AVDA concerns with lysimeter study

4

..

1)1Z 4FT

1.

Problem:

AVDA Concerns and Suggestions for the

Colorado Springs Lysimeter Study

Prepared for Presentation at Meeting Between A'VDA

and City of Colorado Springs, February 27, 1995.

It is apparent from the 1993 and 1994 data collection seasons that there is significant variability

in measured application rate between individual application gages at the same lysimeter sites.

It is also apparent that there is greater scatter in the distribution of effective application /

potential consumptive vs. deep percolation / effective application at small lysimeter sites at

which only two application gages are installed in comparison to the large lysimeter sites.

Suggestion:

Install one additional application gage at the small lysimeter sites and two additional application

gages at the large lysimeter sites to eliminate some of

the variability associated with non-uniform

sprinkler applications. We

believe that the additional gages will provide a better estimate of

actual application at the study sites. The

attached figure shows what we

believe to be the current

configuration of lysimeters and application gages and the proposed additional application gages

at the small and large lysimeter sites.

2.

Problem:

We

have noticed a recurring problem of full application gages at several of the study sites. A

full application gage gives no reliable measurement of the actual application at that site during

that period. We

have also noticed that there has been no consistent volume attributed to a full

application gage in the data reporting.

Suggestion:

Determine which sites or under what circumstances application gages become full and revise data

collection practices to obtain application gage measurements before they become full.

3.

Problem:

During our field visits we noticed several sites with sloping lawns and downspout splashblocks

upgradient of the lysimeters. It is our belief that these lysimeters are collecting water that can

contribute to measured lysimeter return without being measured or accounted for in the

application gages.

Suggestion:

Regrade or construct a low berm upgradient of the lysimeter and application gauges to prevent

surface flow from entering the lysimeters.

FEB-24-1995 14:11 TED ZORICH & ASSOC. P.01 —bk4rr

4.

Problem:

The lawn at lysimeter site 76 at 5640 Wilkerson Pass Drive is not being watered with an

installed sprinkler system and the installed irrigation water meter is not being used to measure

water applied to the lawn.

Suggestion:

Attempt to renegotiate with the property owners at site 76 to use the installed sprinkler system

and irrigation water meter. This issue is especially important at this site because of the presence

of the large lysimeter at this location.

5.

Problem:

During our site visit it was noted that there is an on-going problem with standpipe caps being

stolen or damaged. An open standpipe is an obvious direct path through which additional water

could enter the lysimeter.

Suggestion:

Secure standpipe caps to protect them from vandalism and damage from lawn maintenance

equipment. Standpipe caps could be better protected by lowering them further below the lawn

grade, providing threaded caps that would require a wrench for removal, or enclosing the caps

in a subgrade box similar in nature to a large sprinkler head or valve box.

6.

Problem:

During 1994 the City experienced a problem with two of the large lysimeter sites wherein the

soil volume within thc lyiiiits btAkillIG utluiatetl yet nu return flow could be

removed through

the collection standpipes. It is generally believed that the intake screens of the original

standpipes at the bottom of the lysimeters has become clogged. During the irrigation season,

drive point samplers were installed at these locations and used to remove the water from the

lysimeters. Much care was given to the design and installation of the large lysimeters to prevent

applied water from bypassing the root zone and contributing directly to measure(' return flow.

It is reasonable to question whether the drive point samplers produce a path of direct bypass of

applied water to the bottom of the lysimeter.

Suggestion:

Remove the drive point samplers and develop an alternative solution to the standpipe clogging

problem that is mutually acceptable to the City and the AVDA. The City and the AVDA have

proposed similar alternative designs to install a new standpipe with a perforated horizontal drain.

, FEB-24-1995 14:12 TED ZORICH & ASSOC. P.02 Li / C.. trr"/ .

-.---7.

Additional Concerns:

*

_{Different amounts of irrigated acreage have been reported at lysimeter sites 36,}

_44,

_76,

and 113. This ambiguity calls into question the accuracy of the reported irrigated area

at the other 14 small lysimeter sites for which only one value has been reported,

*

_{The period of measurement has not been noted on the reported total monthly water use.}

Do these water use readings reflect a single month's use or combinations of months

based on meter reading dates?

