1GUIDANCE DOCUMENTS
William Feathergail Wilson, PG 21

20012 PCCD
RULES
MITIGATION PLAN
MANAGEMENT PLANDROUGHT PLAN

2

The map depicts the surface expression of the major aquifers in the PCCD area.


Leona Gravel: stippled yellow
Alluvial: light yellow
Wilcox: light tan
Carrizo: light orange

A deep potential aquifer does come to the surface and is known as the Lower
Trinity or Hosston Formation. This potential aquifer parallels the Hays-Caldwell
County boundary.

GROUNDWATER PRINCIPLES

3Groundwater is intimately associated with surface water via recharge anddischarge into and out of the subsurface.
Two types of groundwater are recognized:
 Unconfined Confined

An aquitard is relatively impervious clay that retards vertical groundwater flow.
An aquitard is not present above an unconfined aquifer.
The Leona Gravel and the Alluvial sands along the PCCD streams are examples of
unconfined aquifers. The Wilcox and Carrizo are both confined and unconfined
depending upon their location.

4

5

Groundwater along the Plum Creek watershed is both a losing and gaining stream
dependent upon the surface geology and topography. For example, the Leona
Gravel is topographically higher than Plum Creek and Leona springs feed into thePlum Creek. As Plum Creek crosses the Wilcox outcrop, it loses water into theunderlying sands.
A pumping well creates a drawdown cone of depression.

6
As the well continues to pump, the cone of depression spreads out to a greater
distance.

7This figure shows a drawdown radius of 1,500 feet from a pumping well after 5days of production at a rate of 150 gallons per minute (GPM). The drawdown isshown at varying distances out to 3,000 feet. Calculations can be made by varying
the input parameters.
For example, suppose you own 50-acres and you drill a permitted well on the edge
or corner of your property. Utilizing this figure you would be draining groundwaterfrom your property as well as your neighbor’s property. The 2011 State of Texas
Legislative session passed SB-332, which states you own the groundwater beneathyour property. PCCD can furnish you estimates of the cone of depression fromyour permit request.

If wells are drilled too close to each other, they can interfere with each other andincrease the cone of depression. This figure depicts two wells pumping from a
confined aquifer
GROUNDWATER TERMS

8Acre Foot: is 1-acre of groundwater, 1-foot deep

Hydraulic Conductivity: is a measure of how fast groundwater is moving throughand aquifer on a per unit area expressed by the symbol K.

Transmissivity: is a measure of K times the saturated thickness of the aquifer.
Storage Coefficient: is a unitless number used to calculate the amount ofgroundwater that is stored in the aquifer at any one instant in time in three
dimensions.
 All of these numbers may be derived from pump tests or they may beobtained averages from the GAM’s furnished by the TWDB.

9
 Carrizo-Wilcox GAM averages:o Storage Coefficient = 3.0 E-4
o Transmissivity = 2244 GPD/footAverages are deceptive over large areas. The Storage Coefficient has more averagevalidity when applied to sand and sandstone than the Transmissivity number,which is more site-specific. However, SB-660 enacted in the 2011 State of Texas
82nd Legislative session demands the use of “modeled” numbers for groundwater
management.
If challenged, the burden of proof is set upon the challenger and may involve
considerable expense. At least three monitoring wells would have to be drilled anda formal pump test would have to be initiated.

10

GEOLOGYREPORT
DOCUMENTS

11

GROUDWATER ESTIMATES BENEATH
ACREAGE
William Feathergail Wilson, PG 21
May, 2012

The annual amount of groundwater available beneath a given parcel of property
can be estimated from the following procedures:
 Pump testso Hydraulic conductivity
o Transmissivityo Storage coefficient Estimates of storage coefficients
Storage coefficients in confined aquifers generally range from 1E-3 to 1E-5 andaverage 1E-4. Thus, estimates can be made by assuming 3.0E-4 as a confined orsemi-confined aquifer for a storage coefficient.
These estimates do not take into consideration sustainable recharge. That can be
estimated from annual rainfall and total withdrawal on an annual basis or
expressed as managed available groundwater.
The following equations allow such estimates:

GW  (Sc Rc Aqt Ac)365  acre feet / year
GW: annual available groundwater
Sc: Storage coefficient (3.0E-4)
Rc: Recovery % (0.25)
Aqt:: Saturated aquifer thickness
Ac: Surface acreage12This equation does not consider the radius of influence outside the boundaries ofthe property. An estimate of this can be obtained from an online calculator.

http://www.icalcul8.com/theis.php

This is the average drawdown for 300 acre feet in the Carrizo-Wilcox utilizing
published GAM averages. Note: 300 acre feet is the PCCD rule limit.

13

Modeled parameters may be obtained from the Carrizo-Wilcox GAM or estimatedfrom known pump test information within the Caldwell County Wilcox or Carrizo
areas.
The above analytical method is only applicable to confined aquifer areas. The
Leona gravels and the stream vectored Alluvial aquifers will require higher Sc
numbers such as 1.5E-2 or 1.5E-3 and higher T values since these aquifers are14
unconfined. The same analytical method and equations can be applied to bothconfined and unconfined aquifers.
For the purposes of PCCD rules, estimate tables could be constructed or just place
this method within the rules with simple instructions and average numbers.
Transmissivity is often expressed in other units and conversion factors should be
provided within the rules.
T= 1ft2/min = 1.077 x 104 (GPD/ft)
T=1ft2/day =7.480 (GPD/ft)

The Carrizo-Wilcox Aquifer in Texas
Scott Jones
Spring 2008

15

16

17

GEOLOGY OF BRACKISH WATER
BY
William Feathergail Wilson
Texas PG 21
May, 2012

INTRODUCTION
Brackish water is defined at various levels of Total Dissolved Solids. The mostcommon demarcation is set at > 1,000 parts per million (ppm) or 1,000 mg/liter.
The following table is referenced in the PCCD Rules.

