CHAPTER 9
Water and Wastewater System
Introduction
There are three major water and sewer providers within the city limits and
extraterritorial jurisdiction of Harlingen. The main provider of both sewer and
water and is Harlingen Waterworks. A secondary water provider is East Rio
Hondo Water Supply Corporation providing water mostly north and east of the
city limits. The third water supplier and second sewer provider is Military
Highway Water Supply Corporation. They provide services primarily south of
the city limits and within the city limits strip extending south along FM509. A
map of the three major provider service areas is included. Figure 9-1 illustrates
water service areas (often referred to as areas of Certification of Convenience and
Necessity or CCN). Figure 9-2 illustrates wastewater service areas.
Harlingen Waterworks
The Harlingen Waterworks System (HWWS) is a division of the City of
Harlingen. The system operates under a general manager with a Board of
Trustees appointed by the City Commission of Harlingen.
HWWS provides potable water service to customers within the City's water
certificated area, which is established by the Certificate of Convenience and
Necessity (CCN) issued to HWWS by the Texas Natural Resources Conservation
Commission (TNRCC). HWWS also sells treated water to wholesale customers,
which include the City of Combes, the Town of Palm Valley, the City of
Primera, the East Rio Hondo and Military Highway Water Supply Corporations
and emergency water to La Feria and San Benito.
HWWS provides sanitary sewer service to areas within the sewer certificated
area, which is established by the CCN issued to HWWS by TNRCC and sewage
treatment for Combes and Primera. While the majority of the area within the
existing City Limits of Harlingen is presently served by the City's sewer system,
much of the area to the west of the city does not currently have municipal sewer
service although development partnerships between developers and HWWS are
expanding sewer to this area rapidly.
HWWS must adhere to the Federal and State laws and regulations governing
water and wastewater utilities in the State of Texas. As regulations change,
HWWS must continue to make changes in the system to provide a safe drinking
water supply and to clean the wastewater in order to protect the waters of the
State of Texas.
Raw Water Source
The City of Harlingen has one source of water to supply the needs of the
community and the customers it serves. As with all entities in the area, Harlingen
obtains its raw water supply from the Rio Grande River. Water is transmitted to
Harlingen through canals of the Harlingen Irrigation District.
Water Rights
Under Texas law, a municipality or other user is allowed to use water based on
the amount of water rights that it owns. Once the annual water rights allotment
has been used, a user cannot use additional water without purchasing or leasing
from other users' water rights.
Harlingen currently has a total allocation of 21,338 acre-feet of water rights per
year. While transporting this water from the Rio Grande through canals, pipelines
and reservoirs, 15 percent of the use is charged to the City to account for water
losses in the system. Therefore, the net amount available for use by the City is
18,137 acre feet per year, which is an approximate average of 16 million gallons
per day. In 2000, the amount of raw water billed to the City was an average of
14.9 million gallons per day (mgd) or 78.1 percent of the available water rights.
Wholesale customers served by the system must provide their own water rights
for their use.
Raw Water Storage Reservoirs
The raw water is delivered to the storage reservoirs at each of the two water
treatment plants in Harlingen. The reservoirs provide several benefits to the City,
which include providing an emergency supply of water, taking water when water
quality is best, and storage of water when there is no charge to the City's water
rights allocation (free pumping).
At the Downtown Treatment Plant, the reservoir (known as City Lake) has a total
storage capacity of 30 million gallons or 92 acre-feet. The Downtown Treatment
Plant was expanded in early 2001 to 20 mgd. At this rate the reservoir would
provide approximately 1.5 days storage without additional inflow from the canal.
The other plant, M.F. Runnion Water Treatment Plant, has a reservoir with a
capacity of 295 million gallons or 905 acre-feet. At a treatment plant capacity of
20 mgd, this equals approximately fourteen days of storage.
Safe Drinking Water Act
The Safe Drinking Water Act (PL 93-523) was enacted by the U.S. congress in
1974. As a result of this act, the United States Environmental Protection Agency
(USEPA) promulgated the National Primary Drinking Water Regulations
(NPDWRs).
Subsequently, Congress passed the 1986 Amendments to the Safe Drinking
Water Act. These amendments directed the USEPA to add an additional 83
contaminants to the list of regulated compounds by 1989, and 25 additional
contaminants every three (3) years thereafter. The USEPA has responded to this
directive by promulgating a number of new drinking water regulations and is in
the process of preparing additional rules.
Water Treatment Plants
HWWS operates two water treatment plants in Harlingen. The Downtown Plant,
located near the center of the City, was originally constructed in 1928, by Central
Power and Light Company (CPL). In 1945, HWWS purchased the water system
from CPL. Major improvements have been made in 1952, 1956, 1988 and 20002001. The capacity of the Downtown Water Treatment Plant will be 20 mgd by
the end of the year 2001.
The M.F. Runnion Water Treatment Plant, located on Dixieland Road in the
southwest portion of the city, was originally constructed in 1972. In 1988, the
Runnion plant was expanded to its current capacity of 20 mgd.
A water treatment plant should be sized to meet the system's maximum day
demand. In 2000, the maximum day demand occurred in July, when the
Downtown Treatment Plant treated 6.3 million gallons and the M.F. Runnion
Plant treated 17.8 million gallons. The combined total of 24.1 million gallons
equals to 89 percent of the system's total 27 mgd treatment capacity or 60 percent
of the total 40 mgd capacity when the Downtown expansion is complete in 2001.
The Downtown Water Plant expansion should provide sufficient capacity
through year 2015 assuming current growth rates prevail.
