7.3. SR 05-31-1994
rl! -\.(
( II
!Ik River
ITEM 7.3.
MEMORANDUM
TO:
MAYOR AND CITY COUNCIL
FROM: STEPHEN ROHLF, BUILDING
AND ZONING ADMINISTRATOR
DATE: MAY25,1994~ Po4/'
SUBJECT: ENVIRONMENTAL ASSESSME~
WORKSHEET (EAW) FOR COUNTRY
CROSSINGS
At the May 23, 1994, City Council meeting, you received a copy of the EA W
for Country Crossings, comments on the EA W from various governmental
agencies, and a copy of a draft resolution. In the resolution staff responds to
the comments received on the EAW. It is important that the Council
understands these responses and incorporates them into the approvals for
the various phases of this project.
e
One comment of special significance was a made by both the Minnesota
Pollution Control Agency (MPCA), and the Department of Natural Resources
(DNR). That comment was in regards to the quality of run-off from the site
that enters Lake Orono. The original grading and drainage plan for all
phases of the project had all run-off being filtered through sedimentation
ponds with the exception of approximately 13 acres of the first phase. The
developer is proposing a revised grading and drainage plan so that all storm
water is filtered through sedimentation ponds to aid water quality.
In order to accomplish this, an additional pond will need to be created. The
developer is proposing to create this pond on the east side of the park land in
the plat (see attached map). Terry Maurer, and John Bogart of John Oliver
and Associates, will be at Tuesday night's meeting to explain the technical
aspects of the location of this pond.
e
Staff feels that the issue of water quality in Lake Orono is important enough
that this pond should be created. Staff is recommending the Council approve
the creation of this pond, but that no significant trees be allowed to be cut.
With this, and the other environmental issues addressed (according the
resolution), the staff is recommending that the Council pass the resolution
provided to them, declaring that the preparation of an Environmental Impact
Statement for this project is not necessary.
cc-envir/council
P.o. Box 490 · 13065 Orono Parkway · Elk River, MN 55330 · (612) 441-7420 · Fax: (612) 441-7425
"- I'''' -T'
~ ,
*
..iIf' " .
h -
"', -T'
cr>',
'"' ',--X- -"
x '"
~ '"
." -, ,.,
," ~ \ 'J ,
'"
0.. -.,..,
~,,/
'" ,.,
'"
aN '.'
,--
-x-~_.. '.-
--.
,
r-,
/'-' '-'
, "
"" \ J " ,
'" t
W'
, ... ,
i ,
J
" ~ r, /
'" '" / /
E' n
;.. ." r ,I
x (
'"
~\ ~ i
x Q /-
"""c"<~-X-
, ,
x \ )
I V
@
~
-.~
'.~~
~."!-
"'''' ,.... - r... A r....- r... I -,- I ,... . I
-< "I" I I I \ I I I t I I I I I I \ I
...... I \ L'" . ,-, L..... ...", I f I ,... I ,
{;~~
(\7.0
~tl~
o "^
2- ~
~ v.
I~
Ol(')
010
=Z
:;oZ
(')f'TI
"U(')
>-1
..-I
.....0
o
"'m
3x
Vi
-I
Z
G)
e
-i
-<
"
; - .~; ::.,_:.~~ ~
,. ~ '-;.<~-',
:,.:}';~;~J.:~:~~~tl~:,
:s,' (;;~~~:1j~~;
..;:'~~:;:.;'i.;;'_\:
'i:;t~r:
-.'--.'_.r_..~_Z:
.' ',' .';;"'~-
,.,
'J ...
,-,
'... -'"
, "
,. .
-T'
"
. ,':-'-'
.-.>
. .~;-'
,.,
, ,
05/:31/94
15:55 FAX 612 441 5665
JOHN OLIVER ASSO
~001
e
Civil ElIginftrbag
Land Sl.tn'eying
und P'411njllg
John Oliver & Associatesl Inc.
