Type
of Project. The City of
San Benito, Texas is proposing a three-part improvement project to the existing
water and wastewater system.
The first
component of this project is the construction of a new water treatment plant
(WTP) that would increase the Citys capacity from 5.97 million gallons per day
(MGD) to 10.0 MGD. Construction of the
new WTP would follow a phased-in approach.
During the first phase till Year 2015, the WTP would have an operational
capacity of 6.0 MGD. After this time,
the new WTP would be expanded to the full 10.0 MGD capacity.
The
second component of this project is to expand the Citys accessible elevated water storage. The City is currently served by two elevated
storage facilities: the 500,000 gallon Jefferson St. water tower and the
750,000 gallon Williams Rd. water tower.
Because of a design flaw with these towers, the City cannot access the
full 1.25 million gallons (MG) of storage.
The new elevated storage tank will be for 1 MG. A 16-inch transmission
line would lead from the new 10.0 MGD WTP to the Citys existing 1.5 MG ground
storage tanks and high service pump station located at the existing 5.97 MGD
WTP; another 16-inch line from the new 10.0 MGD WTP would link with the new
overhead storage tank.
The third component involves phasing-in of the WWTP.
The first phase, lasting till Year 2015, would construct a new 2.5 MGD
WWTP. At the beginning of the second
phase, the new WWTP would be expanded to 3.5 MGD.
It
is anticipated that these improvements will meet projected demand for the City
till Year 2025.
Location of Project. The City of
San Benito, Texas is located in Cameron County on U.S. Hwy 77, approximately
two miles south of Harlingen, Texas in the lower Rio Grande Valley region. The new WTP will be sited on a twenty acre
parcel of land west of the City, adjacent to the Resaca De Los Fresnos. The new elevated tank will be in the
Citys southernmost section. The
existing WWTP is located north of the City on the Arroyo Colorado. The project is located within the
100-kilometer border region as defined by the La Paz agreement. The 2000 population has been estimated at 27,686. The project considers a total project
population of 43,477 by the year 2030.
The City has a water consumption of 126 gallons per capita per day
(gpcd) average.
Description of Project and Tasks. The
new WTP will be sited on a twenty acre parcel of land that will be purchased by
the City from the San Benito Industrial Foundation. Construction of the new WTP will involve a phased-in
approach. The first project phase will
construct a new 6.0 MGD WTP at a new location.
The operational capacity of the existing WTP would be reduced to 4.0 MGD
and operated in tandem with the new WTP till 2015 when the existing plant would
be decommission and the new plant expanded to 10.0 MGD. The new WTP would receive raw water from the
Resaca De Los Fresnos from raw water pumps.
In preparation for construction of the new 1 MG
elevated storage tank, the existing Jefferson St. tank will be
decommissioned. The new water tower
will be relocated from the existing site.
Because the overflow elevation of the Jefferson St. tower is 27 feet
below the Williams Rd. tower, only 30% of the capacity of the Williams Rd. tank
can be used. The city can only access 725,000 gallons of their elevated storage
capacity without overfilling the Jefferson St. tank. As part of improvements to the Citys water distribution system,
one 16-inch transmission line would lead from the new 10.0 WTP to the Citys
the existing 1.5 MG ground storage tanks and high service pump station located
at the existing WTP (these pumps and tanks will remain in service at its
present located after existing WTP is decommissioned), and another 16-inch line
from the new 10.0 WTP to the new overhead storage tank.
Construction
of the new WWTP will, like the WTP, involve a phased-in approach. The first phase, lasting till 2015, will
construct a new 2.5 MGD mechanical aeration WWTP next to the existing lagoon
system. It is the intent of the City to operate the lagoons in tandem with the
new WWTP during peak flow periods. It
is anticipated that the existing lagoons will treat up to 1.5 MGD. At the beginning of the second phase, the
new WWTP would be expanded to 3.5 MGD, providing a total of 5.0 MGD of
treatment capacity.