Water Treatment Processes
Raw water storage, described previously, assists in settling of sediment contained
in the raw water delivered to the reservoirs, with added benefits of oxidation and
sunlight. Storage can also cause the growth of algae and other organisms, which
affect the taste, odor and color of the water. Aeration is used to strip the gases
and organics from the raw water prior to treatment. Copper sulfate is also used to
control the growth of algae in storage reservoirs during the summer months.
M.F. Runnion Water Treatment Plant
Chemical addition and rapid mixing are provided to introduce chemicals used for
settling in subsequent processes. Typical chemicals include the use of polymers
and aluminum sulfate (alum). The rapid mixer provides agitation to completely
introduce the chemicals to the incoming raw water.
The water then goes through a gentle mixing zone to allow the particles to
coagulate or join together prior to settling in reactor type clarifiers. The clarified
water is then sent to dual media filtration consisting of sand and anthracite. This
process is required to achieve a turbidity of less than 0.5 nephelometer turbidity
units (ntu).
The finished water is then stored in underground storage tanks, prior to pumping
into the distribution system through a high service pumping station.
Other treatment includes the disinfection of the water throughout the plant. This
process may include chlorine, ammonia, and/or chlorine dioxide. Caution is
exercised in the disinfection process to avoid creation of trihalomethanes
(THM's) when chlorine is added to the water. THM's are formed by chemical
reaction between organics and chlorine. The use of ammonia helps to prevent this
reaction. Powdered activated carbon, fed in a liquid slurry, is used in the process
to improve the taste and reduce odor in the water.
Downtown Water Treatment Plant
Raw water storage for the Downtown Plant is the same as the M.F. Runnion
storage except it does not use aeration. Raw water is pumped through a static
mixer that mixes the chemicals added. These chemicals include aluminum sulfate
(alum), and permanganate. The raw water then flows to two ActiFlo, patented
water treatment units each rated at 10 mgd. These are the first treatment units of
their kind in the state of Texas. These treatment units combine the alum floc with
a polymer and sand to create a sand ballasted floc with enhanced settling
properties. Mixing chambers develop the attachment of sand to the floc. The flow
then goes through a settling basin and tube settlers.
Flows after the settling basin are treated with chlorine dioxide, powdered
activated carbon for taste and odor control and are chlorinated. The chlorinated
water is then filtered and stored in underground storage tanks. A high service
pump station then pumps the stored water to the distribution system.
Both treatment plants have emergency generators for use in the event of power
outages.
Water Transmission and Distribution System
The water distribution system consists of water mains and lines constructed of a
variety of materials including cast iron, asbestos cement, PVC, and concrete steel
cylinder. These pipelines range from 4 inches to 30 inches in diameter. The
locations of major distribution lines and tanks as well as proposed improvements
are shown in Figure 9-3.The distribution system has three elevated storage tanks
and two surface storage tanks with high service pumps. The elevated tanks ride
on and maintain distribution pressure. The two surface storage tanks have
pumping facilities to bolster pressure and have approximately two-day storage
under emergency conditions. The Treasure Hills surface storage tank has an
emergency generator for use in the event of a power outage. This 10 million
gallon tank can provide water for the hospital and residences on the south side of
the Arroyo in the event of a major catastrophe that separates the water systems on
the north and south sides of the Arroyo. The surface storage tanks and their
pumping stations equalize the pressure gradients of the distribution system.
Water System Plan
A detailed water system plan for HWWS was prepared in 1984, entitled "Water
System Analysis" by Kindle, Stone & Associates, Inc. HWWS has since made
modifications due to changing development. This section of the Vision 2020
Comprehensive Plan Chapter has been updated by HWWS and utilizes previous
studies and in-house studies to summarize the needs of HWWS and extrapolate
current projections from previous findings.
Table 9-1
EXISTING ELEVATED STORAGE FACILITIES
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Location
Capacity (mg)
High Water Level
(msl)
Low Water Level
(msl)
Pendleton Park
1.25
171.7
127.5
North Loop
1.50
171.0
129.5
Port of Harlingen
0.3
171.7
141.7
Treasure Hills Blvd.*
10.0
Pumps Maintain System Pressure
Rio Hondo Road
10.0
Pumps Maintain Sytem Pressure
* The Treasure Hills Tank has an emergency generator.
Projected Water Demand
HWWS's certificated area for water service is unique with respect to the city
limits and the comprehensive planning study area. The Waterworks' certificated
area extends beyond the city limits to the west of the Harlingen (including the old
Stuart Place system). The certificated area is smaller than the planning study
area. Other portions of the study area not served by HWWS are certificated for
water service by other entities.
Assumptions were made to correlate the population projection for areas served
by HWWS. The projections of water demands used to determine future planning
are shown in Table 9-2.
Table 9-2
PROJECTED AVERAGE DAILY WATER DEMAND
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Average
Wholesale
Daily
Customers
Consumption
Connections
Population Per Capita
(Tbl 2-3B Demand
Units:
Meters
Persons
gal/cap/day MGD
MGD
MGD
1995
----
53,547
170
9.10
1.2
10.76
2000
20,499
62,500
*171
10.70
1.2
11.90
2005
21,102
64,337
**175
11.26
1.5
13.32
2015
24,735
75,412
**190
14.33
1.9
16.95
2020
26,902
82,018
*198
16.24
2.3
19.35
Year
Total
Demand
* Includes rural population with water service.