*

_{The measured precipitation data show considerable variability. In addition, the average}

precipitation at city-wide sites does not correspond closely with the average precipitation

at the six large lysimeter site.

* _{Wayne has a concern about the transmissibility of water between the} soil and the gravel pack.

FEB-24-1995 14:12 TED ZOR I CH & ASSOC.

Jou .\r/C,VS•

P.03

••

TED ZORICH & ASSOCIATES, INC.

7333 West Jefferson Ave. Suite 210 Lakewood, Colorado 80235 (303) 980-0030

k4imilt)14064.--AfriAislor4

4t

...

_

I

CHECKED BY . DATC , " SCALE • • • • • • •••• •••••• • „ . ... • . •..

AFFLICatt4.

(OM

kr

4t1K.

. -to

A&fri-u4

'

110N1

AWAV6

- Lcc4-i10744

x

_{(mare. -Fitasfr)}

Pet.-17

VT4

I

r.

our • 06-1- L.-4*(as4;17,t2.__

417

4alttitpric,4j1

_Lt.-our

.r5Aci--Lt*

,64No Two AFFUGAIltN.

CiAtte;

P.ZP.N.1 •.*tat, 1,-'.

(itenfAr--tz- •

• ••

...'...

_ .1111011MMINIY

••

MAR-06-1995 15:34 TED ZORICH & ASSOC. P.c12

March 6, 1995

Mr.

Philip C.

Saletta

Mr.

Kevin D.

Lusk

Colorado Springs Utilities

Water Resources Department

P.O. Box 1103, Mail Code #630

Colorado Springs, CO 80947

Re:

Colorado Springs Lysimeter Study

Dear Phil and Kevin:

DRAFT

We

appreciated the opportunity to meet with you to

discuss the AVDA's ongoing interest and

involvement in the City's lysimeter study. This

letter restates the concerns of the AVDA and

summarizes our understanding of the discussions

during our meeting on February 27,1995.

1.

Problem:

It is apparent from the 1993 and 1994 data collection

seasons that there is significant variability

in measured application rate between individual

application gages at the same lysimeter sites.

It is also apparent that there is greater scatter

in the distribution of effective application /

potential consumptive vs. deep percolation / effective

application at small lysimeter sites at

which only two application gages are installed

in comparison to the large lysimeter sites.

Resolution:

The City agreed that this is a problem

and will install additional application gages at both

the

small and large lysimeter sites. At the small

lysimeter sites one of the existing two application

gages will be moved and a third application

gage installed to form an equilateral triangle (as

closely as practicable) around the lysimeter.

At the large lysimeter sites two additional

application gages will be installed around the

small lysimeter away from the large lysimeter to

form an equilateral triangle (again, as closely

as practicable) around the small lysimeter.

At

both the small and large lysimeter sites site

specific conditions will be considered such that the

additional application gages are not placed

in locations that might yield nonrepresentative

application measurements.

MR-OS-1995 15:34 TED ZORICH S. ASSOC.

DRAFT

Mr.

Philip C.

Saletia.

Mr. Kevin D.

Lusk

March 6, 1995

Page 2

2.

Problem:

We

have noticed a recurring problem of full application gages

at several of the study sites. A

full application gage gives no reliable measurement

of the actual application at that site during

that period. We

have also noticed that there has been no consistent volume attributed

to a full

application gage in the data reporting.

Resolution:

The City recognized the problem and stated that they

had found no systematic cause for the full

application gages. That is, not all application gages at

a site were

full at the same time,

application gages did not consistently fill after large

precipitation events, and a particular

application gage was not always full suggesting a nonuniform

sprinkler head spray problem.

The City agreed to provide documentation explaining their data

adjustment procedure using

time-series trends and correlations with neighboring application gages.

3.

Problem:

During our field visits we noticed several sites with sloping

lawns and downspout splashblocks

upgradient of the lysimeters. It is our belief that these lysimeters

are collecting water that can

contribute to measured lysimeter return without being measured

or accounted for in the

application gages.

Resolution:

The City expressed their belief that the length of time

during which a particular lysimeter or

application gage would be exposed to sheet flow and the negligible

hydraulic head of such flow

would have little or no effect. on long term results.

