HomeMy WebLinkAbout1975-03-11 Report on Variancef�
Marc►! 11, 191
:lonaldi K. Rippel
Land-- '
cape Architect/Planner
U190 Woodside Road
Shorewood, Minnesota 55331
Mr. Frank Voigt
Dorsey Marquart Windhorst West & Halladay
2400 First National Bank Building
Minneapolis, Minnesota 55402
Mr. Voigt,
Responding to your request that I prepare an analysis of
a proposed variance by Podany, owner of lot 7, block 1,
Carman's Cove, Orno, with respect to the Halladay residence
located on lot 6, block 1, Carman's Cove, Orno MN, I am
submitting the following report.
A brief of my professional education and experience is
submitted as an attachment along with exhibits A.B.C. and
D relating to my analysis.
The following observations and comments are based upon a
personal site inspection and discussion with Mr. and Mrs.
Halladay at their home; agumented with site photographs
and the plot plan prepared by Cardarelle b Assoc., dated
January 24, 1975 as submitted with the Podany application
for a variance. As of Thursday, March 6, 1975, the City
of Orno had not received a drainage and grading plan, a
recommendation from the Minnehaha Creek Watershed District,
as required by ordinance, nor was a copy of the building
plans as previously presented to the Council available
for inspection. These documents would all have a bearing
on a complete analysis of the situation and should be made
available for review before a final decision is reached by
the Orno City Council.
Violations of the Orno Zoning Ordinance with respect to
set -back, lot coverage and land alteration are herety ack-
nowledged to be covered in other supporting documentation
and are therefore not covered in my analysis.
Utilizing
exhibits
A,B,C
and
L as
reference
documents 1
wish
to
submit
the
following
observations
and comments:
one
EXHIBIT A. PLAN VIEW In addition to identifying the pos-
itions for photographs 1 thru 7, and the cross-section line
of exhibit B, it also illustrates the relationship of both
existing residences and the proposed Podany addition.
1)An apparent reduction of open space is noted, although
a certain amount of this reduction would be allowed
under the present ordinance if the addition is limited
to the existing rear building line on the lake side.
This is also apparent in photo 7 as the addition would
fill the existing opeti space from the Podany home to
the evergreen plantings as viewed when approaching the
Halladay home by car.
2)This same effect will be very noticable as you approach
the parking area of Halladay's as shown in photo 6. The
addition would close the space from the northwest
corner of the Halladay home to the evergreen planting
significantly reducing light penetration and air cir-
culation in addition to affecting the visual quality
of the entrance area.
EXHIBIT B, SECTION LOOKING NORTH This cross-section is
based upon the Cardarelle plot plan and is supplemented
with on-site elevations taken with a fiand level. It
begins to point out an even more serious concern.
1)The existing land form consists of a small hill slop-
ing from the Podany residence side yard down to the
Halladay home. This causes concern with respect to fut-
ure drainage from additional roof area along with
channelizing the existing drainage from the front area
of Podany's which is presently accommocated on the west
side of the hill on Podany's land.
2)This situation becomes more alarming as you observe the
proposed addition being built on top o6 thie eztieting
Land bonm resulting in even further blockage of light
from the southwest and air circulation because of the
proposed building mass.
3)Photos 4,5 and 6 illustrate from various vantage points
the existing hill and slope to the Podany home.
EXHIBIT C, Panoramic view looking from northwest thru south-
west, shown as point C on exhibit A.
1)From a 5 foot eye level a perspective projection of the
proposed addition would result in the building mass shown
graphically in grey tones on the overlay sheet. The dark
grey horizontal area represents the shadow line of the
overhang. This building mass would obviously represent
two
') continued, a considerable intrusion into the lakeshore
open space presently existing from the Podany rear
building line to the left, wo-ich is towards the lakeshore
and would be visible from al of Halladay's windows
on the west side of his home.
2)Photos lA and 1B further show this concern as they are
taken from the den/office room, lA being taken at 90°
to this window and 1B taken from a seated position at
Mr. Halladay's desk looking to the southwest. The entcAe
shy anea shown on the photo would be obliterated as
viewed in IA and all of the sky area in the two wir
dow openings to the right in photo 1B would also be
obliterated.