** Source: Harlingen Waterworks System
Future Water Supply Needs
For the year 2000, HWWS was billed for 16,667 acre-feet of water. This
accounts to 78 percent of the total acre-feet of water rights available, which are
21,338 acre-feet. The Rio Grande River supplies the water used in Harlingen.
This source of water is shared by many locations along the U.S./Mexico Border
region including Mexico.
For many years, concerns regarding the amount of water available as well as the
water quality have been raised. In the spring of 1995, the Water Master for the
TNRCC, issued warnings to users of the Rio Grande that the reservoir level in
Falcon Lake were very low and urging water conservation until the reservoir
level increased. As the area grows, so does the demand for water. As part of the
recommended update to HWWS's water system plan, consideration should be
given to alternative sources of water. These could include use of brackish ground
water resources in the area, water conservation measures, wastewater recycling
and reuse, and capturing excess irrigation and runoff water released to the
Laguna Madre. HWWS should continue to acquire additional water rights to
increase the City's water supply and serve future demands of the Harlingen area.
Water Treatment Requirements
A water treatment plant should be sized to treat the maximum day demand in any
given year. For the year 2000, data reveals a 10 percent distribution loss. Using a
1.75 peak day to average day ratio and a distribution of 10%, the required
treatment capacities for HWWS are shown in Table 9-3.
An expansion of the Downtown plant will increase the combined capacity to 40
mgd. According to HWWS records, in July 2000, the combined output from both
plants was 24.1 mgd or 89.2 percent of the 27 mgd capacity.
HWWS is in construction to increase the capacity of the Downtown Water
Treatment Plant to 20 mgd by constructing two mgd ActiFlo units and
constructing two new filters.
Water Distribution System Improvement Needs
HWWS has made substantial improvements to the water distribution system over
the past decade. Major "looped" or interconnected transmission mains have been
constructed around Loop 499 as well as in the Industrial Air Park on the east side
of the city. Transmission mains have been installed to serve the areas west of the
city.
Table 9-3
PROJECTED WATER TREATMENT CAPACITIES
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Year
(A) Average
(B) Dist. Loss
Metered
Factor
(mgd)
(C) Demand
Factor
(D)
Treatment
Capacity
(mgd)
(E) Capacity
1995
10.76
.132
1.75
22.63
27
2000
11.82
.10
1.75
23.57
40
2005
13.32
.10
1.75
29.85
50
2015
16.95
.10
1.75
34.17
60
2020
19.35
.10
1.75
39.01
60
Required Capacity D=[A/(1-B)]xc
Source: Harlingen Waterworks System
To maintain adequate pressures in the remaining portions of the service area,
HWWS should extend and interconnect the transmission lines on the west side of
the city. As Harlingen continues to grow into this area, additional improvements
will be needed to maintain service to these outlying areas. Figure 9-3 indicates
the location of existing and proposed major transmission lines as well as lines
down to 12" size required to meet the expected growth in these areas.
Treated Water Storage Requirements
The purpose of storage in a distribution system is to provide equalization of
treatment. In addition to equalization, storage is also needed for fire flow
demands.
Storage allows the water plants to operate at a constant rate during the day. Plants
should be capable of treating the maximum day demand. The storage allows the
system to supplement the instantaneous demand when it is greater than the
treatment capacity, and is replenished when the instantaneous demand is less than
the capacity of the plants. For needed fire flow demands, storage provides the
additional water quantity and pressure required for emergency fire fighting
situations. Surface storage of two (2) ten million gallon tanks allows for
approximately two days of emergency water if treatment is not available or major
line breaks interrupt supply.
Ground Storage Requirements
Ground storage requirements are governed by requirements established by the
TNRCC. Additionally, the Texas State Board of Insurance historically has
included water storage in its determination of the city?s "key rate" for fire
insurance purposes. While these insurance guidelines are not mandatory for
sizing water storage facilities, they affect property insurance rates for water
system customers. The State Board of Insurance has recently contracted with an
outside source for its rate setting functions, which makes the key rating system
now obsolete. The new method used to set insurance rates is the Insurance
Services Office Public Protection Classification (ISO PPC) system, which does
not have a direct correlation of required storage to population. Under the ISO
PPC system, water storage is now evaluated on a case-by-case basis. In addition,
elevated storage is often beneficial for the reduction of distribution main size by
increasing water pressure in the distribution system. The projected future ground
storage requirements for HWWS are shown in Table 9-4. Based on the State
Board of Insurance requirements, no additional ground storage will be required.
With this storage, additional ground storage facilities are not expected to be
required to serve the projected needs to the year 2020.
Table 9-4
GROUND STORAGE RECOMMENDATIONS
(Million Gallons)
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Location
Existing
2005
2015
2020
Downtown
Treatment Plant
2.5
2.5
2.5
2.5
M.F. Runnion
Treatment Plant
7.0
7.0
7.0
7.0
Treasure Hills
Storage Tank
0.0
0.0
0.0
0.0
Rio Hondo Rd.
Storage Tank
0.0
0.0
0.0
0.0
F.M. 800 Storage
Tank
0.0
0.0
0.0
0.0
Total Storage
9.5
9.5
9.5
9.5
TNRCC Total
Storage
Requirement (1)
2.0
2.1
2.5
2.7
Insurance
Guildeline (2)
8.1
8.4
9.8
10.7
(1) Requires a total of 100 gallons per connection of ground storage.
(2) State Board of Insurance Key Rate requires 130 gallons per person per day. Includes service area outside the city limits.