Compliance with International Treaties and
Agreements. This project complies with the agreements
that the United States and Mexico have signed, such as the La Paz Agreement,
Border Environmental Comprehensive Plan, Border XXI Program and the North
American Free Trade Agreement.
II. Human Health and the
Environment
Human Health/Environmental Needs. Construction of a new WTP,
overhead storage facility, WWTP, and related distribution improvements will
address several human health and environmental issues for the residents within
San Benitos water treatment and wastewater treatment service area. Population increases have resulted in the
WTP exceeding maximum permitted treatment capacity, with a resulting TNRCC
issuance of an Enforcement Order. An
EPA Administrative Order for violation of permitted treatment parameters for
BOD and TSS has been issued for the WWTP.
Design flaws in the existing elevated water storage facilities, not yet cited by the TNRCC,
does place the City in violation of TNRCC minimum elevated storage
standards.
WTP
operation at or above allowable capacity levels increases the possibility of
contaminates, particularly pathogens, reaching treated water for public use and
consumption. Not meeting storage
requirements is a health concern due to lack of pressure at peak flow
levels. Inadequacies with existing
storage facilities poses a safety concern for fire flow usage. When released from the WWTP into the Citys
receiving stream, the high BOD levels become a potential hazard to water and
local habitat.
Environmental Assessment. An
Environmental Information Document (EID) has been prepared for the City of San
Benito Water and Wastewater Improvements Project. The EID attempts to satisfy the requirements of the BECC and
Environmental Protection Agency (EPA).
Currently, EPA is reviewing the EID. The FONSI will be issued early
August, 2002.
Compliance with Applicable Environmental and Cultural
Resource Laws and Regulations. As part of the preparation of the EID, comments were
solicited from relevant Federal, State, and Local agencies including: the Texas
Archeological Research Laboratory, the Texas Historical Commission, the US Fish
and Wildlife Service, Texas Parks and Wildlife Department, Federal Emergency
Management Agency, the United States Army Corps of Engineers, and the Cameron
County Engineers Office. Project
approval responses were obtained from all agencies contacted. The project is in compliance with all
applicable environmental and cultural resource laws and regulations, including
among others: Significant, Unique or Important Farmlands, National Natural
Landmarks, Wilderness Protection, Wild and Scenic Rivers, Wetlands Protection,
Floodplain Management, Fish and Wildlife Protection, Endangered Species
Protection, Historical, Architectural, Archeological, and Cultural Sites, Air
Quality, and Environmental Justice.
Appropriate
Technology. The existing
WTP utilizes standard water treatment processes including coagulation,
sedimentation, clarification, filtration, and chlorination. The proposed project is the construction of
a 10.0 MGD WTP designed to treat water taken from the Resaca De Los
Fresnos.
Cameron
County Irrigation District No. 2, by way of a canal and resaca system, supplies
raw water for the City of San Benito from the Rio Grande River. The Citys delivery point is at the WTP. Raw water is drawn from six pumps to the
first part of the treatment train, coagulation.
Coagulation. This process uses chemicals to catalyze the
aggregation of particulate matter in the raw water. The larger particles that develop settle better and are removed
more completely. It is important for
coagulation that there be rapid mixing of the chemical coagulant. The second part of the coagulation phase is
flocculation. Flocculation occurs when
the particles reach a size that the main method of increasing precipitate size is
by trapping other particles in their matrix.
Pilot
studies will determine the best process for coagulating the influent water to
the plant. The Preliminary Engineering
Report for this Project mentions the use of conventional coagulation, used by
the City currently. Newer technologies,
specifically membrane treatment and synthetic coagulant computer controlled
technology (e.g. Microfloc) are already in use by some of the providers in the
area with good results. These
technologies will be the primary focus of the pilot study.
Sedimentation.
Sedimentation removes the
flocs created during coagulation. The
process is based on the non-turbulent steady flow through a series of canals
allowing the flocs to naturally settle out and collect on the bottom of the
sedimentation basin.
Design
of settling basins is based on the overflow rate. Sedimentation basins may have a rectangular shape with length
being several times longer than width or circular design with radial flow from
the inside to the outside. The system
will be designed so that there are several settling basins in parallel,
allowing for maximum flexibility and redundancy.