3)Photo 2, taken from the lakeshore deck which leads
directly from the living and dining areas on the main
level, illuatrates by the grey tone the approximate
building mass as proposed and viewed from this pre-
sently private area, which when built did not antic-
ipate encroachment into the adjacent Podany lakeshore
setback or it would have been designed and located
in a different manner.
In summary, from my viewpoint as a landscape architect and
land planner, the most most serious aspect of the proposal
effecting the Halladay's living environment, is the intrusion
of a subetant.iat buitd.ing mass into a vett' et.tticat anea oA
tight and act cltcutati.on...... this visual and physical
space is presently protected by a very valid lakeshore set-
back requirement, which if allowed to be varied, would
certainly adversely affect the total living environment.
This open apace 6eet.ing was very important to the Halladay's
when evaluating and subsequently purchasing their home.
In my opinion this type of vested i.ntetest should be
respected and protected by the governing body of Orno,
not only with respect to the Halladay's. but for the
long range benefit to all residents of Orno as their
elected representatives.
Re pectfu11 ,
V4
Donald K. Rippel
landscape arch':ect/planner
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CLASSIFICATION OF SOILS FOR ENGINEERING PURPOSES
ASTM Designation: D 2497 — 69 AND D 2488 — 69
(Unified Soil Classification System)
Major divisions symbols
Typical names Classification criteria
a WelI- Waded gravels andw CU= 06o greater than 4;
GW gravel -sand mixtures, little o 2
ij or no fines H C _= /030/ between 1 and 3
8 m Z Dio xDGo
mPoorly graded gravels and
V U GP gravel -sand mixti•res, little Not meeting both criteria for GW
8 ? 15
or no fines v°,
y U
4 C c y V 7
e O ty gravels, gravel -sand- a U g' Atterberg limits below
Sil
0 GM `o tD tD c ''A" line or P.I. less Atterberglimitsplot-
y �.� £ silt mixtures m 3iO j than 4 ting in hatched area
g o r
0 0 m. are borderline classifi-
y m • • • cations requiring use
Atterber limits above
az > GC Clayeygravels, gravel- A•• line with P.I. of dual symbols
sand clay mixtures . . . greater than 7
`o
rn
io
Well -Waded sands and gra- H i > CU = D60 greater than 6;
g 10
SW fines sands, little or no [� m ^ Cz= Di0xoDso between 1 and
5i O xR"i y{. M
mPoorly graded sands and M Z Z o
y U SP gravelly sands, little or no a N R Not meeting both criteria for SW
$ • fines N 8 $ Z
15 Z
a �' Atterberg limits below
a Silty sands, sand -silt mix- jb A^ line or P.1. less
c SM tures ££ Atterberg limits plot-
8 than 4 ting in hatched area
are borderline classifi-
3 cations requiring use
Atterberg limits above of dual symbols
Sc Clayey sands, sand -clay •'A•' line with P.I.
mixtures greater than 7
Inorganic silts, very fine Plasticity Chart
ML sands, rock flour, silty or 60
clayey fine sands
N
� o
For classification of fine rained
soils and fine fraction of coarse -
Inorganic clays of low to 50 grained soils.
medium plasticity, gravelly Atterberg Limits plotting in CH
i _ CL clays, sandy clays• silty hatched area are borderline
N E clays, lean clays classifications requiring use of
N x 40 dual symbols.
e } Organic silts and organic Equation of A-line.
L OL silty clays of low plasticity PI 0.73 (LL -20)
30
O U
Ali O ..
2
N Inorganic silts, micaceous _A
Ln MH or diatomaceous fine sands rs
m or silts, elastic silts 20
Qe £
E d
L
Inorganic clays of high 10
CH plasticity, fat clays
r 7
E 4
in =
V Organic clays of medium to 00 10 20 30 40 50 60 70 80 90 100
a OH high plasticity
J
Liquid Limit
> U w Peat, muck and other hi 1
E — Pt 47h V
organic soils *Based on the material passing the 3 in. (76 nen) sieve.