The AVDA continued to express their

concern that the relationship between water application

and deep percolation at these sites may

be being altered because of surface run-off to the lysimeter

or application gages. The AVDA

reiterates its suggestion that a low berm be constructed

or regrading be performed to prevent

surface run-off from entering the lysimeters or the application

gages.

4.

Problem:

The lawn at lysimeter site 76 at 5640 Wilkerson Pass

Drive is not being watered with an

installed sprinkler system and the installed irrigation water

meter is not being used to measure

water applied to the lawn.

MAR-OS-1995 15:35 TED ZORICH & ASSOC. P.

DRAFT

Mr.

Philip C.

Saletta

Mr.

Kevin D.

Lusk

March 6, 1995

Page 3

Resolution:

The City will discuss the issue with the property

owner and request that the sprinkler system be

used. If this is not acceptable, a hose bib will be placed

after the installeii irrigation water meter

and the owner will be requested to use this

installation for all lawn watering. The AVDA

requests that the City inform us about how this issue

is resolved.

5.

Problem:

During our site visit it was noted that there is an

on-going problem with standpipe caps being

stolen or damaged. An open standpipe is an obvious

direct path through which additional water

could enter the lysimeter.

Resolution:

The City will review maintenance records to determine

which sites require some modification

to the standpipe caps. Several alternatives solutions

were discussed including lowering the cap

height further below the ground surface and installing

a protective enclosure such as a meter box

or an irrigation valve box over the standpipe cap.

The City agreed to inform the AVDA

of their

selected solution and at which sites it is performed.

6.

Problem:

During 1994 the City experienced a problem

with two of the large lysimeter sites wherein the

soil volume within the lysimeters became saturated

yet no return flow could be removed through

the collection standpipes. It is generally believed

that the intake screens of the original

standpipes at the bottom of the lysimeters has

become clogged. During the irrigation season,

drive point samplers were installed at these

locations and used to remove the water from the

lysimeters. Much care was given to the design

and installation of

the large lysimeters to prevent

applied water from bypassing the root zone

and contributing directly to measured return flow.

It is reasonable to question whether the drive

point samplers produce a path of direct bypass of

applied water to the bottom of the lysimeter.

Resolution:

The City agreed that the drive point samplers

were a problem and will remove them prior to the

1995 irrigation season. The holes will be

backfilled and compacted to ambient conditions to

the

extent possible. Several alternative designs

for a new standpipe and horizontal drain to be

installed through the sidewall of the large

lysimeters were discussed. The City and the AVDA

mutually agreed that a short (approximately 1

ft. in length) section of steel pipe perforated

around its circumference, end-cut at an angle,

and slotted or serrated at the angle cut, will be

driven into the existing gravel pack through

a hole cut in the lysimeter sidewall. An exterior

MR-05-1935 15:35 TED ORICH & ciSSOC. P.05

DRAFT

Mr.

Philip C.

Saletta

Mr.

Kevin D.

Lusk

March 6, 1995

Page 4

flange will be welded to the lysimeter and checked

for water tightness. The horizontal drain will

be connected to the surface with a vertical

riser similar to the riser for the existing standpipe.

Additionally, the City will attempt to unclog or remove

the existing screen from the original

standpipe while the lysimeter is partially excavated

for the installation of the new standpipe.

7.

Additional Concerns:

•

Different amounts of irrigated acreage have been reported

at lysimeter sites 36, 44,

76,

and 113. This ambiguity calls into question the accuracy

of the reported irrigated area

at the other 14 small lysimeter sites for which only

one value has been reported.

Resolution:

The City will verify the irrigated areas at the 14

small lysimeter sites and report the

results to the AVDA.

•

The period of measurement has not been noted on the

reported total monthly water use.

Do these water use readings reflect a single month's

use or combinations of months

based on meter reading dates?

Resolution:

The City's lysimeter technicians will read the whole

house meters where possible and

will read and report meter readings for both the

irrigation meters and the whole house

meters more frequently.

•

The measured precipitation data show considerable variability.