There are no set rules as to TDS classifications. Many Texans drink water that falls
between 500 and 1,000 ppm despite the EPA safe drinking water standard
definition of 500 ppm. Cattle balk at TDS levels above 3,000 ppm.
Brackish and saline water will become increasingly more important to GCDs in thenear future due to the following factors:
 Desalination will become a necessity
 Oil & Gas Injection exempt wells will seek cheaper shallow injection zones
and begin to compete with desalination
 GCD’s will be forced into regulation of brackish water and compete with
TRRC exempt usage for hydrofracing

18
TRCC EXEMPT WATER WELLSt

WATER USE IN ASSOCIATION WITH OIL AND GAS ACTIVITIESREGULATED BY THE RAILROAD COMMISSION OF TEXAS
1. RAILROAD COMMISSION OF TEXAS JURISDICTION
Generally, under Texas Natural Resources Code, Title 3, and Texas Water
Code, Chapters 26 and 27, the Railroad Commission of Texas(Commission) has jurisdiction activities associated with the exploration,
development, or production of oil or gas or geothermal resources, includingtransportation of crude oil or natural gas by pipeline. The Commission also
has jurisdiction over surface mining for coal, uranium, and iron ore gravel.
2. USE OF FRESH WATER IN ASSOCIATION WITH OIL AND GASACTIVITIESWater is used in association with many oil and gas activities, including use(in general order of relative volume) as a supplemental fluid in enhanced
recovery of petroleum resources; during drilling and completion of an oil orgas well; during workover of an oil or gas well; during solution ofunderground salt in brine mining or hydrocarbon storage cavern creation;
as gas plant cooling and boiler water; as hydrostatic test water for pipelines
and tanks; as rig wash water; as coolant for internal combustion engines forrigs, compressors, and other equipment; for sanitary purposes; and forlaboratory purposes.
The largest volume of water is used in enhanced recovery. The following
table indicates injected volumes of total fluids (produced water, fresh
makeup water, and other fluids) relative to estimates of total injectedvolumes of fresh water. Note that the trend for using fresh injection makeup
water is declining. Most fresh water is injected for enhanced recovery in
Commission Districts 8 and 8A in West Texas. The 1996 estimate for fresh
water injected for those two districts was 252 million barrels.
Year

Estimate of
fresh/brackish

Estimate ofproduced

TOTAL
Estimated

19
water (in million
barrels)

water (inmillionbarrels)

Volume of Fluids
injected (inmillion barrels

CY 1998

316

6,000

6,316

CY 1999

276

5,600

5,876

CY 2000

254

5,900

6,154

CY 2001

212

5,900

6,112

The next largest volume of water is used during the drilling and completionof oil and gas wells. Water is used during drilling for drilling fluid preparationand make-up water, for completion fluids, including cementing, in wellstimulation, as rig wash water, as coolant for internal combustion engines;
and for sanitary purposes.
Fresh water is used in oil and gas well stimulation. Stimulation methods
include acidizing and/or fracturing. In order to be able to produce gas atvolumes and rates that are economical, reservoirs with low permeability
must be treated. One method of treatment to increase permeability is
fracture treatment or “fracing.” Conventional fracture technology increases
permeability as a result of pumping frac fluid, which generally consists of aviscous gelled fluid, and which creates an increase in the available surface
area by creating fractures that are “propped up” or held open by thepropping agents in the frac fluid.
Hydraulic fracturing consists of pumping into the formation large volumes offresh water that generally has been treated with a friction reducer,
surfactant and clay stabilizer, and that contains sand. Hydraulic fracturing
maximizes the horizontal length of the fracture while minimizing the vertical
fracture height. The fractures, which are held open by the sand, result inincreased surface area, which further results in increases in the desorptionof the gas from the shale and increases in the mobility of the gas. The
result is lower completion costs and faster recovery of a larger volume of
the gas-in-place. The volumes injected during hydraulic fracturing treatment
can range from 70,000 barrels in a vertical well to over 90,000 barrels in ahorizontal well. Fracing, where necessary, generally takes place
immediately after drilling and periodically during the life of the well.
3. REGULATION OF SURFACE WATER IN TEXAS20
The industries regulated by the Commission use both surface water andground water for their activities. In Texas, water flowing in Texas creeks,rivers, and bays is owned and managed by the State. Anyone who diverts
such surface water must have authorization – or a water right -- from theState of Texas through the Texas Commission on Environmental Quality(TCEQ) (Texas Water Code, Chapter 11, relating to Water Rights).
Therefore, a person who withdraws surface waters for mining, construction,and oil or gas activities must obtain a water rights permit from TCEQ.
An applicant may apply for a Temporary Water Right permit for short-term
use of surface water. Temporary Water Rights permits authorizing use of
10 acre feet or less and for one year or less may be issued by a TCEQ
Regional Office. In times of drought, the TCEQ may suspend all temporary
water rights permits.
Applicants who seek to use more than 10 acre-feet of water or who seek aterm of more than one year (up to a maximum of three years) must apply
through the TCEQ Water Rights Permitting Team in Austin. TECQ forms,
fees, contacts, and other water rights information may be found on the
TCEQ website (www.tceq.state.tx.us).
4. REGULATION OF GROUND WATER IN TEXAS
A. Regulations of the Railroad Commission of Texas.
Much of the water used in association with oil and gas activities, particularly
the water used in enhanced recovery, is saline or brackish water. With
regards to enhanced recovery more than 90 percent of the water used is
actually highly saline to brackish water produced from the same formations
where the oil fields are located. A very small percentage of the water used
for enhanced recovery is fresh water or slightly saline water produced fromoutside sources as needed to replace the volume of oil removed. Saline orbrackish water is drawn from underground reservoirs that are below thebase of usable quality water. The Railroad Commission requires a permit
for wells associated with oil and gas activities that draw such water fromformations below the base of usable quality water.
The Commission’s Statewide Rule 5 (16 TAC §3.5) requires a Commission
drilling permit to drill an injection water supply well that penetrates the baseof usable quality water. Statewide Rule 13 (16 TAC §3.13) requires that an
injection supply water well that penetrates the base of usable quality water