Filtration. The filtration process polishes the water by
removing the remaining flocs using granular material, usually sand. Filters are differentiated by the rate of
filtration they allow. Slow sand
filters are the older technology. Rapid
sand filters often dependent on chemical pre-treatment of water before filtering. Rapid sand filter beds tend to be smaller
and shallower than slow sand filters.
Another
trend in filtration, which may be considered in the design of the San Benito
WTP, concerns use of dual media.
Multiple media are being used increasingly to attain the greater
chemical removal standards required under recent regulations. The usual alternate media are anthracite or
activated carbon.
If
a synthetic coagulate process is used, the coagulation and filtration processes
will be combined into one factory made module.
There is not a sedimentation process with this type of treatment. Rather the floc is embedded in the media and
must be periodically washed out.
Backwash timing is critical for a good final product, so a computer is
used to monitor the module for head increase as the filters become occluded.
Disinfection.
Disinfection involves the
killing or inactivation of pathogens which previous parts of the treatment
process did not remove from the effluent (water). The oxidants used in
disinfection include chlorine gas, chloramine, chlorine dioxide, ozone, or
ultraviolet light. The final method of
disinfection will be decided after the pilot studies. The decision on what chemicals to use is also dependent on the
contaminants in the water, ease of operation, and costs.
A
composite type storage tank should be utilized, considering the large amount of
storage water to be contained.
Construction of the support pedestal section will utilize reinforced
concrete, providing durability, low maintenance, and eliminating costs for
painting. The storage tank will be
comprised of welded structural steel.
The
existing WWTP is a non-mechanical lagoon and pond system consisting of primary,
secondary, and final treatment.
Wastewater enters the system from a 16-inch outfall line from San Benito
to the South. Primary treatment occurs
in three facultative lagoons, followed by a secondary treatment which takes
place in three stabilization ponds.
Resulting effluent is sent to a transfer lift station to continue treatment
or be recycled through primary and secondary treatment or into the
stabilization pond that feeds the hyacinth basins. Final treatment consists of fourteen hyacinth ponds. WWTP outfall line releases to an un-named
ditch, which feeds into the Arroyo Colorado.
The
proposed WWTP would involve the construction of an extended aeration system
adjacent to the existing WWTP. The treatment process for this alternative is a
single aeration basin followed by a single clarifier. Utilization of a mechanical aerator system will increase the
level of oxygen in the wastewater, enhancing aerobic digestion. The water separated from the sludge is
brought to another basin where filters then remove any remaining solids. Finally, disinfection reduces harmful
pathogens. Ultraviolet (UV) light
disinfection has been chosen for this step.
Multiple mercury vapor arc lamps are either submerged or placed
overhead, from which UV rays are able to destroy pathogens.
This
single train system is permissible because the existing lagoon process gives
redundancy. Sludge from sedimentation
will be thickened, digested, and then applied to the digesting beds. A shared waste train will connect the two systems.
The
exact treatment process will be determined during the preliminary engineering
phase of the Project, and will be some form of the extended aeration
process.
O&M
Plan. The engineer will be responsible for the development
of an Operation and Maintenance Manual.
This O&M Manual will be completed prior to completion of
construction. All personnel will
receive training prior to the start up of WTP and WWTP Manuals. Mr. Albert Cabrera oversees all operations
at both facilities. He has WTP and WWTP
licensing and over 20 years of experience.
Initial startup of the system will include testing of the components
prior to acceptance by the owner to assure that they properly perform their
intended function. If there are new
procedures used in WTP or WWTP operation, the company providing the equipment
will be required to conduct training on site for City staff in operating and
maintaining the new equipment.
Compliance
with applicable design norms and regulations.
The TNRCC has regulatory
authority for water and wastewater treatment plants in the State of Texas. The TNRCC will also have review authority in
the final design of the water distribution and sewer collection lines, which
must meet State Design Criteria.