In addition, the average

precipitation at city-wide sites does not correspond closely

with the average precipitation

at the six large lysimeter sites,

Resolution:

The City has been using precipitation data from the

NOAA station at the Colorado

Springs Airport for both its potential consumptive use

calculations and in its accounting

procedures. The City and the AVDA will discuss

the issue at a later date with regard

to recharge and the groundwater modelling effort.

•

The transmissibility of water between the gravel pack

at the bottom of

each lysimeter and

the overlying soil profile.

MR—O5-1995 15:35 TED ZORICH 3. R3500.

DRAFT

Mr.

Philip C.

. aletta

S

Mr.

Kevin D.

Lusk

March 6, 1995

Page 5

Resolution:

Soil water movement in the lysimeter in contrast with surrounding

ambient conditions

was discussed. It was recognized that the presence of a gravel "lens"

in the bottom of

the lysimeter presented a deviation from ambient conditions and

that the standpipe

introduces an artificial atmospheric pressure in the soil water (positive

with respect to the

usual negative soil water pressure or soil water suction). It was generally

agreed that this

represented a limitation in this lysimeter design and that refinement was

probably better

left to a research program such as the current CSU study.

Finally, the AVDA would like to request that they be notified

when modifications to the

lysimeters are being performed or if lysimeters are being removed,

relocated, or excavated for

maintenance. Please let us know if your understanding of what was

agreed to is different from

ours.

Sincerely,

Bruce E. Kroeker, P.E.

Brett W.

Gracely

BEK/BWG

cc:

Board of Directors, AVDA

Carl Genova

Catherine Kraeger-Rovey

Mike Mitchell

Wayne Whittaker

JOHN UNDEM CARLSON MARY MEAD HAMMOND WILLIAM A. PADDOCK

MONTGOMERY WRAY WITTEN MELANIE KOPPERUD BACKES LEE H. JOHNSON

PETER C. FLEMING

CARLSON,

HAMMOND &

PADDOCK

ATTORNEYS AT LAW

1700 LINCOLN STREET, SUITE 3900 DENVER, COLORADO 80203

April 30, 1992

Michael T. Mitche sq.

Mitchell 1, P.C.

1103 iles Peak Drive, Suite 201

rker, Colorado 80134

Re: Colorado Springs Lysimeter Study

Dear Mike:

TELEPHONE (303) 861-9000 TELECOPIER (303) 861-9026

The meeting of Colorado Springs and the AVDA on April 29, 1992, was productive. I am going to try to set out what I understand to have been resolved including a few points Wayne Whittaker, Carl Genova, and Philip Saletta discussed by telephone.

First, however, I want to say that I recognize generally that in many instances the AVDA has made recommendations it believes would lead to a better study and that, for a variety of reasons, not all of those recommendations have been incorporated in the work plan that was decided upon at the meeting. It is not my intention to imply that the AVDA has relinquished its position that the study would be better if each of its recommendations were incorporated. Rather, as I understood the gist of our discussion, I believe the intent is to move forward with the study according to the work plan and each party may then make of the results of the study what they will.

On the same note, the City has not relinquished its position that the work plan far exceeds the requirements of the Stipulation of July 5, 1991, but it is also willing to proceed with that work plan.

With regard to the specific issues decided:

1. Irrigated Area:

At the six sites at which deeper lysimeters are installed, the City will measure the area irrigated, will meter the amount of water applied to that area for irrigation, and will also report the

total amount of water used at the site. In order to facilitate this, we agreed that only sites with sprinkler systems would be chosen for the deep lysimeter sites. We also discussed several

specific cases. In all cases where possible, the City will measure

CARLSON, HAMMOND & PADDOCK

Michael T. Mitchett, Esq. April 30, 1992

Page 2

land for irrigation. We did, however, acknowledge that there may be some exceptions. Basically, these will be explored by the City, reported to Ted Zorich & Associates ("TZA"), and then resolved on a case-by-case basis. The irrigation water meters will be read once a week.

2. Site Locations:

A. AVDA wished to have the six deep lysimeter sites located so that each is in a different part of the City and each is on a different soil type. We agreed that the sites would be sites 44, 72, 78, 113, 905 and 909. The selection of these sites is still subject to the City being able to obtain the necessary legal and physical access to the sites and finding suitable field conditions. AVDA is aware of the time line for obtaining access, building the lysimeters and installing them.