21
be completed in accordance with the criteria in the rule, and the injection
supply water well must be plugged in accordance with Statewide Rule 14(16 TAC §3.14).
When a fresh water well, whether the well is a rig supply well or an injection
water supply well, is drilled above the base of usable quality water andfresh water is used, regulations other than those of the Commission apply.
B. Regulations of the Texas Department of Licensing and Regulation.
Effective September 1, 2003, the Texas Department of Licensing andRegulation (TDLR) regulates Water Well Drillers under the Texas
Occupations Code, Chapter 1901. Rig supply wells must be drilled by alicensed Water Well Driller; however, Chapter 1901 excludes from thedefinition of “water well” “an injection water source well regulated under§91.101 of the Natural Resources Code.” The Water Well Driller must
submit drilling logs and other required information to the TDLR and theTexas Water Development Board. The completion and plugging of suchwells must comply with TDLR regulations. The GWCDs have the authority
to enforce the plugging regulations for abandoned or deteriorated water
wells within their boundaries.
C. Regulations of Groundwater Conservation Districts.
In Texas, groundwater ownership rights are subject to regulation andcontrol by the courts and the State Legislature. Groundwater may be
managed individually by landowners under the rule of capture, orcollectively by landowners and groundwater conservation districts (GCDs).
Under the “Rule of Capture,” landowners may pump as much water as theychoose, without liability to surrounding landowners who might claim that thepumping is depleting their wells. There are very few restrictions to the ruleof capture.
The Texas Legislature authorized the creation of GCDs as the State's
preferred method of groundwater management (Texas Water Code,
Chapter 36). These districts are empowered and charged to conserve,
preserve, protect, recharge, and prevent waste of groundwater resources
within their boundaries. GCDs may be created through a special legislativeact, a landowner petition process to the Texas Commission on
Environmental Quality (TCEQ), a landowner petition process to join anexisting GCD, or TCEQ initiative in a priority groundwater management

22
area (PGMA). Additional information regarding groundwater management
can be located at the following:
http://www.tgpc.state.tx.us/GWManagement.htm
Chapter 36 specifically does not apply to production or injection wells
drilled for oil, gas, sulphur, uranium, or brine, or for core tests, or for
injection of gas, saltwater, or other fluids, under permits issued by theRailroad Commission. However, it does apply to water wells, including
injection water source wells (“water wells used to supply water for activities
related to the exploration or production of hydrocarbons or minerals”(§36.117(l)).
Under Texas Water Code §36.117, there are certain exemptions,
exceptions, and limitations to Chapter 36. In addition to exemptions forsmall volume livestock and poultry and domestic water wells, there arecertain exceptions for temporary rig supply wells and limitations on injection
water supply wells used in association with oil and gas activity, as well aswater wells associated with surface mining activity.
Section 36.117 includes a permit exception for temporary rig supply wells.
A GCD may not require a permit for the drilling of a temporary rig supply
well (“drilling of a water well used solely to supply water for a rig that is
actively engaged in drilling or exploration operations for an oil or gas wellpermitted by the Railroad Commission of Texas provided that the person
holding the permit is responsible for drilling and operating the water welland the well is located on the same lease or field associatedwith the drilling rig” (§36.117(b)(1)). However, a rig supply water well must
be registered in accordance with GCD rules and must be equipped andmaintained to conform to the GCD’s rules requiring installation of casing,pipe, and fittings to prevent the escape of ground water from a groundwater
reservoir to any reservoir not containing ground water and to prevent thepollution or harmful alteration of the character of the water in any
groundwater reservoir (§36.117(h)). The driller of a rig supply well must filethe drilling log with the GCD (§36.117(i)). In addition, the GCD may require
a water well originally drilled for the purpose of rig supply to be permitted by
the GCD and to comply with all GCD rules if the purpose of the well nolonger is solely to supply water for a rig that is actively engaged in drilling or
exploration operations for an oil or gas well permitted by the Railroad
Commission (§36.117(d)). And finally, the well must be plugged inaccordance with GCD regulations.

23
Section 36.117 also includes a limitation on injection water supply wells.
Although Chapter 36 applies to injection water source wells, Section 36.117
prohibits a GCD from denying an application for a permit to drill andproduce water for hydrocarbon production activities (an injection supply
water well) if the application meets all applicable rules as promulgated by
the GCD (§36.117(g)).
The following tables outline the regulations relating to water wells drilled forwater to be used in oil and gas activities in Texas.
Section 36.117 also includes a permit exemption for water wells drilled inassociation with surface mining. A GCD may not require a permit issued by
the GCD for the drilling of a water well authorized under a permit issued by
the Railroad Commission under Chapter 134, Natural Resources Code, orfor production from such a well to the extent the withdrawals are required
for mining activities regardless of any subsequent use of the water.
However, such a well must be registered in accordance with GCD rules
and must be equipped and maintained so as to conform to the GCD’s rules
requiring installation of casing, pipe, and fittings to prevent the escape ofgroundwater from a groundwater reservoir to any reservoir not containing
groundwater and to prevent the pollution or harmful alteration of thecharacter of the water in any groundwater reservoir, and the driller of sucha well must file with the GCD a copy of the drilling log. Furthermore, a GCD
may require such a well to be permitted by the GCD and to comply with all
GCD rules if the withdrawals from such a well are no longer necessary formining activities or are greater than the amount necessary for mining
activities specified in the permit issued by the Railroad Commission.
REQUIREMENTS FOR WATER WELLS ASSOCIATED WITH OIL AND
GAS ACTIVITIES IN TEXASTCEQ = Texas Commission on Environmental Quality
RRC = Railroad Commission of Texas
GCD = Groundwater Conservation District
TDLR = Texas Department of Licensing and Regulation
Rig Supply Wells that DO Not Penetrate the Base of Usable Quality
Water
AgencyRequirement
Cite

24
TDLR

Rig supply water well must be drilled
by Licensed Water Well Driller.

§1901.151 Texas
Occupations Code

Driller must make and keep a well log §1901.251, Texas
in accordance with TDLR rules andOccupations Codeforms and must send a copy of the log
to TDLR and TCEQ.
Log must include:
1. the depth, thickness, andcharacter of strata penetrated;
2. the location of water-bearing
strata;3. the depth, size, and character ofcasing; and4. any other information required by
TDLR.
Driller must complete the rig supply
water well in accordance with TDLR
standards and procedures.

§1901.253, Texas
Occupations CodeLandowner or operator of abandoned §§1901.254,
or deteriorated water well must plug or 1901.255, andcap the well within 180 days. (NOTE: 1901.256, Texas
A GCD has the authority to enforce
Occupations Codethis section.)
Driller, pump installer, or owner who
plugs a rig supply water well must
submit plugging report to GCD and
TDLR.
GCD

Rig supply water wells are exempt
from GCD permitting requirements
provided:

the rig supply water well is to be
used solely to supply water for a
rig that is actively engaged in§36.117(b)(2),Texas Water Code25

drilling or exploration operations
for an oil or gas well permitted by
the RRC*; andthe person holding the permit is
responsible for drilling andoperating the water well and thewell is located on the same leaseor field associated with thedrilling rig.