= 5
=
6
1170 -Ai
SE -
I
OH and
MH
,•P
�
CL
C
L - ML
ML and OL
II
PHONE 612/645.3601
TWIN CITY TESTING AND ENGINEERING LABORATORY, INC.
PROJECT:
REPORTED TO:
ENGINEERS AND CHEMISTS
662 Cromwell Avenue - St. Poul, Minnesota 55114
REPORT OR: WATER S_H_EU INVESTIGATION
ED PODANY RESIDENCE
3285 CARMENS BAY DRIVE DATE:
MINNETONKA,_MIN_NESOTA _
Mr Ed Podany `^ y FURNISHED BY:
3285 Ca rmerls Bay Drive COPIES To: 6 )
Minnetonka, MN 55343
LABORATORY No. 9-5984
March 7, 1975
Anderson Builder
Attn: Mr Keith Anderson
INTRODUCTION!
This report concerns the recent inspection we performed of the soil conditions and site
topography at the above referenced project Our work was performed at the verbal request
of Mr Keith Anderson of Anderson Builders Inc.
We understand the site is presently occupied by a two-story residence with a walkout
basement and attached garage. We further understand that an addition is proposed for
the existing structure. The approximate dimensions of the addition would be on the order
of 20' x 30'. In this regard, problems were encountered in obtaining a buildinq permit
as the new roof area upsets the ratio of grassed (absorptive area) covered area in the
control of surficial runoff As the site is located on Lake Minnetonka, concern has been
expressed regarding the increase in the amount of sediments carried into the lake by
surficial runoff. Therefore, the purpose of our investigation was to determine the soil
conditions existing on the property and to construct a topographic map of the lot area.
Then, utilizing the results of our investigation, alternate procedures were to be con-
sidered for the control of lot drainage
FIELD INVESTIGATION PROCEDURES
On March 4, 1975, we performed our investigation of the site. Our investigation con-
sisted of construction of a topographic map as well as placing a 29' deep soil boring to
aid in determining the subsurface soil conditions
Soil Sampling
One boring was put down at the location indicated on the attached topographic map, wit,I
a 6" power auger and only disturbed samples were recovered Because of this method, our
determination of the depth and extent of the various layers of soil and the consistency
of cohesive soils are only approximate
As the samples were obtained in the field, they were visually and manually classified
by the crew chief in accordance with AS1M�D2488-69. Representative portions of all
samples were then returned tc the laboratory for further examination and for verification
of the field classification. A log of the boring indicating the depth and identification
of the various strata, water level inforriat ion and oertinent information regardinq the
method of maintaining and advancing the drill holes are attached. Charts -.11ustratinq
the soil classification procedure, descriptive terminology and symbols used on the borinq
log is also attached
AS AMUTUAL PROTECTION TO CLIENTS, THE PUBLIC AND OURSELVES ALL REPORTS ARI SUBMITTSO A, THE CONFIUEN/YAL PROPERTY OF CLIENT.. AND AUTHOR
IIA TION FOR PUBLICATION OF STATEMENTS. CONCLUSIONS 00 EXTRACTS $'ROM OR REUAROING OUR REPORTS 10 *(NERVED PENDING. OUR IRRITTEN APPROVAL
645-3601
TWIN CITY TESTING AND ENGINEERING LABORATORY, INC,
REPORT OF:
LABORATORY No. 9-5984
ENGINEERS AND CHEMISTS
662 Cromwell Avenue - St. Paul, Minn. 55114
The site is a residential lot and
southern end of the lot, where a
Minnetonka below. As previously
garage with a walkout basement.
WATER SHED INVESTIGATION
SITE CONDITIONS
DATE: March 7, 1975
PAGE. 2
slopes gently toward the south except at the extreme
near vertical face drops approximately 30' to Lake
stated, the site is now occupied by combined house and
SOIL. CONDITIONS
The soils encountered were lean and sandy clays to the depths of our boring These soils
are generally typical of the Lake Minnetonka area and are not conducive LG the absorption
of surficial runoff. That is, precipitation falling on the existing lot would normally
fcilow the tupography and move directly to Lake Minnetonka with very little water actually
being absorbed by the grassed areas.