Additional requirements of the funding agency (BECC) include approval of
the preliminary engineering plan and project cost estimate, approval of plans
and specifications prior to bidding, approval of procurement methods, site
inspections during construction, approval of amendments and change orders
during the project, and approval of the close out documents. There will be close coordination between the
City, BECC, and other involved agencies to assure these procurement requires
are met.
IV. Financial Feasibility and Project Management
Financial
Feasibility. The
financial analysis determined the following funding structure of the project
and the user rates to guarantee the financial sustainability of the operating
agency.
|
Current Water and sewer Expenses (Annual) |
|||
|
Concept |
Amount (US$) |
||
|
|
Operating Revenue (Water and Sewer) Operating Expenses (Water and Sewer) Non-operating Expenses (Water and Sewer) |
2,504,428 2,413,465 37,713 |
|
|
|
|
Net Income |
$
53,250 |
|
Estimated Cost |
|||
|
Concept |
Amount (US$) |
||
|
|
|
Water Treatment Plant |
18,069,852 |
|
|
|
Elevated storage tank Wastewater Treatment Plant |
3,861,447 10,512,936 |
|
|
|
Total |
$32,444,235 |
Rate
Model: The rate model was developed
by NADB.
|
SINGLE
FAMILY RATES (US$) |
|||
|
|
2003 |
2004 |
2005 |
|
Average
Monthly Water Bill |
$18.01 |
$21.26 |
$24.66 |
|
Average
Monthly Sewer Bill |
$15.50 |
$16.42 |
$17.41 |
|
Total
Bill |
$33.51 |
$37.68 |
$42.07 |
|
|
2006 |
2007 |
2008 |
|
Average
Monthly Water Bill |
$28.60 |
$30.03 |
$31.54 |
|
Average
Monthly Sewer Bill |
$18.46 |
$19.57 |
$20.54 |
|
Total
Bill |
$47.06 |
$49.60 |
$52.08 |
|
Source |
Amount (US$) |
% |
|
TWDB (loan) |
17,533,351 |
54 |
|
NADB-BEIF Construction Assistance (grant) |
14,910,884 |
46 |
|
Total |
$32,444,235 |
100% |
In
addition, the NADB is proposing Transitional Assistance in the amount of $2,999,341.00 to reduce the overall impact increased debt service payments on
the city of San Benito ratepayers caused by the construction of the project.
Project
Management. The City has adequate personnel to handle
the proposed infrastructure and to respond to any potential emergency that
might arise during operation and maintenance of the project.
Comprehensive
Public Participation Plan. The
public participation plan of the City of San Benito and the Wastewater Project
Steering Committee submitted their plan on January 17, 2002 and was approved that same day.
Steering Committee: The steering committee is
composed of Pete Claudio, Chair; Celeste Sanchez, San Benito School District;
Lynnete Ross, citizen; Bill Weekly, businessman; Rick Torres, Valley
Interfaith; Romero Garza, Housing Authority; Mario Medrano, Health Care
Professional; Matilde Martinez and Irma Rodriguez, of the San Benito Parental
Involvement Program; Leroy Gomez; book store owner; Nelda Agado, Parent
Educator; Sam Mendez, Educator; Beatriz Rodriguez, Valley Interfaith; Ursulo
Robles, businessman; Pat Barber, citizen; Velma de los Santos, VIP Realty;
Robert Cepeda, Public Health Department; Bill Elliott, Valley Baptist Medical
Center; and Mary Bolado of Dr. Bolados office. The technical work group
developed in support of the committee is composed of: Victor Treviño and Martha
McClain of the City of San Benito; Carlos Mondragón, consultant; and Tom Brown
consulting engineer.
Local Organizations: Local organizations contacted include: St. Theresa Church Group;
Chamber of Commerce; Kiwanis Club; San Benito Literacy Center; Parental
Involvement Meeting; San Benito Ministers; Fred Booth Elementary PTA; Resaca
City Civic; Friends of the Library/Library Board; Lions Club; Housing Authority
Residents; Landrum Elementary PTA; and Sullivan Elementary PTA.
