Title: Letter
Full Citation
Permanent Link: http://ufdc.ufl.edu/WL00001668/00001
 Material Information
Title: Letter
Physical Description: Book
Language: English
Spatial Coverage: North America -- United States of America -- Florida
Abstract: Letter, January 17, 1979, From: L.M. Blain, To: S.C. Bexley
General Note: Box 9, Folder 3 ( SF-SWF 200002/St. Pete/S. Pasco - 1978-1982 ), Item 2
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
 Record Information
Bibliographic ID: WL00001668
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text

P. o. o 3s


(813) 223-38e8

January 17, 1979

Mr. S. C. Bexley
Route 2, Box 2629
Land 0' Lakes, Florida 33539

Dear Bud:

Attached find a Meorandum of January 13, 1978 and another
Memorandum of January 8, 1979 relating to your property. I
am also sending a copy of this letter and the attachments to
Jake Varn for his information.

This is pursuant to your request to keep you advised from time
to time in connection with well field effects on your property.




cc: Jake Varn, Esq. w/attachments

January 9, 1979

TO: K. C. Jones, Hydrologist, Environmental Section
T. F. Rochow, Biologist, Environmental Section
THROUGH: W. D. Courser, Supervisor, Environmental Section
C. H. Miller. Director, Resource Development Division
FROM: B. A. Boatwright, Director, Regulatory Divisionj
RE: ellfield Effects on S. C. Bexley Property, Consumptive Use
Permit Number 27500002
I have reviewed your memorandum of December 13, 1978 which has now become
a part of the file of record on Consumptive Use Permit No. 27500002 for
the City of St. Petersburg's South Pasco Wellfield. Clarification of
Several points is in order for your information and for purposes of future
reference in the file.

After a rather Ulethy review of this matter by Bud Holzschuh and myself
prior to Governing Woard action on the above referenced permit, it be-
cam apparent tMat nomalosly high leakece conditions could exist on
Mr. Bexley's property thus causing calculations of water table decline
based on aquifer coefficients derived from South Pasco Iellfield pump test
data to be biased. That Is, the declines could be ssewn t greater then
those you predicted if thN coeffi ient of leakance on the Bexley property
is greater then 1.3 x 10"- g/ft Because of this possibility the overn-
ing Board ordered the installation of a set of monitor ells, one Floridan
Aquifer and one mwter table to better define the possibility. Although
your calculations are well qualified by the assumption of consistent aquifer
conditions it is important that the concern over the possibility of noma-
lous leakance be recognized not only in this case but in others you may
address in the future.

Further, your memorandum addresses land use changes on the Bexley property
as a source of water table declines. Pasture grasses may evapotranspire
more than natural vegetation thus resulting in water table declines when
natural vegetation is replaced by pasture. The water table declines which
Mr. Bexley is concerned with have occurred in recent years end did not
coincide with the conversion of his acreage from natural vegetation to
improved pasture. Therefore, 17.7 inches of additional water (as indicated
on page three of your mem) is not being lost annually by ET from the
surficial aquifer now as compared to the time the wellfield commenced operations
as a result of land use changes on the Bexley property.

cc: J. B. Butler
B. R. Laseter
H. V. Aiken
Consumptive Use File
J.E. Curren
L.M. Blain

r/. A,/

ba"" I$ 97 r fie o.

TO: S.R. Leetor, Director, Wparbmet of Operatins
MlHM: U.D. C*sreor, S"pervisir, Igfil ow I sectiwm
C.N. Miller, Direlto, Amfemme Devele"uwt 1"ptsl
FWI: LC. Jones. Nydolist, [1qr wntsl Settles c.T

RE: Investigation of Dry Conditions at Mr. S.C. Sexley's Property,
2.5 miles North of South Pasco Weilfield