ANALYSIS AND RECOMMENDATIONS
One method of controlling surficial drainage, which allows for the water to be returned
to the groundwater system with minimal sedimentation, would be the installation of a French
drain. This system consists of an excavation filled with clean granular material, which
allows for surficial, runoff to be returned to the groundwater system while filtering out
any sediment. However, this system would only be effective if connected to moderately
permeable to permeable soils as opposed to the generally impervious (cohesive) soils
encountered at the site.
As the soils encountered at the site are cohesive, an alternate type of drainage system
will have to be employed The use of a collection settling pond with an underlying drain-
age trench system would appear to be the most practical approach from the standpoint of
useability of the lawn area. With thissystem,the rear lot area would be contoured to
a low swale to prevent the majority of the surface water runoff from draining directly
to the lake. Then a series of sand filled trench containing perforated drain tele would
be placed across the Swale with the pipes daylight)ng on the steep vertical face to the
south The Swale and trench system would then be landscaped with a sandy topsoil as
opposed to the cohesive material presently on the site. The sand topsoil and sand filled
trenches would then drain and filter any water trapped within the swale area. The size
of the Swale and number and dimensions of the underlying trenches would have to be based
on such parameters as annual rainfall and vulumes of water directed to the ponding area
Therefore, a competent engineering hydrologist f!rm, familiar Nith municipal drain
fields and other related water, problems, should be contacted for the design of this system
or other such systems adaptable to this structure.
REMARKS
The recommendations and suggestions contained in this report are our opinions based on the
data which are assumed to be representative of the site explored, but because the area of
AS AMUTUAL PROTECTION TO CLIENTS. THE PUBLIC AND OURBELVEE. ALL RC►ORTS ART SUBMITTED AS TNR CONFIOENTIAL PROPERTY OF CLIENTS. AND AUTHOR
IZA TION FOR PUBLICATION OF STATEMENTS, CONCLUSIONS 00 EETRACTS FROM OR REGARDING OUR REPORT■ IB Rl SERvED PFNDING OUR WRITTEN APPROV11
645-3601
TWIN CITY TESTING AND ENGINEERING LABORATORY, INC.
ENGINEERS AND CHEMISTS T 662 Cromwell Avenue - St. Paul, Minn. 55114REPORT OF: WATER SHED INVESTIGATION
DATE: March 7, 1975
LABORATORY No. 9-5984 PAGE. 3
REMARKS
(cont.
the boring in relationship to the entire area is very small, and for other reasons, we do
not warrant conditions below the depths of our boring or that the strata logged from our
boring are necessarily typical of the entire site
TWIN CITY TESTING AND
ENGINEERING LABORATORY INC
Ralph L Anderson
Geologist
Thomas K Smith, P.E.
RLA/TKS/rs
AS A MUTUAL PROTECTION TO CLIENTS, THE PUSLIC AND OURSELVES. ALL. REPORTS ARE SUBMITTED AS THE CONFIDENTIAL PROPERTY OF CLIENTS, AND AUTHOR.
IEATION IOP PUBLICATION OF STATEMENTS. CONCLUSIONS OR EXTRACTS FROM OR REGARDING OUR REPORTS IS RESERVED PENDING OUR WRITTEN APPROVAL
TWIN CITY TESTING AND ENGINEERING LABORATORY, INC.
LAKE MINNETONKA
Approximate Elevation 62'
Pot'any Pronn;'i'
Contour Interval ? 1/2'
SOIL TEST eoRIWA I.,oe NO. y �
scaLE: /vo
DRAWN BY
0
CHECKED 8V TE
Twin City Testing and Engineering Laboratory, Inc.
JOB NO. VERTICAL SCALE 1 It = 4 LOG OF TEST BORING NO. 1
PROJECT nRAINAGE PRnRIEM� 3285 r.OMMONS BAY ROAD, LAKE MINNETONKA, MINNESOTA
DEPTH
DESCRIPTION OF MATERIAL
SAMPLE
LABORATORY
TESTS
FIN
EET
f—SURFACE ELEVATION 95. $' _
N
WL
NO.
