1981-07-09_GENERAL DOCUMENTS - C1981017

• Permit No: C1981017
• IBM Index Class Name: General Documents
• Doc Date: 7/9/1981
• Doc Name: Bid Documents ‎(IMP)‎
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

STATE Of COL OF+Af)(-) Nit IIAW) f IV
6EPARTMENT OF NATURAL RESOURCES
�. Monte Pascoe,Executive Director
NI-NED LAND REACTAMA'riliop
f�23 Centennial Building, 1313 Sherman Street
- — �— Denver, Colorado 80203 Tel. [phone]
David C. Shelton
Director
July 9, 1981
Mr. Doug Bowman
Mid-Continent Resources, InG.
P.O. Box 158
Carbondale, Colorado 81623
Re: Vegetation Sampling - proposed Coal Canyon Mine
Dear Doug:
The Division has reviewed the proposed vegetation sampling program submitted
by Western Resource Development and has the following comments:
1) On page 1, map scales a�e proposed to be between 1" = 400-700' . Map scales
for the permit area must be nolarger than 1" = 500' .
2) Also on page 1, it is stated that reference areas will he selected
following completion and analysis of the cover data. Cover, production, and woody
plant density should all be considered when selecting a reference area, in order
to increase the probability l f selecting a comparable reference area.
' 3) On page 2, the comparabi itu statistic should be:
.Xf - X2I < t S + S 2
N 1 N2
where S1 and S2 are the pool d variances since smaple sizes may not be equal.
4) On page 3 under samplingladequacy, it is shown that a two-tailed t-test
with 80% confidence will be used. The Division wants to empahsize that 80%
confidence is for woody plant communities and 90% confidence must be used for
herbaceous communities.
5) Western Resource Development proposes to use a 1 meter by 2 meter quadrat
for determining herbaceous production. In woody plant communities with sparse
herbaceous understory, which are frequently encountered in the general area
of the proposed Coal Canyon �ne, the Division recommends using a 1 meter by
5 meter quadrat. The amount of clipping required is generally no more than
clipping a quadrat one-tenthlthat size in a herbaceous community. The greatest
advantage of clipping a 5 m2 quadrat is that variability among sampling points
is reduced, therefore, reducing the number of samples required to meet sampling
adequacy, and producing a mo e accurate estimate of the mean and standard deviation.
6) On page 3, it is stated that cushion plants and noxious plants will not be
clipped. Noxious weeds shou4d be clipped and weighed as a separate group,
and such cushion plants as phlox should be clipped where plant height exceeds
1 cm.
7) Since the Division has n set policy on species diversity, it is recommended
that this determination be pLtponed until Division policy is set. Since cover
data by species will be coll cted, sufficient information will be present to