# Gr **oundw ate**  **r Flow and T ra**  **nsport ove**  **r Lar ge**  **r V**

**olumes of R**  **ock: Cr**  **oss -**  **Hole Hy**  **dr aulic**  **and T ra**  **cer T**

**es ting** 

**USEP A**  **- USGS**  **Fr actur**  **ed Ro**  **ck W orkshop**  **EP A R**  **egion 2**  **14 January**  **2014** 

# Clair **e Tiedeman and Allen Shapir o,**  **USGS** 

### Iden **tify flow and tr ansport**  **pathwa ys and barrier**  **s between bor**  **eholes.**  

### Use of this inf **o with geologic fr**  **amework helps iden**  **tify locations of connect**  **ed high**  **- K**  **fr actures and**  **lower -**  **K r ock**  **s.**  

### This char **act eriz**  **ation data**  **is import**  **an t t**  **o developing the sit**  **e conceptual**  **model.**  

### Quan **titative analysis of t est**  **data yields estimat**  **es of K va**  **lues.** 

# Purpose of Cr **oss -**  **Hole Hy dr**  **aulic Te**  **st ing**  **(also called aquif er t**  **es ting**  **, pump t es**  **ting)**

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 2**  **Fast Response** 

**No**

**Response** 

## In fr **actur ed**  **ro ck**  **s, hyd**  **ra ulic**  **re sponses**  **can tr ave**  **l long**  **dis tances in short**  **times.**  

## Dr **awdown will not necessarily**  **decr ease**  **with dis tance fr**  **om pumped well.**  

# Expect **at ions:**  **Cr oss**  **- Hole Hy**  **dr aulic**  **Te st**  **s**

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 3**  

### We **ll spacings**  **and open in**  **te rv**  **als**  **Because of high degr**  **ee of het**  **erogeneity ,**  **difficult t o**  **predict distances**  **over which permeable**  **fr actures**  **are connect**  **ed, prior**  **to drilling wells.**   **Bedding -**  **plane -**  **parting fr**  **actures and**  **karst fe**  **atures lik**  **ely well**   ** connect** **ed over**  **longer distances**  **than fr actures**  **in crys ta**  **lline r ocks.**   **Use multiple crit eria**  **when selecting loca tions**  **of new wells –**  **va lue f**  **or char**  **act erizing**  **contamination as well as f**  **or hyd**  **ra ulic t**  **esting.**  **Multilevel wells import ant**  **fo r**  **understanding vertical**  **connections.**  

### Te **sting**  **Monit or**  **wate r**  **levels in as man y wells as possible.**   **Pump & tr ea**  **t sy**  **ste m pr**  **ovides e xc**  **ellen t**  **opportunity fo**  **r using**  **remediation activities t**  **o further**  **char act**  **eriz e**  **hyd rogeology**  **.** 

# Designing Hy **dr aulic T** 

**es ts** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 4**  

### Pr **ocedur e:**   

### Shut down pump in one well of the P&T **sy ste**  **m.**  

### Monit **or water -**  **level rises in obs**  **we lls.**   

### St **art with r elatively short t**  **es ts (run t**  **es t**  **during the da y,**  **with overnigh t r**  **ecovery)**  

### Re **peat f or all wells of s**  **ystem**  

### Adv **antages**  

### No **additional con ta**  **minated water withdr**  **awn**  

### Re **latively short t es**  **ts limit eff ect of**  **shut down on off**  **sit e con**  **ta minan**  **t migr**  **ation** 

# Using Exis **ting Pump & T**  **re at**  **S ys**  **te m f**  **or Cr**  **oss -**  **Hole Hy dr**  **aulic Te**  **st ing** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 5** 

# We **ll Shut down**  **Te st**  **ing in Sedimen**  **ta ry**  **Ro ck**  **s: An Ex ample** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 6**  **1 st**  **Day: Shut down 45BR 2**  **nd Day: Shut down 56BR**  **3 rd**  **Day: Shut down 15BR rain** **24BR open to bed ‘301’**  