Elevated Storage Requirements
Elevated storage requirements for HWWS, in accordance with the TNRCC
requirements and fire insurance guidelines, are shown in Table 9-5. The State
Board of Insurance required the Waterworks to have elevated storage or
groundwater surface storage equal with emergency generators for pumping up to
130 gallons per person for a 10 hour period (or 55 gallons per person per day).
The TNRCC requirement is 100 gallons of elevated storage or surface tank
storage provided the surface tank storage has auxiliary power for pumping.
Table 9-5
ELEVATED STORAGE RECOMMENDATIONS
(Million Gallons)
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Location
Existing
2005
2015
2020
Pendleton Park
1.25
1.25
1.25
1.25
N. Loop 499
1.50
1.50
1.50
1.50
Port of Harlingen 0.30
0.3
0.3
0.3
Treasure Hills
1.5
1.5
1.5
------
FM 800
------
-------
0.5
0.5
Total
3.05
4.5
5.05
5.05
TNRCC
Requirement (1)
1.7
2.0
2.3
2.5
Insurance
Guideline (2)
3.0
3.7
4.3
4.7
(1) Required a total of 100 gallons per connection of elevated or surface storage tank with auxiliary power for pumping
(2) State Board of Insurance requires 55 gallons per capita of elevated storage
Wastewater System
HWWS provides sewer service to nearly 58,000 residents within the city limits
of Harlingen. Most areas outside the city limits but within the sewer certificated
area, are not currently served by HWWS. The existing service area is shown in
Figure 9-2. Areas that are Harlingen's wholesale water customers are not
currently served by HWWS sewer system. There are no sewer facilities in the
surrounding towns and unincorporated areas except for the Town of Palm Valley
and City of San Benito. These municipalities both have their own wastewater
treatment and collection systems. The towns of Combes and Primera have
constructed sewer collection systems which tie to a common lift station and force
main. The force main is constructed to Harlingen's Wastewater Treatment Plant
#2.
Harlingen's wastewater flows consist of normal domestic wastewater along with
commercial and industrial discharges to the sewer system. HWWS requires
industrial customers to pre-treat their wastewater to at least domestic strength
wastewater before discharging into the City's sewer system. This requirement
allows the treatment of wastewater at the City's two treatment plants to maintain
a more consistent effluent quality.
The service areas and wastewater treatment plants are shown in Figure 9-4. An
area near the center of the city can be diverted to either HWWS plant via the
Cleveland Street Diversion Structure.
The City's sewer system was evaluated in 1992, by Camp Dresser & McKee, Inc.
(CDM) as described in the report entitled "Wastewater Collection System Master
Plan." This report summarizes information from previous studies and evaluates
HWWS sewerage needs to the year 2010.
Wastewater Collection System
The existing HWWS wastewater collection system consists of a total of 77 lift
stations and approximately 214 miles of gravity sewer and force mains ranging in
diameter from 6-inch to 16-inch. Sixty percent of the collection system is
constructed of vitrified clay pipe with the remaining lines constructed of PVC.
Construction of sewer mains in the area can be difficult due to the presence of a
high ground water table. The flat terrain causes the construction of gravity sewers
for long main lines to require deep excavation. The shallow ground water table in
the area makes the construction of deep sewer mains cost prohibitive. Therefore,
the use of lift stations and force mains is required to convey the wastewater to the
treatment plants.
The locations of the lift stations are shown on Figure 9-4. Of the 77 total lift
stations, 57 are submersible pump type. The remaining are the wet/dry pit and
self priming pump type . These lift stations and force mains operate
intermittently. Long detention times in the system cause the wastewater to
become septic prior to arriving at the treatment plants. This septic condition
creates hydrogen sulfide gases, which are the major source of odors in the
system.HWWS currently has two wastewater treatment facilities in its system.
Wastewater Treatment Plant No. 1
HWWS currently has two wastewater treatment facilities in its system.
Wastewater Treatment Plant No. 1 is located on the north bank of the Arroyo
Colorado, south of the intersection of Commerce Street and Business U.S. 77.
The plant was constructed in 1951, with a capacity of 3.1 mgd and is permitted at
that capacity today.
In 1985, the plant was modified from a trickling filter plant to a combined
trickling filter and activated sludge plant. The plant was originally designed to
split the flow, with 1.0 mgd flowing through the trickling filters and 2.1 mgd
flowing through the new activated sludge units. The trickling filters are no longer
in service and all flow is treated in the activated sludge units, with desirable
results. In 2003 the Waterworks plans to convert the trickling filters to activated
sludge which should increase capacity to approximately 6.0 mgd.
Wastewater Treatment Plant No. 2
Wastewater Treatment Plant No. 2 is located on the north bank of the Arroyo
Colorado south of FM 106 and east of Loop 499. This plant was constructed in
1960, with a capacity of 3.5 mgd. This plant was originally constructed as a
trickling filter plant and was upgraded to a two-stage trickling filter plant in
1981.
In 1990, major changes and modifications were constructed at Treatment Plant
No. 2. What was known as the original plant was modified to a trickling
filter/solids contact plant and tertiary filter to consistently meet effluent
standards. In 1997 additional major changes were accomplished at the plant. The
trickling filters were changed to activated sludge and the plant capacity was
increased to 6.2 mgd. In the future, increases in capacity can be accomplished by
adding an additional final clarifier and an additional chlorine contact basin.
Additional filters were added to produce a good reverse osmosis feedwater.
Currently, HWWS delivers over 3.0 mgd of a 4.0 mgd capacity of "bottle
quality" water from wastewater effluent, to a major industry adjacent to the
treatment facility (Fruit of the Loom). By reusing the wastewater in lieu of the
City's potable water system this "one of a kind" facility saves HWWS the water
rights required to serve this industry.