Rig supply well must be:§36.117(h), Texas
Water Coderegistered in accordance with
GCD rules andbe equipped and maintained so
as to conform to the GCD’s rules
requiring installation of casing,pipe, and fittings to prevent theescape of groundwater from agroundwater reservoir to any
reservoir not containing
groundwater and to prevent thepollution or harmful alteration of
the character of the water in any
groundwater reservoir.

Driller must submit the drilling log forthe rig supply water well to the GCD.

§36.117(i), Texas
Water CodeThe GCD may require a permit and§36.117(d)(1),compliance with all GCD rules if the
Texas Water Codeexempted rig supply well no longer
supplies water solely to a rig that is
actively engaged in drilling or
exploration operations for an oil or gas
well permitted by the RRC.
Groundwater withdrawn from an
exempt rig supply water well that is
subsequently transported outside theboundaries of the GCD is subject to§§36.117(k),36.122 and36.205, Texas
Water Code26
any applicable production and export
fees.
* The RRC interprets the phrase “a rig that is actively engaged in drilling or
exploration operations for an oil or gas well permitted by the commission”
to mean a drilling rig or a workover rig and interprets “exploration
operations” to include well completion and workover, including hydraulicfracturing operations.
Rig Supply Wells that Penetrate the Base of Usable Quality
Water
AgencyRegulation
Cite
TDLR A driller must notify TDLR and the landowner Chapter 28
or person having a well drilled on
Texas Water
encountering water injurious to vegetation,
Codeland, or other water and determining that thewell must be plugged, repaired, or properly §1901.254
completed in order to avoid injury or
pollution. The driller must ensure that thewell is plugged, repaired, or properly
completed under standards and procedures
adopted by TDLR.
Injection Water Supply Wells that Do Not Penetrate the Base of
Usable Quality Water
AgencyRequirement
Cite
TDLR

Injection water supply well must be
drilled by licensed water well driller.

§1901.151
Texas
Occupations
Code

Driller must make and keep a well log in §1901.251,
accordance with TCEQ rules and forms Texasand must send a copy to the well
Occupations
owner, TDLR and TCEQ.
Code
The well log must include:
1. the depth, thickness, and character27of strata penetrated;
2. the location of water-bearing
strata;3. the depth, size, and character ofcasing; and4. any other information required by
TDLR.
Driller must complete the well under
TDLR standards and procedures.

§1901.253,
Texas
Occupations
Code

Landowner or operator of abandoned or §§1901.254,
deteriorated water well must plug or cap 1901.255, andthe well within 180 days. (NOTE: GCD 1901.256, Texas
has authority to enforce this section.)
Occupations
Code
Driller, pump installer, or owner who
plugs injection water supply well must
submit plugging report to GCD and
TDLR.
GCD

Jurisdiction of GCD applies to water§36.117(l),wells, including water wells used to
Texas Water
supply water for activities related to the Codeexploration or production ofhydrocarbons or minerals. Jurisdiction
does not extend to production or
injection wells drilled for oil and gas, orfor core tests, or for injection of gas,
saltwater, or other fluids, under permits
issued by the RRC.
GCD permit required for injection watersupply wells drilled for hydrocarbon
activities associated with an oil or gas
well drilled after September 1, 1985.

§36.117, Texas
Water Code,enacted effective
09-01-1985.

A GCD cannot deny an application for a §36.117(g),permit to drill and produce water for
Texas Water

28hydrocarbon production activities(injection water supply well) if theapplication meets all applicable GCD
rules.

Code

A GCD permit may regulate:§§36.1131 and36.116

1. Spacing of wells from propertylines or adjoining wells
2. Density
3. Production
4. Completion; and5. Plugging
A GCD permit may also require
submission of certain information andassess production fees.

§§36.120,§36.205 and36.206, Texas
Water Code

Water well must be completed and§§1901.253,
plugged in accordance with TDLR rules. 1901.254, and1901.255, Texas
Occupations
Code
Report of well plugging must be
submitted to the GCD and TDLR.

§1901.255,
Texas
Occupations
Code

Injection Water Supply Wells that Penetrate the Base of Usable
Quality Water
AgencyRegulation
Cite
RRC

A RRC drilling permit is required to§91.101, Texas
drill an injection water source well that Natural
penetrates the base of usable quality Resources Codewater.
16 TAC §3.5
Well must be cased and plugged inaccordance with RRC regulations.

16 TAC §§3.13
and 3.14.

29
Note the paragraph outlined in large font “on the same lease or

field”.
The “same lease” may mean that if afresh or slightly saline water well is used off
the lease is sold or moved, it will become subject to permit by a GCD. The Gulf
Coast Evergreen district has interpreted this to be true and may not recognize the“field” portion of this rule.
The 17-million acre Eagle Ford Field may mean that all water wells drilled in any
county used for hydrofracing or any injection well are not subject to any control bya GCD except registration. It is still unclear if the Eagle Ford play is a single field
or a series of fields.
Another problem exists in the definition of “fresh water”. The TWDB and the
TCEQ view fresh water as equal to or less than 1,000 ppm. It is assumed that thisis the official Texas break point.
Caldwell County contains more than 9,000 wells drilled for oil and gas. Many
producing and abandoned wells have developed casing leaks, which created areasof higher than 1,000 ppm within fresh water zones in the Wilcox sands. These
areas have created some undefined brackish water TRRC and other local and stateagency problems. As long as they are not addressed, it may not be a problem.
As the Gulf Coast Pearsall play develops, it may follow the same conventions as
the Eagle Ford. These two plays are both hydrofrac targets. The Pearsall will
exceed the areas and counties covered by the Eagle Ford. There are somegeochemical differences between the two plays. The Eagle Ford has proved to havethree zones of production being: Natural gas only Natural gas and oil (condensate) Oil
Natural gas is now priced at less $4.00 per MCF, which has pushed the Eagle Ford
play into the liquids geochemical window.

30

Eagle Ford production zones.
The deeper Pearsall play may follow the same pattern dependent upon geochemicalfactors.
Every oil and gas well ever drilled has its own optimum production rate. This
statement is especially applicable to hydrofrac wells. Steep decline curves arecommon to over optimum production levels. That in return leads to re-fracing.
The average hydrofrac Eagle Ford well requires 6.1 million gallons of fresh toslightly brackish water which equates to 18.7 acre feet per well per hydrofrac. It is
forecast that an additional 20,000-30,000 wells will be drilled over the next few
decades focused on shale gas plays in the Texas Gulf Coast.
This may result in spending that will exceed $100 billion dollars. A few operators
are beginning to advocate spending another $4billion on a desalination Gulf of
Mexico pipeline into the shale gas plays.