SID Dodge AWlmue, m RMr, MN SSJ3D
(61%) 441-~07~ . F4.JC 441-$66$
May 31, 1994
Steve Rohlf
city of Elk Ri~er
13065 orono parkway
Elk River, .MN 55330
Re: EAW for Lakoduk site
Dear Mr. Rohlf,
Per your request we have conducted a preliminary analysis to determine what
potential impacts the proposed development might have on the water quality of
Lake orono.
The sedimentation ponds proposed should remove most of the particulate matter
above 5 microns in size. Nurp ponds typically remove approximately 90% of 5
micron sized particles for ponds with surface areas of o. 8~ residential areas and
1. 7% commercial areas respectively. The ponds as designed represent 2.43% of t.he
total residential area. The commercial area ponds are not yet designed but will
be meeting this criteria.
other common stormwater pollutants have the following reductions at the 90\
removal.
e
Lead and copper: 77% removal
COD, BOD,
soluble and
total phosphorus,
Nitrates and zinc: 54% removal
Organic Nitrogen: 36'
This information comes from Stomwa't.er Wet Detention pond Design for water
Quality Benefits, 1994, Robert pitt Pb..o, Lewis ~lishers.
We also examined the relative impact to the lake in ter.m.s of i't.s total watershed.
please see the attached analysis. ~he total increase in total phosphorus is
slightly more than 0.04% but with a slightly decreased residence time in the lake
due to the increased volume of runoff proposed to reach the lake. The result is
no significant increase in chlorophyll-A which of course is an indicator of
nutrients reaching the lake.
Based on this info:r:mation we feel that we can say that there will be no
significant impact to the water quality of Lake orono.
Sincerely,
th~
U: Tony Emmerich
e
file: 6719-05
i
05/31/94 15:55 FAX 612 441 5665
JOHN OLIVER ASSO
141 002
.
Minnesota LakE Eutrophication An~lY5is Procedure
ENTER INPUT VARIABLES
LAKE NAME ? ORONO PROPOSED
ECDREGION NUMBER 1ENLF,2=CH~,3=~CP,4=NGP ? 2
WA '"ERSHED ~f:':EA (HA) ? 140~.83
LAKE SURFACE AREA (HAl ? 113.7
LAKE MEAN DEPTH (M) ? 5
OBSEF.:VED MEAN LAI<E TP (ljI3/L:) .(. 130
OBSERVED MEAN CHL-A (UG/L) ? 18
OBSERVED MEAN SECCHI CM) ? 0.7
INPUT DATA~
LAKE NAME =Of':ONO F'f":QPOSED EC:O~~EI3 I ON;;CHF
LAKE AREA = 113.7 HA
WATERSHED AREA (EXCLUDING LAKE) = 140683 HA
MeAN DEPTH = 5 METERS
OBSERVED MEAN TP = 130 UGiL
OBSERVED MEAN CHL-A = 18 UG/L
OBSERVED MEAN SECCHI =.7 METERS
<press ENTER to view yesults>
LAKE = ORONO PROPOSED ECOREGION = CHF
AVERAGE INFLOW TP = 148.1497 UG/L TOTAL P LOAD = 27101.52 KG/YR
LAKE OUTFLOW ~ 182.9~34 HM3/YR AREAL WATER LOAD - 1~O.B913 M/YR
e RESIDENCE TIME == 3.107E.8'3E-02 YF:S F' RETENTION COEF =.1'35853'3
VARIABLE UNITS OBSEfO:'"JED F'F.:EDICiED STD ERRO~~ F~ESIDUAL T-TEST
TOTAL P (UG/L) 130.00 119.13 24.11 0.04 0.33
CHL-A (UG/L) 18.00 70.99 32.79 -0.60 -2.57
SECCHI (METERS) 0.70 0.63 0.21 0.05 0.30
NOTE= RESIDUAL = LOGI0COBSERVED/PREDICTED)
T-TEST FOR SIGNIFICANT DIFFERENCE BETWEEN OB8. AND PREDICTED
3(~
51:}
CASE A =
CASE B e
CASE C -.