After the industry uses the process water, it is returned to a separate section
(Section C) of Treatment Plant No. 2, which consists of an activated aeration
treatment system. This section of the plant is designed to treat 5.5 mgd of
industrial waste combined with 0.5 mgd of municipal wastewater. The treated
effluent is discharged into the Arroyo Colorado.
HWWS has constructed the largest supercritical water oxidation process in the
world and the first unit in the world to process wastewater sludge. The process
has been designed to treat the sludges from both wastewater plants, septage from
area septage haulers and restaurant grease trap waste. This process is very
environmentally friendly and will not utilize landfill space for sludges. Inert
solids will be disposed of on permitted property. The sludge process has capacity
for additional sludge treatment, which should provide for demand until
approximately 2010.
Wastewater Flows
The analysis of the wastewater flows performed for HWWS indicated the flow
characteristics shown in Table 9-6. Minimum, average and maximum day flows
for dry weather are shown, as well as the maximum wet weather flow and the
maximum monthly average day flow. These characteristics are important
considerations in projecting wastewater treatment needs.
The average rainfall in Harlingen is 26 inches per year. During periods of heavy
rainfall, water inflows into the sewer system cause the flows into the plant to
increase. The amount of inflow into the City's sewer system has decreased over
the past 10 years due to improvements made in the collection system.
Recent flow data for the two wastewater treatment plants indicates somewhat
different information than the flow characteristics described in the 1992 CDM
report. The flows for calendar year 2000, as measured by HWWS, are shown in
Table 9-7. The maximum monthly average flow in 2000 was 7.91 mgd.
Table 9-6
WASTEWATER FLOWS
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Flow Type
Total Flow (mgd)
Factor (gpcd)
Minimum Dry Weather
4.4
74
Average DryWeather
5.22
88
Maximum Dry Weather
5.62
95
Maximum Wet Weather
11.69
197
Maximum Monthly Average
8.27
139
SOURCE: Harlingen Waterworks System
The higher maximum monthly average flow shown in HWWS recent flow
information is reflecting the amount of potable water that is used to supply
additional process water to the industry as a substitute for recycled effluent.
These flows can be as high as two mgd. When potable water is used by the
industry, that water is added to the original wastewater flows generated within
the City. When the
Table 9-7
1994 WASTEWATER FLOWS
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Month
Plant No. 1 (mgd) Plant No.2 (mgd)
Total (mgd)
January
1.943
3.280
5.223
February
1.910
4.120
6.030
March
2.230
4.460
6.690
April
2.725
3.860
6.585
May
2.662
3.090
5.752
June
2.618
3.200
5.818
July
2.541
3.300
5.841
August
2.767
3.630
6.397
September
2.760
5.150
7.910
October
2.850
3.820
6.670
November
3.069
3.400
6.469
December
2.989
2.720
5.709
Averages
2.587
3.669
6.256
recycling plant is in operation, the effluent flow to the receiving stream is less.
Projected Wastewater Flows
For purposes of projecting required wastewater treatment capacity, a combination
of information from the 1992 CDM report and current population forecasts are
used. By the year 2001, it is expected that HWWS's sewer service area will be
expanded to include the Stuart Place area, as well as Primera and Combes. The
CDM report utilized higher population projections for the comprehensive plan
are used to predict future flows. See Chapter Two for further information on
development of the population projections.
Wastewater Plant Sizing
A wastewater treatment plant should be able to adequately treat the maximum
monthly average flow per day expected. This accounts for inflow and infiltration
during wet weather and any other seasonal variations in flows. The plant should
also be able to treat daily peak demands. Harlingen experiences a slight increase
in flows due to the influx of winter tourists between the months of November
through March. The CDM report indicated that the maximum monthly average
flow in 1990-91 was 5.30 mgd. Based on an estimated population of 52,000, a
flow factor of 102 gallons per person per day was calculated. In the year 2000,
with an estimated service population of 62,500, and a dry weather, monthly flows
were 5.2 mgd. The flow factor is 83 gpcd. This is increased as shown in the table
to project for future plant requirements. The results are indicated in Table 9-8.
Wastewater TreatmentPlant No. 1 Needs
The current plant is rated at 3.1 mgd. However, the trickling filter portion of the
plant has been out of service for the last several years. The activated sludge
addition made to the plant was completed in 1984. This improvement was
designed to treat 2.1 of the total 3.1 mgd capacity. The trickling filter plant is
being designed to be converted to an activated sludge plant and increase its
capacity to 6.0 mgd. This will suffice until the year 2010.
Due to the demand placed on Plant No. 2 for the reuse of wastewater effluent, the
common area served by both plants is generally diverted to Plant No. 2.
Table 9-8
MAXIMUM MONTHLY AVERAGE FLOW PROJECTIONS
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Year
Population
(Tbl 2-3B)
Stuart
Place
Area
Total
Primera
Combes
Population
Population Population
Served
Flow
Factor
(gpcd)
Total Dry
Weather
Flow
1995
*52,000
2,700
2,600
2,600
*52,000
102
5.30
2000
59,400
3,100
3,000
3,000
*62,500
83.2
5.20
2005
64,337
3,800
3,700
3,700
75,537
85
6.40
2015
75,412
4,500
4,300
4,300
88,512
90
8.00
2020
82,018
4,900
4,700
4,700
96,318
95
9.20
* Population served by the wastewater system is less than that served by the water system; Primera and Combes are not currently
served. Service is expected by the end of 2001.