31
Al of the major shale gas operators are in the initial investigative stages ofrecycling flowback water. The percentage of flowback varies from well-to-welland area-to-area and is largely site specific.

GCD BRACKISH WATER ISSUESAll of the GCD’s will soon face brackish water issues as the population of swells
and essentially doubles over the next few decades.

32

33

Clearly all GCD’s will have to consider desalination of slightly saline and brackish
water as a source for municipal and rural use. This will entail altering portions ofRules, Management Plans and Mitigation Plans.
No GCD should ever cut off their rules at 1,000 ppm or any arbitrary depth. No
potential aquifer should be considered “non-relevant” due to TDS, aquifer
identification or depth. For example, GMA-10 considers the Trinity aquifers tobe “non-relevant” due to TDS levels exceeding 3,000 ppm.
A few large areas of the Carrizo utilized for irrigation would be considered “nonrelevant” under the same criteria.
The TWDB LP-214and Hydrogeologic Atlas No. 3 designates fresh-brackishsaline water in the following table:
Classification
Fresh
Slightly Saline
Moderately Saline
Very Saline

TDS mg/liter
1,000
1,000-3,000
3,000-10,000
10,000-35,000

34

A few West Texas aquifers are set between 5,000-10,000 mg/liter for irrigation andindustrial uses which adds to the classification confusion.
TCEQ lists the Maximum Contaminant Limits for elements and molecules as TDS
levels for reporting and clean-up.

35
Irrigation with TDS levels above approximately 1,000 mg/liter will build up salt
within the soils to the point where they become unusable.
Conflicts will begin to arise over the definition of fresh, slightly saline andbrackish water over TRRC casing rules.
Conflicts will arise over TRRC injection well depths and zones. One notableobjection just surfaced recently in Victoria County.
Litigation will most certainly arise over slightly saline and brackish water uses as
the conflicts arise.
Once again, GCD Rules, Policies, Management Plans and Mitigation Plans will
become increasingly complex and important. These elements are the shields andtransparent instruments to aid in the negation of challenge as well as conservation.

William Feathergail Wilson, PG 21

36

GEOLOGY OF CORRELATIVE RIGHTS
BY
William Feathergail Wilson
Texas PG 21
May, 2012“The correlative rights doctrine is a legal doctrine limiting the rights of landowners to acommon source of groundwater (such as an aquifer) to a reasonable share, typically based on
the amount of land owned by each on the surface above.”

INTRODUCTION
The 82nd Texas State legislators passed three Senate Bills that may create more
problems than solutions, accompanied by a plethora of unintended consequences.
There are many reasons for GCD to promulgate rules including: Compliance with local, state and federal laws
 Proactive management is always more prudent and cheaper than reactive
management
 Carefully crafted rules, Management Plans and Mitigation Plans serve as
partial litigation and disgruntled landowner shields that may at least blunt
anticipated problems stemming from the newly created state laws passed
during the 82nd legislative session and effective as of September 1, 2011
Specifically, these Bills were entitled SB-332, SB-660 and SB-737.
SB-332 was designed use settle the issue of groundwater ownership. The bill
specifies that groundwater is owned by the surface owner, unless severed subject toreasonable rules set forth by groundwater districts. The bill was sponsored andpushed by the Farm Bureau, Texas Southwestern Cattle Association and others.
SB-332 creates some geologic issues that were not anticipated by the collective
wisdom of the Texas State Legislators. Some of these issues will be outlined
below.

37
For example, let us consider a 100- acre tract under the following conditions andgroundwater district rules:
 District designates correlative rights to be 1 acre feet per acre
 Allows the pumping of 100 acre feet per yearo 100 x 325,851 gallons = 32.585 million gallons per year
o 89,274 gallons per day
o 62 gallons per minuteLet’s further assume the landowner plans to install an irrigation pivot system on
the SW corner of the 100 acre site.

38

It can be easily seen that neighbors that own land within 500 feet of the SW cornerof the permitted 100 acres will be losing their ownership of the groundwater
beneath their land by at least 12.1 feet per week per acre owned under SB-332.
This would amount to an estimated 3.9 million gallons per week.
This brings forth some interesting SB-332 questions: What is this “stolen” water worth?
 What is the worth of the damages?
 What would the cumulative drawdown be if the neighbor also owned a 100
acre-foot permit and drilled their well near the neighbor’s SW corner well?
 How could a water district have prevented these problems?
 Could the water district be legally culpable for weak rules?

It is plain this radius of drawdown could impact not just one neighbor, but threeneighbors.

39

It should also be noted that any edge position will impact one or more neighbors.

Potential geologic and district rules might include:Central position
Calculations based upon gallons per minuteCalculations based upon radius of influence
Limitations to the doctrine of 1 acre-foot per acre dependent upon well
position and pump capabilities

It can readily be seen that correlative rights and SB-332 may foster a litany ofproblems for landowners and water districts.
For a second example, let us consider a rural public water system that serves either
an incorporated city and/or rural customers.
The following assumptions are as follows: PWS water well drilled 5-acre fee Pumps 700 gpm, 5 days per week40

Radius of influence 2,000 feet beyond the 5-acre fee.

This calculation indicates that the drawdown will be about 16 feet out to 2,000 feetbeyond the well.

41

Five acres covers an area of about 482 x 482 feet. It is clear that many surrounding
landowners would have a claim on the withdrawn groundwater unless the PWS
either owned or leased the surrounding groundwater property rights under SB-332.
This brings forth the similar questions to the irrigation example outlined in theabove paragraphs.
These are just a few unintended consequences concerning SB-332.

SB-737 lays out the following:“(b) Requires the district, in issuing permits, to manage total
groundwater production on a long-term basis to achieve an applicable
desired future condition and consider:(1) the modeled available groundwater determined by the
executive administrator of the Texas Water Development Board(executive administrator);(2) the executive administrator's estimate of the current andprojected amount of groundwater produced under exemptions
granted by district rules and Section 36.117 (Exemptions;
Exception; Limitations);(3) the amount of groundwater authorized under permits
previously issued by the district;42(4) a reasonable estimate of the amount of groundwater that is
actually produced under permits issued by the district; and(5) yearly precipitation and production patterns.”