# We **ll Shut down**  **Te st**  **ing in Sedimen**  **ta ry**  **Ro ck**  **s: An Ex ample** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 7** 

###  

## In he **te ro**  **ge neous**  **fr actur**  **ed r ock aquif**  **er s,**  **analytical solutions fo**  **r es**  **tima ting**  **K or T fr om**  **hyd ra**  **ulic te**  **st s**  **ha ve**  **limit ed**  **applicability .**   

## Need t **o use numerical model (e.**  **g. MODFL OW**  **) so that he**  **te ro**  **ge neity can**  **be pr operly r**  **epr esen**  **te d.**  

# Analyzing **Cr oss**  **- Hole Hy**  **dr aulic**  **Te st**  **Da ta** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 8**  

### Pr **ocess of dev eloping and calibr**  **at ing**  **gw flow model helps adv**  **ance the 3D hyd**  **ro geologic**  **conceptual model.**  

### Enables consis **te nt s**  **yn thesis of sit**  **e char**  **act eriz**  **at ion**  **da ta**  **– geology**  **, geoph**  **ysics, hyd**  **ra ulics.**   

### Pr **ovides a tool f or under**  **sta nding the**  **3D e ff**  **ects of changes to the flow sy**  **ste m, such as incr**  **eased pumping.**  

### Can be upda **te d as new da**  **ta collect**  **ed**  

### Starting point f **or tr ansport modeling**  

# Va **lue of Modeling f or In**  **te rpr**  **eting Hy**  **dr aulic**  **Te st**  **Da ta** 

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 9**  **Hydraulic Conductivity Representation** 

**Simulated Drawdown** 

## Va **luable fo**  **r iden tifying:**   

### Pa **ths f or r**  **elatively r apid con**  **ta minan**  **t tr ansport**   

### Less permeable volumes of r **ock wher**  **e slow advection and diffusion lik**  **ely dominat e tr**  **ansport**  

## Interpreting **hyd ra**  **ulic te**  **st da**  **ta:**  

### Incorpor **ate heterogeneity! Use geology!**   

### Presence of permeable high **- angle fr**  **actur es migh**  **t be inf err**  **ed from data,**  **but can be difficult t o iden**  **tify their locations**  

## Tr **acer te**  **st ing**  **pr ovides**  **mor e de**  **finitiv e**  **char act**  **eriz at**  **ion of tr**  **ansport pr**  **ocesses** 

# Cr **oss -**  **Hole Hy dr**  **aulic Te**  **st s in**  **Fr actur**  **ed Ro**  **ck s: Final Though**  **ts**

**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 10** **Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 11**  

# Applic **at ion**  **of T ra**  **cer s T** 

**es ts f**  **or Decision Making a**  **t Sit**  **es of Gr**  **oundw ate**  **r Con**  **ta mina**  **tion**
 **Hydr aulic testing monitor**  **s fluid pr**  **essur e r**  **esponses (h yd**  **ra ulic connections)** 
 **G ro**  **undw ate**  **r velocity or pr ocesses**  **aff ecting chemical r**  **esidence times and chemical**  **dilution are**  **difficult to**  **inf er fr**  **om h yd**  **ra ulic**  **inf orma**  **tion alone (especially in fr actur**  **ed r ock)** 

 **If inf orma**  **tion on r esidence time and dilution**  **is needed. . . conduct a test**  **tha t provides a dir**  **ect measur e of these quantities**  ~ ~ K v h n     **Groundwater velocity ,**  **v**  **Estimates of fracture porosity (n) from mechanical considerations are unreliable** 
 **Hydraulic conductivity (K) is usually an order of magnitude estimate**
 **What are the errors in estimating**  **t he hydraulic gradient (**   **h) in highly heterogeneous aquifers ? Cross**  **- Hole Hydr**  **aulic and T ra**  **cer T esting**  **12** 

## Char **act erizing R**  **esidence Time and Dilution**  Designing the injection of r emedia tion amendmen ts**C V** **O C** **C o** **n c** **. (** **m i** **c r** **o g** **r a** **m s** **p e** **r L** **i t** **e r** **)** Continuous pumping