Wastewater Treatment Plant No. 2 Needs
Wastewater Treatment Plant No. 2 is expected to provide for the future needs of
the City. This plant not only provides for thetreatment needs of the City, it also
provides the use of recycled water for industry. This is expected to continue into
the future with the area?s finite water resources.
By the year 2020, the capacity of Plant No. 2 is projected to be 9.0 mgd. Not
included in this figure is the sizing requirement of the reuse treatment area within
the plant. HWWS has completed an updating of the existing treatment plant
using a cost effective reuse of existing basins conversion to activated sludge. The
plant is designed to meet more stringent stream standards recently imposed for
the plant's discharge permit. These requirements include a 10 BOD, 15 TSS and
3 NH3.
Currently, Treatment Plant No. 2 has the capacity to treat approximately 4.0 mgd
of "bottle water quality" effluent to provide process water for industry with the
use of reverse osmosis treatment. To provide this amount of effluent for reuse,
approximately 5.3 mgd of wastewater must be treated. The remaining 1.3 mgd
(brine) is discharged into the treatment plant. A project is under construction to
pipe treated water from WWTP#1 to WWTP#2 to increase the amount of water
available to be treated by the reverse osmosis system.
Wastewater Collection System Needs
The wastewater collection system service area is expected to expand to the west
of the City and include wholesale service to the Cities of Primera and Combes. A
Texas Water Development Grant has funded sewer collection systems for
Combes and Primera and a force main along the northern boundary of the City to
Wastewater Plant #2.
The existing collection system was modeled under future flow conditions by the
CDM report. Several of these lines have been reworked by HWWS personnel to
remove deficiencies. As indicated in Table 9-9, a total of 10,310 feet of sewer
lines were identified as having insufficient capacity to accommodate the
projected wastewater flows for 2010 conditions. Based on the population
projections of this comprehensive plan, CDM?s 2010 projections would
approximate this plan's 2020 flows.
Table 9-9
FUTURE COLLECTION SYSTEM DEFICIENCIES
Harlingen's Vision 2020 Comprehensive Plan
Harlingen, Texas
Location
Diameter (in.)
Length (ft.)
1. From L.S. #9 to New
Hampshire St. in New
Hampshire to Hale Ave.
15
4,170
2. In Hale Ave. from Falcon
St. to Ed Carey Dr. to
Missouri Pacific Railroad.
15
3,790
18
230
12
2,120
3. In alley between Haine
Drive and 23rd St. from
Treasure Hills Blvd. to
Clifford Dr. and then to L.S.
#5
TOTAL
10,310
SOURCE: Wastewater Collection System Master Plan, Camp Dresser & McKee, Inc., March 1992. Revised by Harlingen
Waterworks System, April 2001.
East Rio Hondo Water Supply Corporation
East Rio Hondo Water Supply Corporation (ERHWSC) is the second of three
main water and sewer providers within the Harlingen extraterritorial jurisdiction.
It was established in 1979 after the consolidation of two groups of rural citizens
of Cameron County, Texas. The goal of all citizens involved was to obtain
potable water service for the rural community. Each group started separately, one
in the area north of Harlingen with 150 customers, and the other north, east and
south of Rio Hondo with 1,000 customers. Each applied separately to the
Department of Agriculture, Farmers Home Division for Utilities (FmHA) for
funding to establish their potable water system. FmHA recommended
consolidation of the two groups, and in 1979 provided grant and low interest loan
funding to establish the East and West system. Construction of the two
distribution systems and a 1.6 mgd plant was begun in 1980. The north Harlingen
area was established as the West system and initially the sole source of water was
a wholesale water meter with HWWS. The East system was served by the 1.6
mgd plant.
With time, the system has grown from 1,150 meters in 1982 when service started,
to over 4,900 in 2001. ERHWSC provides wholesale water to Military Highway
Water Supply Corporation (MHWSC), Indian Lake, the United States
Immigration and Naturalization Service (INS) Detention Center, and has
interlocal agreements for emergency wholesale water to Arroyo Water Supply
Corporation, and the City of Los Fresnos.
Administration
ERHWSC is a non-profit member-owned corporation, established for the
development of potable water in rural areas. Every customer with a meter is a
member and part owner of ERHWSC. The system operates under a general
manager with a Board of Directors, elected by members from nine separate
districts within the Corporation's certificate of convenience and necessity (CCN)
boundaries shown in Figure 9-1. The board meets at 7:30 p.m., on the first
Monday of every month, excluding holidays. The agenda is posted as required by
the Texas Open Meetings Act.
ERHWSC is developing a set subdivision and line extension ordinance, which
will be approved by the Board of Directors. This ordinance with the oversight of
the system personnel determines the requirements for subdivisions and line
extensions. Any variances from the ordinance or system personnel decisions may
be appealed to the Board of Directors at their general meeting during public
comments.
Water System
ERHWSC has over 400 miles of pipe in its distribution system, ranging in size
from 2" to 14" (See Figure 9-3) . The original water plant, located one half mile
south of FM1561 on Nelson Road, now services the entire distribution system.
The plant was expanded to 3.2 mgd in 1997. Raw water for the plant is diverted
from a Resaca supplied with Rio Grande River water by a Cameron County
Irrigation district Number 2 (CCID#2). The source of raw water is a pump station
on the Rio Grande River near Los Indios. The surface water treatment plant uses
conventional coagulation, flocculation, sedimentation, filtration, and disinfection
prior to storage and pumping to the distribution system.