The most difficult aspect of SB-737 is the recharge implications sited under item
(5) as shown above. It is also that all permits will be subject to “modeled”
available groundwater. Recall that the TWDB budget has been cut by 30% andapproximately ½ of their modelers were laid off prompting service cutbacks.
This places more of the burden upon the water districts to defend and promulgate
applicable rules to comply with the new laws effective September 1, 2011.
The PCCD must consider these new laws and their unintended consequences as
proactive predictions and applicable rules, groundwater management andmitigations plans.
SB-660 is a complex bill concerning measuring, managing and procedures applied
to the DFC’s. The elements of this bill will have to be incorporated into the Rules,
the Management Plan and perhaps a Mitigation Plan.
The bill forces more spending down to the GCD level including:Monitoring costs
Geological services
Legal services
Modeling costso Sub-regional levelo GMA levelo GCD level43
William Feathergail Wilson, PG 21

44

GEOLOGY OF ASR WELLSBY
William Feathergail Wilson
Texas PG 21
May, 2012

INTRODUCTION

There are many reasons for GCD to promulgate rules including: Compliance with local, state and federal laws
 Proactive management is always more prudent and cheaper than reactive
management
 Carefully crafted rules, Management Plans and Mitigation Plans serve as
partial litigation and disgruntled landowner shields that may at least blunt
anticipated problems stemming from the newly created state laws passed
during the 82nd legislative session and effective as of September 1, 2011
ASR Wells
Aquifer Storage and Recovery wells may pose some very specific problems
stemming from SB-332, SB-660 and SB-737.
An ASR well takes surface water generally from a river or a steam and injects into
an aquifer to be stored and later retrieved. ASR wells are almost always Public
Water Supply Wells. They do require GCD permits to drill and complete as well
TCEQ approval.

45
They are far more expensive than ordinary rural water supply wells and require
extensive planning and surface equipment. Most of the ASR wells exceed$1million dollars.

The schematic shown above outlines a few of the problems and unintended
consequences that may arise from an ASR well. Note that an ASR wells results in“cone or hill of water” above the confining layer subject to the same equations
that describe the “cone of depression” that govern withdrawal of water.

46

SB-332 was designed use settle the issue of groundwater ownership. The bill
specifies that groundwater is owned by the surface owner, unless severed subject toreasonable rules set forth by groundwater districts. The bill was sponsored andpushed by the Farm Bureau, Texas Southwestern Cattle Association and others.
SB-332 creates some geologic issues that were not anticipated.
For example, let us consider a 5- acre tract with an ASR well drilled outside thecity limits or on the edge of the city limits under the following conditions andgroundwater district rules:

47
 The city or the ASR owner may demonstrate they have the surface
water rights
 The ASR owner may not inject beyond the radius of influence without
owning or leasing the groundwater rights of adjacent landowners
 Questions arise as to owns and controls the groundwater once it
crosses ownership boundaries
o Does the groundwater change title when it crosses alandowner’s boundary under SB-332 ?

Radius of influence 2,000 feet beyond the 5-acre ASR fee.

48

This calculation indicates that the drawdown or an ASR “radius of influence” will
be about 16 feet out to 2,000 feet beyond the well.
Five acres covers an area of about 482 x 482 feet. It is clear that many surrounding
landowners would have a claim on the withdrawn and injection of the groundwater
unless the PWS either owned or leased the surrounding groundwater property
rights under SB-332.
These are just a few unintended consequences concerning SB-332.

SB-737 lays out the following:49“(b) Requires the district, in issuing permits, to manage total
groundwater production on a long-term basis to achieve an applicable
desired future condition and consider:(1) the modeled available groundwater determined by the
executive administrator of the Texas Water Development Board(executive administrator);(2) the executive administrator's estimate of the current andprojected amount of groundwater produced under exemptions
granted by district rules and Section 36.117 (Exemptions;
Exception; Limitations);(3) the amount of groundwater authorized under permits
previously issued by the district;(4) a reasonable estimate of the amount of groundwater that is
actually produced under permits issued by the district; and(5) yearly precipitation and production patterns.”

The most difficult aspect of SB-737 is the recharge implications sited under item
(5) as shown above. It is also that all permits will be subject to “modeled”
available groundwater. Recall that the TWDB budget has been cut by 30% andapproximately ½ of their modelers were laid off prompting service cutbacks.
This places more of the burden upon the water districts to defend and promulgate
applicable rules to comply with the new laws effective September 1, 2011.

50
The PCCD must consider these new laws and their unintended consequences as
proactive predictions and applicable rules, groundwater management andmitigations plans.
SB-660 is a complex bill concerning measuring, managing and procedures applied
to the DFC’s. The elements of this bill will have to be incorporated into the Rules,
the Management Plan and perhaps a Mitigation Plan.
The bill forces more spending down to the GCD level including:Monitoring costs
Geological services
Legal services
Modeling costso Sub-regional levelo GMA levelo GCD level

All of these new bills will require considerable time and effort, as well as careful
study.

51

Theis Equation Calculator
http://www.icalcul8.com/theis.php

52

53

54

DIFFERENCE BETWEEN K & T
BY
William Feathergail Wilson
Texas PG 21
May, 2012

INTRODUCTION
There are three fundamental groundwater numbers derived from pump tests.
1. Storage Coefficient (Sc)
2. Hydraulic Conductivity (K)3. Transmissivity (T)The following 2010 North Carolina Division of Natural Resources paper describes
these concepts.

55

Basic Hydrogeology
GROUND WATER, AQUIFERS & CONFINING BEDS
Aquifer - "A water-bearing layer of rock, or of unconsolidated sediments, that will yield water ina usable quantity to a well or spring."
Confining Bed - "A layer of rock, or of unconsolidated sediments, that retards the movement ofwater in and out of an aquifer and possesses a very low hydraulic conductivity."
From these definitions, all rocks can be thought of as either aquifers or confining beds.
Moreover, aquifers are often considered to be unconfined or confined.
An aquifer is considered unconfined if water only partially fills the aquifer materials and water
freely rises and declines along the unsaturated/saturated zone boundary. These unconfined
aquifers are often referred to as water-table aquifers and wells that are opened to these
unconfined aquifers indicates the position of the water-table.
A confined aquifer is generally defined when water completely fills the aquifer materials and isoverlain by a confining bed. A common term for a confined aquifer is an artesian aquifer. The
water level from a well that permits water solely from a confined aquifer to enter the well will
stand at some point above the top of the confined aquifer but not necessarily above the land
surface. The water level in a well open to a specific confined aquifer stands at the level of thepotentiometric surface. If the potentiometric surface is above land, the well is often considered
as a free-flowing artesian well.