B. With regard to the remaining 14 sites of the 20 "Stipulated Study" sites, the following sites were chosen, subject to obtaining necessary legal and physical access:

3 52 5 66 8 71 10 79 19 87 32 94 36 106

Together the six deep lysimeters, the six small lysimeters at the deep lysimeter sites, and these fourteen small lysimeter sites comprise the sites for collecting data specified in the July 5, 1991, Stipulation and are referred to as the Stipulated Study sites.

At this time, the City would like to recommend substituting site number 6 for site number 3 due to recent vandalism of the application gage at Sabin Junior High School, site 3. Site 6 was a site originally proposed by the City which TZA approved.

Colorado Springs intends to monitor another 14 sites from the original study in more or less the same manner as they were monitored in the original study. AVDA stated that it took no position on any aspect of that City activity, except that the data collected from those sites must be recorded separately. The City will record the data separately and will provide the data from these sites to AVDA.

CARLSON, HAMMOND Ex PADDOCK Michael T. Mitchell, Esq.

April 30, 1992 Page 3

3. Data Collection:

The City will monitor the Stipulated Study sites on Monday, Wednesday and Friday of each week during the irrigation season, including precipitation gages at the six deep lysimeter sites. Though the City's priority for its lysimeter staff is data collection, this monitoring is subject to emergency conditions that may interfere with data collection. The City also collects precipitation from four automated City weather stations and will provide daily precipitation data from those stations to AVDA as well. The City obtains precipitation data from the federal weather station at the Colorado Springs airport and will provide that data to AVDA, as it is available to the City.

4. Data Transmittal:

The City will send copies of field data sheets to TZA every two weeks. The City will enter the data in a computer data base and will send a copy of that data base to TZA in July, September and October. The City will endeavor to have the computer data base as up to date as possible when transmitting it but can not commit to that, due to the priority of field data collection over computer data management.

5. Application Gages:

At the six deep lysimeter sites, the City will install two additional application gages in addition to the existing gage at the existing small lysimeter, for a total of three application gages. The City will attempt to place the two additional application gages so that, with the existing gage, they form an equilateral triangle around and close to the new deep lysimeter.

At the other fourteen Stipulated Study sites the City will add one additional application gage on the other side of the existing small lysimeter, 180° from the original application gage.

6. Catch-Can Study:

The AVDA has decided not to take a position on the use of a catch-can study. The City will discuss this, as well as the other issues, with the State. The City does believe a catch-can study is necessary.

4, 4 po

CARLSON, HAMMOND & PADDOCK

Michael T. Mitchell, Esq. April 30, 1992

Page 4

7. Deep Lysimeter Design and Installation:

The City will construct the six deep lysimeters so they are one meter by one meter by five feet deep. Angle iron will be welded to the inside walls for structural support as needed. Care will be exercised to back fill carefully beneath the angle iron. Angle iron may also be welded to the inside walls of the lysimeter at the top of the gravel filter.

The City will install the six deep lysimeters so that the top of the lysimeters is at least three inches below the surface of the ground. During the installation, the sod will be cut at least several inches beyond the lysimeter edges, removed, then replaced after the lysimeter is backfilled. Before backfilling, the lysimeter walls from the top of the lysimeter to the top of the gravel filter will be coated with petroleum jelly to a thickness of at least 1/4 inch.

8. Other Aspects of the Study:

The City will continue the study in the same fashion as the original study unless modification is indicated in Philip Saletta's April 9, 1992, letter or this letter with this letter taking precedence.

I think this letter sets forth the work plan for the Stipulated Study. If you think otherwise, please let us know as soon as possible so that we may resolve any differences and move forward. cc: Philip Saletta John Kaufman Carl Genova Wayne Whittaker Peter Fahmy Dave Nettles MWW:jdf MWW-1482 Yours truly, a/ M. Wray Witten

C P ci

(1-9

WATER DEPARTMENT•

Resources & Planning

CITY OF COLORADO SPRINGS

April 9, 1992

Mr. Bruce Kroeker, P.E. Ted Zorich & Associates Suite 210

7333 W. Jefferson Avenue Lakewood, CO 80235

Mr. Dave Nettles

Division of Water Resources 800 8th Avenue

Greeley, CO 80631

Dear Bruce and Dave:

I have received both of your letters and I have reviewed and considered your suggestions regarding the ongoing lysimeter study to be performed in accordance with the stipulation between the City, the State and the AVDA. I have been informed by my attorney, Mr. Wray Witten, about a discussion he had with Mr. Michael Mitchell, attorney for the AVDA, in which Mr. Mitchell stated that the monitoring frequency I originally proposed would be acceptable. _{Mr. Mitchell also stated that the 14 additional} lysimeter sites could be monitored at a different frequency if

the data was recorded separately. With this additional

information, I would like to respond to your letters with the following proposal:

1) _{Metering. This may just be a point of clarification, and I}

agree that the stipulation specifies that the irrigated area and the water use for irrigation is to be measured. We have always intended to comply with the stipulation and will install the meters to measure water use for irrigation at the 6 large lysimeter sites. If for some unforeseen reason there is a problem in doing •that at any of these sites I will contact you as soon as I am aware.

2) _{Large Lysimeter Design. The large square lysimeter at}

CWRRI is a total of 4 feet in depth and the angle iron welded on the inside of the CWRRI standard lysimeter is only three inches from the top based upon information provided to me by Dr. Ramchand Oad. The City agrees to construct large square lysimeters similar in size and shape to the large

square lysimeter in the CWRRI study. The City will

similarly weld angle iron inside the large square

lysimeters. _{I believe this addresses Wayne Whittaker's}

30 S. Nevada Ave., Suite 603 • TEL 719-636-5681 FAX 719-473-0779

Mr. Bruce Kroeker, P.E. Mr. Dave Nettles April 9, 1992 Page Two 4 5 6 7

concern about lysimeter design. Also, the City's large lysimeters will have a standpipe assembly attached to the bottom of the lysimeter. I understand your concern to have square lysimeters so there is consistency with the CWRRI study. As in the past we will routinely inspect and maintain the lysimeter to prevent leakage down the inside edge.

Data Submittal Schedule. The City will send copies of the field data sheets to the State and AVDA every two weeks. Since you will have this data and will be evaluating it on a frequent basis, we will send you computer data summaries on a diskette twice per year at the middle and at the end of each irrigation season, if you request.

Lysimeter Backfilling and Compaction. We are certainly willing to excavate and recompact either of the lysimeters you suggested. I believe that this will depend on how the lysimeter installation goes In the field. If it is possible to remove the upper one foot of soil with a backhoe and successfully replace it with out much disturbance,

believe that recompaction of the adjacent small lysimeter may not be necessary. We are certainly are willing to work with you regarding this issue and other issues regarding field installations.

Catch-Can Study. The City is willing to perform a catch-can study at each of the large lysimeter sites. This would be performed just one time to help site the large lysimeter and application gage at each location. I believe that the existing application gauges are close enough to the lysimeters to receive the same application as the lysimeter.

Application Gages. The City will install three application gages at the 6 combined large and small lysimeter sites. The City will also install two application gages at all the remaining 28 small lysimeter sites.

Lysimeter Site Selection. The City agrees to the 34

lysimeter sites proposed for continuing monitoring in the TZA1 letter dated April 1, 1992 with one exception. Lysimeter site 12 was removed and given to the CWRRI for their study. I would recommend that site 18 be substituted for site 12. Regarding the recent TZA letter dated April 3, 1992, the City agrees to try to install a large lysimeter at site 81 rather than site 43. I have some reservation about site 81 since the lawn at this site is moderately

steep, irregular in shape and is a relatively small area to install a larger lysimeter and we are subject to these

Mr. Bruce Kroeker, P.E. Mr. Dave Nettles

April 9, 1992 Page Three

8

field circumstances. At this time, I believe the other 5 sites we selected should not pose any serious field installation problems. Any of the small or large lysimeter sites we agree upon, however, are still subject to landowner approval. Attached is a list of sites we are now proposing.