HWWS supplements the north Harlingen area with wholesale potable water
through a master meter. The West system was connected to the East system in
May 2000, and the supplemental water from HWWS is used only during times of
lower pressure. The 1978 contract between ERHWSC and HWWS was originally
for 3,000,000 gallons per month (gpm). The contract was amended in 1984 to
6,000,000 gpm. Any amount over the 6,000,000 gallons is charged at a higher
rate as overage with an additional impact fee.
ERHWSC has three elevated water towers in the distribution system and a
ground storage tank at the water treatment plant. The towers are located as
follows:
(1) 0.1 miles west of Briggs Coleman Road on the north side of FM 508 (250,000
gallons)
(2) 1.2 miles east of FM 803 on the north side of FM 106 (200,000 gallons)
(3) 0.2 miles west of FM 1575 on the north side of FM 510 (300,000 gallons)
The ground storage tank at the water plant has a capacity of 416,000 gallons for a
total system capacity of 1,166,000 gallons.
Water Rights
ERHWSC currently owns 718.898 acre-feet of domestic-municipal-industrial
water rights, leases 485 acre-feet, and utilizes 250 acre-feet from a wholesale
customer. The Corporation is currently establishing a new 50-year lease contract
with CCID#2 for 1,000 acre-feet per year. ERHWSC is also purchasing an
additional 1,158.5 acre-feet in 2001 to produce a total available surface water
right of 3,612.398 acre-feet of water per year. The maximum amount of water
rights used by ERHWSC was at 2,502 acre-feet in 2000. ERHWSC will have
approximately 1,110 acre-feet of water rights for future growth.
Future Improvements
Future improvements planned include the additional of a new 8.0 mgd surface
water treatment plant west of Laureles on FM 510, a new 1,000,000 gallon
ground storage tank at the existing plant on Nelson Road, a new 1,000,000 gallon
ground storage tank and pumping station near the INS Detention Center, and new
larger distribution lines on FM 510, FM 803, FM 1847 and Stanford Road.
As development continues, additional water towers or ground storage pumping
stations will have to be strategically located and constructed. Long-range
planning includes the potential to build an additional water treatment plant in the
North Harlingen area with expanded storage and distribution capacity in that area
as well.
Sanitary Sewer System
ERHWSC has established a CCN for sanitary sewer service (see Figure 9-2) and
is pursuing colonia funding from the United States Department, Rural Utilities
Services, Rural Development. ERHWSC plans to build a sanitary sewer
treatment plant near Lozano and provide service to Lozano, Las Yescas, La Tina,
and surrounding colonia communities. At this time, the plant and collection
system are under design.
Military Highway Water Supply Corporation
The Military Highway Water Supply Corporation (MHWSC) is the third major
water and sewer provider within the Harlingen extraterritorial jurisdiction. It is a
member-owned, non-profit corporation incorporated pursuant to the Texas Water
Code Chapter 67, Non-Profit Water Supply or Sewer Service Corporation and as
supplemented by the Texas Non-Profit Corporation Act, Tex. Rev. Civ. Stat.
Ann., art 1396-01, et seq (West 1980, Vernon Suppl 1996 as amended) for the
purpose of furnishing water and wastewater utility service. Corporation operating
policies, rates, tariffs, and regulations are adopted by the Board of Directors who
are elected by the members of the Corporation.
History
MHWSC provides water service to all the communities and rural areas found
along U.S. Highway 281 (Old Military Highway) from the western city limits of
the City of Brownsville to the eastern city limits of the City of Pharr (see CCN
figure 9-1). Presently, MHWSC supplies water to approximately 7,275 customers
in its service areas. The original water system was designed approximately
twenty-seven (27) years ago in 1973 to serve less than twenty-eight percent
(28%) of the present customers. An expansion to the system was made in 1981
and improvements to the system were completed in 1985, 1993, 1995 and 1999.
The major source of supply to the original MHWSC system in Cameron County
was the City of Harlingen Waterworks system which supplies a maximum of 600
gpm to a hydro-pneumatic plant located at FM1479 and FM 800. By 1993, the
Cameron County service area, which depended on the City of Harlingen for
water, required 1,500 gpm. To provide adequate water supply to customers in
Cameron County, four wells were developed and used as a raw water source for a
Water Treatment Plant built in Las Rusias. Distribution system improvements
were also made to meet pressure and quantity requirements for families in the
Cameron County service area. The hydro-pneumatic booster station using City of
Harlingen water is still in place to supplement the water treatment plant.
The Del Mar Heights area consists of a small community east of the City of Los
Fresnos and is provided water metered direct from the ERHWSC distribution
system using their water storage and pressure.
Presently, MHWSC has plans to expand the existing Las Rusias Water Treatment
Plant in Cameron County to double its present capacity. MHWSC submitted a
complete federal assistance application to Rural Development - Rural Utilities
Service in November 2000 requesting financial assistance for doubling present
water treatment plant design capacity.
Conditions of Existing Facilities
The conditions of the existing facilities in each area have been evaluated to
determine the suitability for continued use and compliance status with state
requirements. In order for a water system to meet Texas Natural Resource
Conservation Commission requirements, the supply must provide a minimum of
0.6 gallons per minute of water for each customer served. The plants must have a
minimum of 200 gallons of water storage for each customer served and maintain
the operating pressure for the distribution system. The pressure maintenance
must be a minimum of 20 gallons per customer in pressure tank capacity and
booster pumps with a total capacity of two gallons per minute per customer or
elevated storage with gravity flow. The distribution system lines must be large
enough to provide the required flow of water at a minimum pressure of 35 PSI to
each customer at a flow of 1.5 gallons per minute per customer.