Public
Information: Project information,
such as the Facility Plan and draft Step II Document were available for public
review at City Hall and the local library 30 days prior to the first public
meeting. A fact sheet was developed and distributed to local residents and
available at the public meetings. Newspaper and television coverage of the
project has taken place.
Public Meetings: Public meetings were held
on February 21, June 25 and July 23,
2002. An average of 180 people attended each meeting. Exist surveys show more
than 90 per cent support for the project and the rates.
Definition
and Principles. The project
complies with BECCs definition of Sustainable Development: Conservation
oriented social and economic development that emphasizes the protection and
sustainable use of resources, while addressing both current and future needs,
and present and future impacts of human actions. This project is to improve the quality and safety of water and
sewer service for the Public Works customers of San Benito. The existing
WTP has been cited by the TNRCC for exceeding its rated capacity. This is a serious problem since the City
cannot meet current peak day demands.
When the plant produces more water than its rated capacity there is the
potential that the water has not been sufficiently filtered to remove harmful
pathogens. Satisfaction of water
quality goals will have significant
long-term benefits to all users of this resource.
The
existing elevated storage capacity of 725,000 gallons yields approximately 112
gallons of elevated capacity per connection.
This does not meet the minimum capacity requirement of the TNRCC for
elevated storage. This lack of
sufficient elevated storage capacity is a safety problem because the City water
system cannot provide adequate pressure during peak flow periods, such as fire
protection. Increasing the Citys
storage capacity takes into account future development and population growth.
The
Citys WWTP has been cited by the TNRCC for peak flows of over 75% capacity for
three consecutive months in 1997. In
May 2001, the EPA issued an Administrative Order against the City for violation
of BOD and TSS standards from June to January 2000. The City has had problems with keeping the hyacinth basins filled
with hyacinths for many years. Current
wastewater flows have exceeded the plants capacity at peak flow. The inability of the Citys WWTP to
adequately treat its wastewater is a serious health problem. Discharge of inadequately treated effluent
to the Arroyo Colorado will continue to contribute to the degradation of water
quality, posing a danger to public health.
Satisfaction of water quality goals will have significant long-term
benefits to all users of this resource.
The construction of the new wastewater treatment system will provide
treatment capacity that will be able to provide existing and future customers
of the system with a safe, high quality, dependable, wastewater collection,
treatment, and disposal.
Institutional and Human Capacity Building. The
project will be managed by the local sponsor and will be constructed and
operated in conformance with the requirements of both the regulatory and
funding agencies. The process used in
the development of this project has followed a planning and public participation
process that has developed alternatives and associated costs, solicited public
input into the process, established priorities based on the input of the
stakeholders and proceeded according to the priorities established in the
planning process.
Conformance
with Applicable Local/Regional Conservation and Development Plans.
The construction contractor will be required to
observe State and Federal Safety Laws during construction of the
improvements. The Contractor will be required
to provide a written safety plan. Each
project component will be quality tested prior to acceptance by the owner. The owner and his construction engineer must
also accept the entire project as completed to their satisfaction before the
contractor can receive his final payment.
Once construction is completed the City is required by TNRCC to have
safety plans developed for the handling of all hazardous materials. The City will also implement the American
Water Associations safety plan as part of their safety program and continue to
promote a safe work environment.
A
pollution protection plan will be required of the contractor before he
commences work.
There
are closure and post closure requirements by the TNRCC for existing and new
WTPs and WWTPs.
The
project is in conformance with the Water and Wastewater Facility plan developed
by the city in 2000 and with the Regional Water Plan approved by TWDB. The city
has also a Drought Contingency Plan.
Natural
Resource Conservation. The City does have a TWDB approved formalized water
conservation plan.
Community Development. The development of a
new WTP, elevated storage facility, and WWTP will provide sufficient capacity
to meet the water needs of the Citys customers for the next 25-30 years. With sufficient wastewater treatment
capacity, the city will be able to manage growth within its available
resources, while providing an affordable water supply and wastewater service to
customers.