I ntrodwctiwm
an Fridw Repo It s field iavestilgtion of Mr. S.C. b"Ier's wet
wo tsm.xW to observ A ntrely dry condittes In f Ms
~9V~s*g The pu',71 Is looted appreitmsely 2.3 slles, r o
us $000 pow Weillfi a"d Withle 0sm miles of sow solve"q
watr IfC~l iO.To~~i S~ t~o~~ ~r ts~wmO f e rg fui
wiltcll%)&, WA ob jusivle IM" owIe t 0" IN0
gApethm Fe afield %@0 %d SIVIflemnat effects ofs cypress anes
*id to rigew h etot Mher fectsqs OW contrIbuto to the lor water
table C*qlt% presestly exparlIomteI on his ""Orl.
Alth-ow16 so field Observation wer sumshet c1oM by a 1.5 to^
rainaTI ccorrome Was d4W befwe go Investigotlem, drowlght eomuitieon
Were still puvwt at On tW of go larestiget"Mr. s addttiem to the
field observations, sievrl 04hor 4I were spent omptial esthmtical i
ti* woilfield effects am we os of ieve'stigattwi, COMP11, "I sfell
01W eve ptrinspi rtio" (IT) date, visings previous qiiwestigstless to
the "",s "W Prewing 0 timmem.
Throeinwje factors have beow fsuud Is contribute to the lowe water table
conditions ftht pressatly exist on Or. Bexley's property. They wev
descritood as folleas:
Wellfield Effcts:
Mr. Loixlqrs property lies approaiestely 2.5 miles from the canter of
pupege of the South PAN* Wsllfield and within sin miles of tmon Cypres
Creett Surtartin and EWye-Wilds wallfields. In MoYtion, there are
several priveft lrvl~etlow wall sysse la the ore Afgh one Is mae
pmwiodically. A voels f' the soual So ounaoter *10rwl Is beousi-
the scow of this "all tevestipti.. ebt should to esgulatW of fto
studies orn to be de. The gol. cofese of this stv* was to
the effects Of the SMth Posco Wellfield, the we11f1611 of close
proximity sad greatest bdred effects en the ore. 67 -:

C.R. Laseter Page 2
Re: Dry Conditionf*'S.C. Bexley's Property

To compute the drawdown of the South Pasco Wellfield on Mr. Bexley's
property, several assumptions had to be made: 1) the Floridan Aquifer
has the same transmissivity and storage coefficient between Mr. Bexley's
property and the wellfield; 2) the surficial aquifer has the sam trans-
missivity between Mr. Sexley's property and the wellfield; 3) the confining
bed Is homao.eous and has the same leakage coefficient between Hr.
&exley's property and the wellfleld; 4) wellfield pumpage is an average
of 16 ogd; 5) yearly water table fluctuation is 6 feet annually; 6) the
average ET rate is 37.5 inches per year. The equation used was developed
for the Starkey Wellfield project (ietz; pp. 1061-1074), however, all of
the aquifer properties were changed to define the conditions at the
South Pasco Wellfield as follows:

Transmissivity of Floridan Aquifer 350,000 gpd/ft
Transmissivity of Shallow Aquifer 1,500 gd/ft
Leakance of Confining Bed 1.3 x 10-4 spd/ft3
(Guytoe; pg. 20)
Assuming the above condition are true, the drawdown in the water table
in Mr. Bexley's property due to the pmpee at South Pasco is only 5.9
inches. The drwdon is the potentlietric level is 57.7 inches (see
work sheet). This, however, Is only the effect frwn the closest wellfleld.
Other wells and wellfields In the area would probably double these

The lack of rainfall in the area has had a significant effect on the
lowering of water table levels in the past several years. The average
expected rainfall over the last ten years has been estimated at 50
inches per year at the South Pasco wellfield (Courser; pg. 20) for a
total expected rainfall amount of 250 inches over a 5-year period. The
actual rainfall amount at the wellfield for 5 years since pumping first
began (March 1973-Febrjvry 1978) is 236.94 inches, creating a deficit of
more than 13 inches. gare recently, in the last four months we have
experienced extreme dr(aght conditions. In the period of August 1-
lovenber 30, 1978 only 10.35 inches of rainfall occurred over the wellfield.
The average expected rainfall over the same period for previous years is
estimated to be 17.7 inches, creating a deficit of 7.35 inches in the
last four months alone. This amounts to a drought intensity frequency
of approximately one in twenty years (J. Whalen; personal communication).
Land Use