TYPE
W
D
L. L.
Ou
LEAN CLAY,black, frozen to ;' (CL)
1
FA
i
LEAN CLAY, a little gravel,
brown, medium (CL)
2
FA
4
SANDY CLAY, a little gravel,
brown to grayish brown, rather
$tiff to stiff (CL)
3
FA
4
FA
5
FA
i
I
6
FA
I
I
i
7
FA
i
29
End of Boring
WATER LEVEL MEASUREMENTS
START 3-4-75 COMPLETE 3-4-7
DATE
TIME
SAMPLED
DEPTH
CASING
T
CAVE-IN
DEPTH
BAILED DEPTHS
WATER
LEVEL
METHOD 6 FAO-29 ,a 2.35
2o5D
29
i
t0
----
CREW CHIEF Mtshler
t0
to
`
t0
GENEML NOTES
See attached data sheet and/or graph
WATER LEVEL
SYMBOL —'W
Water levels shown on the boring logs are the levels measured in the borings at the time
and under the conditions indicated. In sand, the indicated levels can be considered
reliable ground water levels. In clay soil, it is not possible to determine the ground
water level within the normal scope of a test boring investigation, except where lenses
or layers of more pervious waterbearing soil are present and then a long period of time
may be necessary to reach equilibrium. Therefore, the position of the water level symbol
for cohesive or mixed texture soils may not indicate the true level of the ground water
table. The available water level information is given at the bottom of the log sheet.
DENSITY
TERM
Very loose
Loose
Medium Dense
Dense
Very Dense
DESCRIPTIVE TERMINOLOGY
"N" VALUE
0-4
5-8
9-15
16-30
Over 30
CONSISTENCY
TERM "N" VALUE
Soft
Medium
Rather Stiff
Stiff
Very Stiff
0-4
5-8
9-15
16-30
Over 30
Standard "N" Penetration: Blows per foot of a 140 pound hammer failing 30 inches on a 2 inch OD split spoon.
RELATIVE PROPORTIONS
TERM
Trace
A Little
Some
With
PARTICLE SIZES
Boulders
G ra ve I
Coarse
Fine
Sand
Coarse
Medium
Fine
Silt and Clay
Note: Sieve sizes shown are U S. Standard
SE -4(70A)
RANGE
0-5%
5.15%
15-30`6
30-50%
Over 3"
ai-3'
114-'4..
#4-#10
1110-1140
440-#200
Determined by plasticity
Characteristics
DOLLING & SAMPLING SYIII111110ILS
LABORATORY' TEST SYIWLS
svrOl
DEFINITION
SYMBOL
DEFINITION
C.S.
Continuous Sampling
W
Moisture content - percent of dry weight
P. D.
2-3/8" Pipe Drill
D
Dry density-poundS per cubic foot
C.O.
Cleanout Tube
LL, PL
Liquid and plastic limits determined in
31A HSA
3%" I.D. Hollow Stem Auger
accordance with ASTM D 423 and D 424
4 FA
4" Diameter Flight Auger
Qu
Unconfined compressive strength -pounds per
6 FA
6" Diameter Flight Auger
square foot in accordance with ASTM D2166-66
2'/i C
21h" Casing
4C
4" Casing
Additional insertions in Ou column
D. M.
DriIIingMud
Pq
Penetrometer reading-tons/square foot
J. W.
Jet Water
Ts
Torvane reading -tons 'square foot
H. A.
Hand Auger
G
Specific gravity - ASTM D 854-58
NXC
Size NX Casing
SL
Shrinkage limit - ASTM D 427-61
BXC
A XC
A2"
Size BX Casing
Size AX Casing
PN
Hydrogen ion content -meter method
SS
O.D. Split Spoon Sample
O
Organic content -combustion method
2T
2" Thin Wall Tube Sample
M.A.'
Grain size analysis
3T
3" Thin Wall Tube Sample
C.
