Project Name:Aquifer Storage and Recovery \ Texas Water Development Board
Project

Basin: Not Applicable
Sub-watershed Description: Not Applicable
Lead Entity: City of Laredo Water Utilities Department
Other Participants: Texas Water Development Board, CH2Mhill, City of Laredo
Engineering Department Environmental Division

Funding Source: TWDB grant + city match
Amount of Funding: $287,500.00
Project Start Year: 4/17/95
Project Finish Year: On going

Contact: Jerry Pinzon, P.E.
         Brent Christian, P.G.
         Asst. Director, Water Utilities Hydrogelogist
         402 Bartlett
Environmental Engineering Division
          Laredo, TX  78041                             City of Laredo
          tel: (956) 795-2600                           1110 Houston St.
          fax: (956) 795-2605                           Laredo, Texas 78042
          gpinzon@compuhardt.net                        Tel: (956)791-7358

Abstract: The Aquifer Storage and Recovery (ASR) project is intended to
determine if surface water, collected during the rainy season from the Rio
Grande River, can be stored in the shallow Laredo formation for use during times
of higher demand or during drought demand.

The City of Laredo obtains raw water for treatment from Reach IV of the Middle
Rio Grande River , which flows along the southwestern edge of the City.
Historic average and maximum treated water demands have increased over the last
35 years.  The ave rage day demand has been increasing by 0.8 million gallons a
day (mgd) per year and maximum day by 1.3 mgd per year.  Projections indicate
that the average raw water demand will exceed the City's current water rights
allocation by the year 2005.

Demand patterns indicate water demands are highest during the period from May
through September, Peaking in July.  Low demand season typically occurs during
the period from mid October through April.  The average raw water demands are
less than the t reated maximum day demand s indacating the need to either
increase the raw water pumpage during maximum day demand periods, or rely on
storage.  Because the City's system does not have raw water storage capacity,
frequent changes in raw water pumping rates appear to be required.  An ASR
system or other large volume reservoir system could serve to significantly
reduce the variability of these pumping rates over the course of a season.
The existing watersystem could utilize ASR capacity to help meet peak demands
from continued growth.  If ASR is shown to be feasible through testing, this
application could postpone or eliminate the need to construct an additional
water treatment pla nt.

The project was developed into four stages:
 1) charactize the quality of the groundwater within the Laredo area;
 2) drill and install test wells within close proximity of major water
    distribution sites;
 3) test the wells by performing pumping test in order to determine the
    hydraulic character of the aquifer;
 4) perform injection tests in order to determine the recoverable quantity and
    quality of the injected water.

The first phase of the project was to characterize the water quality in the
Laredo area.  The Texas Water Development Board and the City of Laredo
Engineering Department Environmental Division's personnel collected groundwater
samples from selected l ocations in and around the Laredo area and from various
points along the City's distribution points.  The samples were collected in
order to evaluate the geochemical characteristics of the groundwater and the
interaction that would occur between the City's water with the formation water
and with the formation itself.

The second phase of the project included drill test wells at points within the
City that are close to to the City's water distribution system.  The wells were
electronically logged after drilling in order to determine the most advantageous
area of th e formation to complete the wells.  Soil samples were collected
during the boring of the well in order to detrmine the physical
characteristeristics of the formation and for field and laboratory analysis.

The third phase of the project was intended to determine the quantity of water
that could be withdrawn from the aquifer.  Pumping tests were conducted on each
well in order to estimate the tranmissivity and where possible the storativity
of the aquifer.

An aquifer recharge test is planned as the fourth phase of the project.  This
test will be used to determine how much water can be stored and then produced
from the formation.

Progress to Date: The project is entering into the fourth phase of testing.

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