Land use is also a large factor contributing to the lowering of water
table levels in the area of study. Much of the natural vegetation has
been cleared and replaced with improved pasture. The amount of ET loss
due to converting natural vegetation to improved pasture has been estimated
by the Institute of Food and Agricultural Services (I.F.A.S.) to be 17.6
inches per year greater than the ET values for natural vegetation (Wehle,
1971). The ET values for natural vegetation in the area of study is
approximately 37.5 inches annually. The total ET value for improved
pasture would therefore be 55.1 inches per year, a value 5 inches greater
tian the average annual rainfall.

- Irorandur Decer 13. 1978
"D.R. Laseter Page 3
Re: Dry Conditions S.C. Bexley's Property

Extensive drainage and Irrigation ditching has also occurred, manly
along the southern portions of the property. This will reduce the
waount of runff nto the cypress reas during rainfall events by diverting
runoff water into the ditches. It will lse drain the water tle
aquifer at times Whe the static water level is o v the leel of the
base of the ditch. A vlue for the amount of water lst due to the
extensive ditching-is beyond the scope of this investigation but should
be calculated if future study is warranted.


Uater levels on Mr. kexley's property are affected by many factors.
cells and wellfields surrounding the property lower both the Floriden
and surficial aquifer levels. The South Pasco Wellfield alone contributed
5.9 inches of droadm- in the surfictel aquifer and 57.7 inches of drad-n
in the Floridan Aquifer. Rainfall deficits have contributed to lower
water levels. Since the wellfield as first put into operatit, there
has been a rainfall deficit of at least 20 inches. Finally, land use
practices also influence water levels through lower runoff rates and
higher ET values. For Instance, 17.7 inches of additional water is lest
annually by ET from the surficial aiutfer when pasture grass is substituted
for natural vegetation. rore water is lost when ditching at times
drains wetland areas, reduces runff Into wetland arees, and drains the
water table aquifer.

Mr Lexley's agricultural water management system, created optimu conditions
for agricultural use at the time they were Installed. However, the
recent droughts and wellfields have rade this system overeffective
through tima.


If further study seems necessary at a later date, the following suggestions
might serve as guidelines to follow: 1) determine the total drawdon
effects in the Floridan Aquifer and surficial aquifer from all wells and
wellfields in the 6-mile radius; 2) determine the amount of water loss
due to ditching on Mr. Bexley's property; 3) continue with a monitoring
program as discussed in the previous nmou on the subject, dated May 24,


Attachments: References Cited
Work Sheet

cc: S.A. Boatwright
J.A. Mann

. ---l- --- .--...-

References Cited

Courser, W.D. & P.A. Hernandez. April, 1977. Third Annual Report of the
St. Petersburg-South Pasce Wellfield Study, Environmental Section
Technical Report 11977-1. Southwest Fla. ater M 9nagr;met District,
Drooksville, Florida.
Guyton, William F. aid Assoc. South Pasco Wellfield, regulation and
effects of puping prepared for the Board of County Comissioners,
Pasco County, Florida. TD 407. W5. C2.

iotz, Louis H. "Steady-State Drawdows In Coupled Aquifers." Journal of
the Iydraullcs Ditvslon, SCE. Vol. 104, No. HY7, Proc. Paper
13876, July, 1971. pp. 1061-1074.

Schmidt, Aoeld G., Richard U. Davis. Pertinent Hydrologic Deta and
Design Criteria, Pasco County Wellfield. April, 1971. TD 407. S356.
ehle, Johkn and Harry F. 01Olen. Determination of the Consumptive-
Use of Water by Agricultural Practices, 1971, also described In
SUFR4D Technical miemrand. Available Use Codes, Consumptive Use
Practices, February 21. 1978.

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