Feasibility of bioaugmentation in strata between 36BR and 15BR. . . What is the travel time and dilution from 36BR to 15BR? Hydraulic communication between monitoring locations is a prerequisite for conducting tracer studies. . .**Cross -**  **Hole Hydr aulic and T**  **ra cer T**  **esting 13**  135 feet

Bromide concentration

- February 2008

(7 months after injection) Tracer injection Pumping 

## Char **act erizing R**  **esidence Time and Dilution**  Designing the injection of r emedia tion amendmen ts

**0.00 0.02**  **0.04 0.06**  **0.08**

**0 10**  **20 30**  **40 50**  **60 c** **o n** **c (** **m g** **/ L** **)**

**time (day s)**  simulated

obs erved Simulations demonstrate slow advection (low K) is responsible for mass retention at greater depths in dipping beds **Naval Air W arfare Center**  **We st T**  **renton, NJ Cross**  **- Hole Hydr**  **aulic and T ra**  **cer T esting**  **14** 

## Pr **ocesses Aff**  **ecting Chemical Migr at**  **ion** Es timating par ameter s governing matrix dif fusion
Characteristics of breakthr ough curves can be used to identify the significance of chemical processes

Simulations for different effective diffusion coefficients 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 BRP-03 15BR Fill Regolith

Fractured Bedrock Inject WithdrawALTITUDE,INFEET

DISTANCE, IN FEET **B B'** 

Storage of tracer solutions at land surface **BRP3**

**10 -2**  **10 -1**  **10 0**  **10 1** 

**1 10**  **100 1000** BromideConcentration(mg/L)

Elapsed Time from Start of Tracer Injection (hours) **0.00 0.20**  **0.40 0.60**  **0.80 1.00** 

**0 200**  **400 600**  **800 1000** FractionofBromideMassRecovered

Elapsed time from start of tracer injection (hours) **BRP3**

**15BR 71BR**  **70BR**

**25BR 90**  **ft Tracer**  **Injection Pumping** 

Bromide Concentration vs. Time at 15BR Bromide Recovery at 15BR **Naval Air W arfare Center**  **We st T**  **renton, NJ Cross**  **- Hole Hydr**  **aulic and T ra**  **cer T esting**  **15** 

# Tr **acer T es**  **t Design**  Tr acer tests can be conducted over various distances (provided h ydraulic perturbations are observed between locations)

 Single

- hole tracer tests can also be designed (point

- dilution, push

- pull, etc.)  Tr acer tests can be designed over hours, days, months or years  Va rious types of tracers are available to quantify processes of interest (inert , reactive , var ying free

- water diffusion coefficients, dissolved gases, bacteria , colloids, microspheres, etc .)  Maintaining the geochemical signature of the ambient groundwater ( ox ic , anoxic, fluid density)  How much tracer mass must be added to register and interpreted a response ? Preliminary estimates of dilution and at tenuation are difficult to derive in fractured rock ( In some cases, tracer tests are not run; they are re

- run! )  Ef fe ct of fluid density in structured media  Designing injection apparatus at land surface, and apparatus in injection and monitoring boreholes
– maintaining geochemical conditions of ambient groundwater; volume of fluid in boreholes may be large relative to fracture volume; borehole volume may dilute tracer responses Tr acer arrival at monitoring wells (> 5 km fr om tracer injection) in the Madison Limestone

# Final Though **ts**

**Controls on F**  **ate, T ra**  **nsport, and**  **Remediation of V OCs**  **16**  **Tracer tests can provide a direct measure of fluid velocity, chemical dilution**  **and attenuation processes**   **Tracer tests provide valuable information to (1) conceptualize**  **processes affecting fate and transport of contaminants,**  **(2) design and implement remediation strategies**   **Tracer tests in fractured rock are likely to be successful under hydraulically**  **stressed conditions, provided the hydraulic perturbation**  **can be monitored in cross**  **- hole**  **tests**  **Single -**  **hole tracer tests are used primarily to estimate in situ**  **process and identify local parameter values. . .less reliable in estimating**  **groundwater velocity**