Reference: modified from Heath (1993)

POROSITY, SPECIFIC YIELD & SPECIFIC RETENTION

56

Our understanding of porosity provides us the ability to quantify the volume of water containedin our aquifers. Porosity is best understood as the ratio of the voids to the total volume of an
unconsolidated or consolidated material.

Note: n = porosity as a decimal fraction
Vt = the total volume of a material
Vs = the volume of the solids in the material
Vv = the volume of the voids
Often, porosity is expressed as a percentage by multiplying the ratio by 100. Porosity also
depends on the range of grain size (sorting) and shape of the subject material, but not on thesize. Fine-grained materials tend to be better sorted than coarse-grained materials, thereby
exhibiting greater porosities.

By looking at the above table one might conclude that fine-grained materials have the greatest
ability to supply water to a well. This is not the case because physical properties such as
adhesion (the molecular attraction of two different substances) and cohesion (the molecular
attraction of similar substances) limit an aquifer's ability to release water into a well. Water
stored in an aquifer that is retained as a film on the aquifer material or in very small openings iscalled specific retention. Conversely, water stored in an aquifer that will drain under the
influence of gravity is called specific yield. The term effective porosity is often used to describe
specific yield. With concepts of specific yield and retention in mind, let's look at our porosity
chart once again.

As we can conclude, finer-grained materials such as clay have a high porosity but also have ahigh specific retention and low specific yield when compared to their coarse-grained
counterparts, thereby limiting its ability to provide water to a well.

HYDRAULIC HEAD & GRADIENTSAs previously discussed, water entering an unconfined or confined well will stand at a particularlevel. This level is often termed as the hydraulic head and is actually the sum of threecomponents - the pressure head, elevation head and velocity head. The velocity head is often
disregarded because ground water movement in most cases is relatively slow. In practical

57

applications, a depth to ground water measurement is obtained and subtracted from the top of
the well casing elevation to measure total head. Note that the datum plane illustrated below isoften calibrated to sea level.

When ground water level measurements are collected for a specific aquifer and contoured in a
map perspective, a ground water surface map can be generated. Remember, water levelmeasurements obtained from an unconfined aquifer represents the water table surface, andrepresent the potentiometric surface for water levels obtained from a confined aquifer.
The direction of ground water movement can be understood in the fact that ground water
always flows in the direction of decreasing head. The rate of movement on the other hand isdependent on the hydraulic gradient, which is the change in head per unit distance. Thechange in head measurement is ideally in the direction where the maximum difference of headdecrease occurs. In the example below, the hydraulic gradient is determined to be .00641 ft./ft.
(the change in head divided by the change in distance). Notice the units are foot by foot but
can be described in more inconsistent units such as foot per mile.

Reference: modified from Heath (1993)
The direction and hydraulic gradient can be determined if the following data are available forthree wells located in a triangular pattern.
(1) Relative geographic position of the wells.
(2) Distance between wells.

58(3) Total head (ground water level) at each well.
The solution is outlined and illustrated below.
(a) Identify the well that has the intermediate water level.
(b) Calculate where the elevation of the well with the intermediate head would fall along a
straight line between the wells having the highest and lowest heads.
(c) Draw a straight line from the well with the intermediate head to its elevation equivalentplotted along the straight line between the wells having the highest and lowest heads. This line
represents a segment of the water-level contour whereby the total head is the same as theintermediate well(d) Draw a line perpendicular to the water-level contour line just plotted with the well of highest
or lowest head. This line is the line that parallels ground water direction.
(e) Now, calculate the difference between the head of the well and that of the intermediatehead contour by the distance between the well and the contour to reveal the hydraulic gradient.
Thus, ground water flow direction is towards the south east at a hydraulic gradient of .00641
ft/ft.
The direction and hydraulic gradient can be determined if the relative geographic position,
distance between wells and total head are available for three wells located in a triangularpattern.
The solution is outlined and illustrated below (Heath, 1993).
(a) Identify the well that has the intermediate water level.
(b) Calculate where the elevation of the well with the intermediate head would fall along a
straight line between the wells having the highest and lowest heads.
(c) Draw a straight line from the well with the intermediate head to its elevation equivalentplotted along the straight line between the wells having the highest and lowest heads. This line
represents a segment of the water-level contour whereby the total head is the same as theintermediate well(d) Draw a line perpendicular to the water-level contour line just plotted with the well of highest
or lowest head. This line is the line that parallels ground water direction.
(e) Now, calculate the difference between the head of the well and that of the intermediatehead contour by the distance between the well and the contour to reveal the hydraulic gradient.

59

Thus, ground water flow direction is towards the southeast at a hydraulic gradient of 0.001 ft/ft.

DARCY'S LAW & HYDRAULIC CONDUCTIVITY (K)In the mid-1800s the French engineer Henry Darcy successfully quantified several factors
controlling ground water movement. These factors are expressed in an equation that iscommonly known as Darcy's Law.

By rearranging Darcy's Law and solving for hydraulic conductivity (K) in common units we canget a sense of what hydraulic conductivity really represents.

Thus, in practical terms hydraulic conductivity is the volume of water flowing through a 1 ft. x 1
ft. cross-sectional area of an aquifer under a hydraulic gradient of 1 ft./ 1 ft. in a given amountof time (usually a day). If we cancel out our units, we see that hydraulic conductivity is usually
expressed in ft./day.

Hydraulic conductivity ranges approximately 12 orders of magnitude depending upon differing
water transmitting characteristics of aquifer materials. As one may conclude from the chart
below, the volume of water that can flow from our sandy and cavernous carbonate aquifer
materials of the coastal plain are in most cases far greater than our rocks within the Piedmont
and Blue Ridge provinces.

There are also some other terms used when regarding the spatial distribution of hydraulicconductivity within an aquifer. If the value of hydraulic conductivity is the same in all directions,the aquifer is said to be isotropic. If hydraulic conductivity is different in different directions, theaquifer is said to be anisotropic. The terms homogeneous and heterogeneous are used whencomparing hydraulic conductivity at separate locations of the aquifer, regardless whether the60value is the same or different in all directions. The aquifer is homogeneous if hydraulicconductivity is the same and heterogeneous if different. The diagram below shows the four
possible combinations when describing the hydraulic conductivity of aquifers.