CHLOROPHYLL-A INTERVAL rREQUENCIES (%)
CHL-A PREDICTED PREDICTED PREDICTED
PPB OBSERVED CASE A CASE B CASE C
10 83.78 99.99 99.98 99.60
20 32.25 99.18 98.66 95.12
i~. 59 '~4. 01 '~2. 45 85.8E.
0.30 54.46 54.13 53.10
hi I TH I N- YEAF~ VAF.: I AT I ON CONS r DEr.::ED
WITHIN-YEAR + YEAR-TO-YEAR VARIATION CONSIDERED
CASE B + MODEL ERRDR CONSIDERED
PYESS any key to continue
e
05/31/94 15:55 FAX 612 441 5665
JOHN OLlv~R ASSO
I4J 003
. . .
e
Minnesota Lake Eutrophication Analysis Procedure
ENTER INPUT VARIABLES
LA~(E NAME '7-' DF.:OI'l./O
ECOREGION NUMBER I~NLF,2=CH'~3=WCP,4=NGP ? 2
WATERSHED AREA (HAl ~ 140623
LAKE SURFACE AREA (HA) ? 113.7
LAKE MEAN DEPTH CM) - 5
OBSERVED MEAN LAKE TP (UG/L) ? 130
OBSERVED MEAN CHL-A (UG/L) ? 18
OBSERYED MEAN BEeCHI (M) ? 0.7
INPUT DATA~
LAKE NAME =ORONO ECOREGION=CH~
LAKE AREA = 113.7 HA
WATERSHED AREA (EXCLUDING LAKE) = 140523 HA
MEAN DEPTH = 5 METERS
OBSERVED MEAN TP = 130 UG/L
OBSERVED MEAN CHL-A = 18 UG/L
OBSERVED MEAN SECCHI =.7 METERS
(press ENTER to view results)
LAKE = ORONO
AVERAGE INFLOW TP = 148.1497 UG/L
LAKE OUTFLOW -~ 182.8554 HM3/YR
e RESIDENCE TIME = 3. 1(I'~/()14E-02 YRS
ECOREI3 I ON = CHF
TOr AL F' I_O~D
Ar;~EAL WA TEF~ LOAD
F' F~ETENT I ON C:OEF
= 27089.97 KG/YR
= 150. 8227 M/YF~
- . 1'~58'~(l3
3~~. 78
0.21
F.:ES r. DUAL
0.04
-0.50
1). (l5
T-TEST
'v'AF.:IABI_E UNITS OBSEF.:'y'fD PF.:EDr.CTED STD EHF.:OF.:
TOTAL F' (U13/L) 130. 00 11'~. 1~ 24.11
CHL-A (UG/L) 18.00 70.99
SECCHI (METERS) 0.70 0.E3
NOTE: RESIDUAL = LOG1(l(OBSERVEDiPREDICTED)
T-TEST FOR SIGNI~ICANT DIFFERENCE BETWEEN OBS. AND PREDICTED
0.3.;1-
-2.57
0.3(1
C:HLOJ;~OPHYLL-A INTEF~VAL FF~EQ.UENCIES (%::
CHL-A PF.:EDICTED PREDICTED PREDICTED
PPB OBSERVED CASE A CASE B CASE C
10 83.78 99.99 99.98 99.60
20 32.25 99.18 98.65 35.12
30 9.59 94.00 92.45 85.85
60 0.30 54.46 54.12 53.10
CASE A = WITHIN-YEAR VARIATION CONSID~RED
CASE B = WITHIN-YEAR + YEAR-TO-YEAR VARIATION CONSIDERED
CASE C - I:A8E B + MODEI_ ERROR CONSIDERED
PrESS a~y key to continue
e