One dimensional consolidation
Qc'
Triaxial compression
See attached data sheet and/or graph
WATER LEVEL
SYMBOL —'W
Water levels shown on the boring logs are the levels measured in the borings at the time
and under the conditions indicated. In sand, the indicated levels can be considered
reliable ground water levels. In clay soil, it is not possible to determine the ground
water level within the normal scope of a test boring investigation, except where lenses
or layers of more pervious waterbearing soil are present and then a long period of time
may be necessary to reach equilibrium. Therefore, the position of the water level symbol
for cohesive or mixed texture soils may not indicate the true level of the ground water
table. The available water level information is given at the bottom of the log sheet.
DENSITY
TERM
Very loose
Loose
Medium Dense
Dense
Very Dense
DESCRIPTIVE TERMINOLOGY
"N" VALUE
0-4
5-8
9-15
16-30
Over 30
CONSISTENCY
TERM "N" VALUE
Soft
Medium
Rather Stiff
Stiff
Very Stiff
0-4
5-8
9-15
16-30
Over 30
Standard "N" Penetration: Blows per foot of a 140 pound hammer failing 30 inches on a 2 inch OD split spoon.
RELATIVE PROPORTIONS
TERM
Trace
A Little
Some
With
PARTICLE SIZES
Boulders
G ra ve I
Coarse
Fine
Sand
Coarse
Medium
Fine
Silt and Clay
Note: Sieve sizes shown are U S. Standard
SE -4(70A)
RANGE
0-5%
5.15%
15-30`6
30-50%
Over 3"
ai-3'
114-'4..
#4-#10
1110-1140
440-#200
Determined by plasticity
Characteristics
WILLIAM D. SCHOELL
CARLISLE MADSON
JACK T. VOSLER
JAMES R. ORR
HAROLD E. DAHLIN
LARRY L.HANSON
RAYMOND J. JACKSON
WILLIAM J. EIREZINSKY
JACK E. GILL
FRANK V. LASKA
Anderson Builders
3900 Leslee Curve
Excelsior, MN 55331
SCHOELL & MADSON, INC.
ENGINEERS AND SURVEYORS
7601 • 50 NINTH AVENUE SOUTH • HOPKINS. MINNESOTA 55343
April 3, 1975
Attention: Mr. Keith Anderson
Subject: Storm water Runoff, Lot 7, Block 1
of Carman's Cove, Orono,
Our File Fo. 8636.
Gentlemen:
As requested, we have studied various methods of im-
proving the quality of runoff on the subject property in
compliance with Lake Minnetonka Conservation District Guide-
lines. We consulted with the Engineers for the Minnehaha
Creek Watershed District and Frank Mixa, the Director of
Lake Minnetonka Conservation District in preparation of this
report. Both these authorities indicated their approval of
the -recommendations contained herein.
The LMCD Guideline Policy Statement limits the imper-
vious area of any lot to 25 percent of the land lying beyond
50 feet, but within 250 feet of the lakeshore, unless adequate
measures are taken to enhance the quality of runoff. Using
the survey prepared by Cardarelle & Associates, Inc., we calcu-
late the total lot area beyond 50 feet to be 12,550 square feet.
The impervious area would thus be limitE!d to 3,137 square feet.
The proposed 1,120 square foot addition to the existing two-
story residence will increase the total impervious area including
roof area and driveway to 4,800 square feet, or 38 percent.
We recommend the use of a settling pond with a permeable
berm outlet as the most practical solution of improving the
quality of runoff. The pond would be constructed by grading a
Swale in the rear lot area. The runoff from the entire im-
pervious area as well as approximately 5,400 square feet of
lawn area would drain to this ponding area and outlet to the
lake through a pervious berm.
The recommended berm section is as shown on the attached
detail. The lcuer eight inches of the berm is sp�cifieri to
be 1/4 inch fine filter aggregate. Larger aggregate <erould
SCHOELL & MAOSON.INC.
Anderson Builders Page 3
April 3, 1975
711eiCRLs- BERM QgTAIL
E;CAZc /^' = .2, Vert
of ; I/ / yPrl Z.
7
McCOMBS-KNUTSON
ASSOCIATES, INC.