Cameron County Area
The Cameron County area of the system serves 3,956 families with distribution
piping in sizes from 16" down to 2" (See Figure 9-3). Supply for the Cameron
County area is furnished by four (4) deep wells located in Los Indios and water
purchased by a water purchase contract with the HWWS. The maximum delivery
rate provided by the water purchase contract is 600 gallons per minute while the
production rate provided by each of the four (4) deep wells is 375 gallons per
minute. The area has a capacity of 2,100 gallons per minute or 3,500 meter
capacity, based on TNRCC criteria. The four (4) deep wells supply water to the
water treatment plant located just east of the intersection of U.S. Highway 281
and FM 1479 in the Colonias of Las Rusias. The treatment plant can also treat
surface water from the Rio Grande River. MHWSC owns close to 800 acre-feet
of water rights that are diverted through the Harlingen Irrigation District. A 10"
supply line from the HWWS runs south approximately 20,000 feet to a hydropneumatic plant located at the intersection of Rangerville Road (FM1479) and
FM 800. This 10" line provides the 600 gpm supply.
Storage is provided by a 150,000 gallon ground storage tank at hydro-pneumatic
plant, a 1.0 million gallon clear well at the water treatment plant, and seven
100,000 gallon elevated tanks. These elevated tanks are located throughout
southern Cameron County. The locations are as follows:
1.) On FM 800 1/8 mile west of FM 2520 (FM800 Tank),
2.) On FM 1479 ½ mile north of US 281 (Rangerville Tank),
3.) Located along U.S. Highway 281 ½ mile each of FM 1577 (Ranchito Tank)
4.) In the community of La Paloma,
5.) In the community of San Pedro,
6.) In the community of Lago
7.) In the community of Santa Maria. The storage capacity is 1,850,000 gallons,
or 9,250 meter storage capacity based on TNRCC criteria.
Pressure is maintained by five (5) booster pumps totaling 5,000 gpm at the water
treatment plant and two (2) service pumps rated at 700 gpm at the hydropneumatic plant, which supply the seven (7) elevated tanks with flow of 6,700
gpm. The South Hidalgo County System can supplement this system through a
valved interconnection at the county line.
The system serving this area is presently being operated using only the water
treatment facility. The hydro-pneumatic plant is being maintained with water
purchased from HWWS as an option in case of an emergency. When the water
treatment plant booster pumps are not pumping, the distribution requirement of
35 PSI minimum pressure is maintained from the seven (7) elevated tanks.
Del Mar Heights Area
The Del Mark heights area serves 59 families with distribution piping in sizes
from 4" to 2". Supply and pressure is provided by a water purchase contract with
ERHWSC.
Wastewater System
Figure 9-2 shows the MHWSC sewer CCN area. MHWSC provides sewer
service to families in its service area. In the early part of the 1980's, the first
sewerage system was planned to serve the community of Progreso. This
sewerage system was put in operation in 1989 and served approximately 370
families. In the last seven years MHWSC has expanded its Central Sewerage
Collection System to include most of the communities in its service area.
Presently MHWSC provides sewer service to approximately 2,740 families in
Cameron and Hidalgo Counties.
MHWSC presently operates the following wastewater collection and treatment
systems within their service area:
1. Progreso - Progreso Lakes
2. Las Rusias - Los Indios
3. San Pedro - Villa Nueva
4. Santa Maria - Bluetown
5. La Paloma - El Ranchito
6. South Alamo ******
South Alamo collection system and wastewater treatment plant are presently
under construction and will be completed by the end of 2001.
Condition of Existing Facilities
All facilities except the original Progreso Collection Wastewater Collection
system were completed within the last five (5) years and are in good condition.
Some manholes on the original Progreso System are in need of repair due to gas
corrosion. The conditions of all existing facilities were evaluated to determine the
suitability for continued use and compliance status with TNRCC.
All existing gravity flow lines, force mains, lift stations and wastewater treatment
plants are adequately sized and suitable for continued use with the exception of
La Paloma Wastewater Treatment Plant. Wastewater generated by families living
in the community of Palmer and the growth rate being experienced surrounding
the communities of La Palona and El Ranchito due to a booming economy in the
Rio Grande Valley has caused the wastewater treatment facility to exceed the
design capacity of 210,000 gpd or 2,100 persons/525 families. Presently, La
Paloma Wastewater Treatment Plan is treating wastewater generated by
approximately 712 families. Based on TNRCC design criteria, a wastewater
treatment facility treating the waste generated by a population of 2,848 requires
the following design capacity:
2,848 persons x 100 = 284,000 gpd
Presently, La Paloma Wastewater Treatment Plan exceeds design capacity by
74,800 gpd or 748 persons or 187 families. Presently, MHWSC has plans to
construct a new wastewater treatment in Cameron County. MHWSC submitted a
complete federal assistance application to Rural Development - Rural Utilities
Service in November 2000 requesting financial assistance for a 510,000 gpd
wastewater treatment plant on Joines Road to insure provision of adequate sewer
service in the areas south of the City of San Benito.
Strive for Ongoing Quality Service
Goal 9.1 Continue to build partnerships and encourage mutually beneficial
cooperation between systems in order to better provide for the development
needs of the region.
Goal 9.2 Continue to monitor water and wastewater needs based on
population growth and plan ahead to provide adequately for such
population.