED BY
CH2M HILL, Inc.
Thomas M. Mc~ormilk, P.G., Vice President
Dated:
2001