CONSULTING ENGINEERS G LAND SURVEYORS A SITE PLANNERS
April 18, 1975
Mr. Walter R. Benson
Village Administrator
Village of Orono
P. O. Box 66
Crystal Bay, Minnesota
Subject: Martin Podany
3285 Carmen Road
Dear Mr. Benson:
We have reviewed the data you have submitted on the
subject project. In our review we have placed particular
emphasis to the Engineering Report submitted by Schoell
& Madson, these soil borings conducted by Twin City Testing
and data submitted by Norman K. Rippel, Landscape Architect
Planner. In reviewing this soil data submitted by Twin
City Testing a type of trench drainage system is suggested
for disposing of the water originating on the hard cover
area. This was just a suTr3nary suggestion no details were
given and it was not considered by the report submitted
by Schoell & Madson. Schoell & Madson proposed the construction
of a settling pond with a pervious dike so that the water
would be settled in the pond, perculate through the dike
and drain into the lake. We have some uncertainty as to
what the Engineer is referring to at the "rear of the lot".
However, from his sketch it appears he is referring to
the area between the house and the lake. This being the
case the pond would be located between the house and the
lake.
12805 OLSON MEMORIAL HIGHWAY. MINNEAPOLIS, MINNESOTA 55441 TELEPHONE !612) 5453735
36 NORTH MAIN STREET, HUTCHINSON, MINNESOTA 55350 TELEPHONE 1612' 897-8031
SOUTHWEST ENGINEERING DIVISION. MARSHALL, MINNESOTA 56258 TELEPHONE (507) 532-5820
We concurr that water discharged into the holding
pond and perculating thru a 14 foot long pervious soil
would be of at least as good a quality as runoff from the
present lawn area. So as long as the pond would operate
efficiently no deterioration of the water reaching the
lake would occur as a result of an additional hard cover.
However, a pond of this magnitude with a 8 inch thick coarse
layer would we think be and impractable and difficult system
to maintain in satisfactory operation. It would seem to
us that to keep this pervious layer to operating efficiently
there would have to be a continually cleaning of the entrance
to the filter. This would mean that it would require maintenance
to prevent the growth of any grasses, or weeds, it would
require frequent cleaning to inslire no deposition of grass
clippings, leaves or other debris from building up or causing
plugging of the filter layer. It would also seem that
in order to function properly a flooding of the ponding
area is going to be required and that after a very short
period of time the bottom of the filter area would become
contaminated or plugged causing water to be ponded in this
area for an extended length of time rather than the 1-2
hours suggested in the report a few inches deep but it
would be a real deterrent to maintain a yard and a source
of breeding for mosquitos and ether unsightly conditions.
We also cannot determine -crom the information submitted
exactly where this ponding area is proposed but it appears
from looking at the site that it would entail a major portion
of the balance of the present level land between the house
and the lake. If it is to be constructed towards Carmen
Road and the house then major difficulties would be encountered
with the grading of the site to carry the water into this
area and then to getting rid of the water which seeps through
the dike.
Summinq up we conclude that with a proper operating
system as proposed could provide water of at least equal
quality to that present discharge from the draft surface.
However, major problems appear to exist in the successful
sustained long term operation of the system proposed and
we believe it would require extensive maintenance and it
would soon be discarded or otherwise .ignored. For this
reason we do not believe that a long range solution to
the water quality problems have been provided and would
reserve final judgment until such time as additional
supplimentary data is submitted showing detail data
dimensions and location. Further the soil test seem
to preclude the construction of any system which would
feed the water back into the ground water table as the
soils are rather impervious and such a solution does
not appear practible.
Our review has not attempted to address itself
specifically to the items raised by Mr. Ripple regarding
the effect on the light and air circulation. However,
the visual changes referred to in his report appear
accurate. However, we have not seen the detailed plans
on the proposed house and would have to reserve absolute
judgement until such plans our available.
If you have any further questions or desire further
comments regarding this project do not hesitate to contact
US.
Very truly yours,
MCCOMBS-KNUTSON ASSOCIATES, INC.
William H. McCombs, P.E.
WHM:j1