Another important factor controlling ground water movement is its velocity. The ground watervelocity equation can be derived from a combination of the velocity equation of hydraulics andour familiar friend, Darcy's Law.

We can solve for ground water velocity by; 1. substituting discharge (Q) by the cross-sectional
area at a right angle to flow direction (A) times velocity (v) and, 2. cancelling our units. When
we do this we discover that velocity (v) is equal to hydraulic conductivity (K) times hydraulicgradient (dh/dl).

In practical terms we know that ground water does not move in open space, rather it moves
through aquifer materials that impedes ground water velocity. To account for this we need toinclude effective porosity (specific yield) to accurately quantify ground water velocity.
Remember, hydrogeologists use effective porosity because this value better represents waterflowing through an aquifer under the forces of gravity. Thus the velocity equation is modified.

Let's take a look at the difference of ground water velocity when comparing characteristics of asandy substrate to that of a clay substrate. As we can see, ground water tends to move quicker

61

in materials with higher hydraulic conductivities (those materials also have higher effective
porosities).

TRANSMISSIVITY (T)Transmissivity (T) is the volume of water flowing through a cross-sectional area of an aquiferthat is 1 ft. x the aquifer thickness (b), under a hydraulic gradient of 1 ft./ 1 ft. in a given amountof time (usually a day). If we think about our definition of hydraulic conductivity, we canconclude that transmissivity (T) is actually equal to hydraulic conductivity(K) times aquifer
thickness (b). Or otherwise denoted as T = Kb. We can also conclude that transmissivity isexpressed as ft2/day because if T = Kb, then T = (ft./day)(ft./1). It is difficult to understand thedifferences between "T" and "K" when first introduced to these terms - the illustration below
should hopefully bring it all together.

62

The differences in transmissivities in our coastal plain vary greatly. Some of our Cretaceous
age aquifers have transmissivites that are low as 100 to 1,000 ft2/day. Conversely,transmissivity in the Eocene age Castle Hayne Limestone can be as high as 50,000 ft2/day!!!

STORAGE COEFFICIENT (S)You'll often hear hydrogeologists speak of the "T" and "S" of aquifers. We now have an
understanding of "T" or transmissivity. The "S" is used to represent the storage coefficient of anaquifer which is the volume of water released from an aquifer per 1 foot surface area per 1 footchange in head. Notice that we are not speaking of water flowing through an aquifer, rather weare referring an aquifer's ability to store water. Mathematically, the storage coefficient isdimensionless as the equation below illustrates.

The size of the storage coefficient is dependent whether the aquifer is unconfined or confined.
In regards to a confined aquifer, water derived from storage is relative to; (1) the expansion ofwater as the aquifer is depressurized (pumped) and, (2) compression of the aquifer. In a
confined aquifer setting, the load on top of an aquifer is supported by the solid rock skeleton

63

and the hydraulic pressure exerted by water (the hydraulic pressure acts as a support
mechanism). Because of these variables, the storage coefficient of most confined aquifers
range from 10-5 to 10-3 (0.00001 to 0.001). Conversely, in an unconfined aquifer setting, thepredominant source of water is from gravity drainage and the expansion of water andcompaction of the rock skeleton is negligible. Thus, the storage coefficient is approximate tovalue of specific yield and ranges from 0.1 to about 0.3.

CONES OF DEPRESSION
As water is withdrawn from a well, the water level in the well begins to decline as water isremoved from storage in the well. The head in the well will fall below the level of thesurrounding aquifer and water begins moving from the aquifer into the well. The water level willcontinue to decline and the flow rate of water into the well will increase until the inflow rate isequal to withdrawal rate. Water from the aquifer must converge on the well from all directions
and the hydraulic gradient must get steeper near the well. For this reason the resultant 3-D
shape of water withdrawal is a called a cone of depression.

The aquifer parameters of transmissivity (T) and storage coefficient (S) are variables that can
dictate the shape of the cone of depression. Relative to a confined aquifer, the expansion ofwater in response to depressurizing (pumping) is very small, yet compression of the rockskeleton is great. This permits the cone of depression to expand and deepen rapidly when
pumped. Thus, lower "S" values create deeper and wider cones than higher "S" value aquifers
that do not deepen and expand as readily. In regards to transmissivity, aquifers of low "T"develop deep and narrow cones of depression and aquifers of high "T" area characterized byshallow and wide cones. The reasons for this are fairly complex and require more backgroundinformation to be explained fully. However, think about the "T" relationship this way - a greater
decline in hydraulic head would be required to move water through a less transmissive aquifer
than a more transmissive aquifer.

64

The application of Transmissivity to drawdown and thereby the radius of influence
becomes a very important issue in permitting and groundwater ownership beneathland parcels.

65
The table below taken from Freeze & Cherry text depicts the ranges oftransmissivity.

66
Utilizing this table of K values based upon lithology, T can be estimated by:
T = K x thickness of saturated aquifer
For example, the Reklaw is a silty sand, while the Carrizo is a clean sand. The
Wilcox falls mainly within the lower end of the silty sand range, but it is far thicker
than the Reklaw.
Another contributing factor is the completion depth of the sands penetrated by eachindividual well.
By applying these concepts, PCCD may be able to better estimate the validity ofpermit requests with respect to geology and groundwater hydrogeology.

67

GROUNDWATER MITIGATION
BY
Robert Wilson, Attorney at Law
William Feathergail Wilson, Geologist, Texas PG 21
March, 2012

A Groundwater Mitigation Plan sets forth specific technical and legal
procedures designed to mitigate Rule challenges.
LEGAL BASIS
Mitigation shall be implemented by the PCCD between landowners andgroundwater right holders via a formal process conducted by ________.
In the case where the PCCD is challenged, mitigation will be conducted by a third
party via a formal process conducted by _______.
(Expand –Change-Rewrite)
TECHNICAL BASIS
The challenging party shall be responsible for the cost of the burden of proof suchas follows: Drilling of at least three observation wells to the same depth as thechallenged aquifer Utilizing adequate software, hardware and third party impartial consultants
to evaluate the validity of the challenge Consult PCCD guidance documents to ascertain the nature of the challenge Follow the PCCD Rules and the laws of the State of Texas concerning
groundwater

68
Special attention should be paid to the PCCD Guidance Document entitled“Geology of Correlative Rights” prior to challenges by both and/or all parties.