Data Collection. It is not necessary to monitor the lysimeter sites on a daily basis. Technically, the lysimeter study is intended to determine the return flow based upon total application, not application pattern. We have agreed to monitor rainfall at the 6 large lysimeter sites and we have agreed to monitor 20 sites three times per week on Monday, Wednesday and Friday. The City will also monitor 14 additional sites one to two times per week. When we first agreed to conduct this ongoing lysimeter study, daily monitoring was not contemplated and it would cause an unexpected and significant increase in manpower and cost to the. City. I understand that the AVDA has agreed to these monitoring schedules provided that the data from the less frequently monitored sites is recorded separately on a another field data sheet.

I look forward to our agreement on these issues so we can immediately begin fabrication and installation of the large lysimeters. When we reach agreement on these issues I will also develop a form that is more suitable to submitting field data to you. Please call if you wish to discuss this further or wish to meet in person. In any case, let me know as soon as possible if you accept these provisions so we can begin fabrication of the large lysimeters, begin. installation of the additional application gages, and make adjustments to our monitoring schedule.

Respectfully submitted,

Philip C. Saletta, P.E. Senior Resource Engineer

Resources & Planning Division

jkw c: John Kaufman Michael Mitchell Phillip Tollefson ,Wayne Whittaker . M. Wray Witten

LYSIMETERS PROPOSED FOR CONTINUED MONITORING

LARGE LYSIMETERS

Proposed Sites Alternate sites

6 (9-(,- go 3 44- 87 60N, 4 78/ 43 81 17 905

'71

Sites proposed . Sites proposed for

for M-W-F 1-2 times per week

monitoring monitoring 3 8 5 18 10 27 32 39 36 42 52 56 66 76 71 86 72 101 79 109 87 152 94 154 106 162 113 909

f .A. I, IN CANAL. CZ) M E:' A. 1\T 'Y.

917 Elm Ave., P.O. Box 352, Rocky Ford, CO 81067 Ph. (719) 254-3389

April 15, 1992

Mr. Philip C. Saiey,ta, P.E.

Senior Resource gineer

Resources & Plnning Division Water Department

P.O. Box 110i, Mail Code 630 Colorado Spi.ings, CO 80947-0779

Dear Philip:

Receipt is acknowledged of the copy of your letter of April 9, 1992 addressed to both Mr. Bruce Kroeker, P.E. and Mr. Dave

Nettles. A copy of your letter was not sent to Carl Genova, who

with me was appointed by AVDA to represent the Association's

interest in negotiations with Colorado Springs for the continuing lysimeter study. I have taken the liberty of forwarding a copy for his perusal.

Carl and I have remained ready, willing and able to meet with representatives of Colorado Springs in an attempt to reach agreement on the areas of concern for a continuing lysimeter

study and have not authorized others to meet separately, or enter into agreements on our behalf. As was pointed out in our meeting of February 11, 1992 the following areas of concern will need to be resolved between AVDA and the City of Colorado Springs.

1. One large lysimeter installed in each of the six areas of the service area which was subdivided on the map during the meeting in TZA's office, February 11, 1992. A large lysimeter location still has not been assigned to the northeast area.

2. Design of the large lysimeter to address the concern of AVDA that lateral movement of water is stopped by the side of the lysimeter and thus does not represent the natural flow of applied water outside of a lysimeter. The large lysimeter with baffle installed three inches from the top does not address the concern of AVDA, however, suggestions may be proposed for changes which would address such concern.

3. Design, number, location and installation of lysimeters to provide a representative sample of data.

Mr. Philip Saletta April 15, 1992 Page 2

4. Data collection and submittal. Precipitation was measured daily in the original study. AVDA had expected that such measurement might continue on a daily basis during the

irrigation period at the six large lysimeter sites and had hoped that application gauges could be monitored at the same time. It was not expected that pumping of the lysimeter catchment basin would be required at such frequency. AVDA would expect that a copy of field notes would be mailed at the time such notes are received by Colorado Springs, without benefit of engineering review and adjustment.

5. Metering of water applied to the irrigated area.

6. Number, design and location of precipitation and appli-cation gauges.

We would like to meet with you soon and would appreciate the setting of a time and place which will fit both your schedule and that of TZA.

Sincerely,

1,61WZ

Wayne W. Whittaker, Secretary

cc. Bruce Kroeker, P.E. David L. Nettles, P.E. Michael T. Mitchell, LLB Carl Genova