ML19259A581

Forwards Environ Mitigation Plan-Big Thicket Transmission Corridor Crossings in Response to Request.Plan Describes Removal & Restoration of Vegetation at Power Transmission Corridors Thru Big Thicket

ML19259A581
Person / Time
Site:	05000510, 05000511
Issue date:	10/26/1978
From:	Humphreys L GULF STATES UTILITIES CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
BHG-1522, NUDOCS 7901080115
Download: ML19259A581 (16)

Text

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l , ;J POST OPF1CE BOX A R EA 2951 COD E

• BEAs M ONT, 7 t 3 838 663 1

[a TF XA S 777O October 26, 1978

,- BHG - 1522 File Ilo. G1.01.9 Mr. Harold R. Denton, Acting Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Case:

Blue Hills Station Docket Nos. 50-510, 50-511 Big Thicket Mitigation Plan For your information and as requested by the Staff, enclosed please find three copies of Gulf States' Environmental Mitigation Plan pertaining to transmission line crossings of the Big Thicket National Preserve. This plan was prepared and submitted to the Department of the Interior in accordance with the agreement reached at our joint meeting on March 6, 1978. A copy of the submittal letter is alsa attached.

Very truly yours, L. L. Humphreys Senior Vice President Energy Develcpment TMP/mb Enclosures p ,

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10th floor Nuclear files / Nuclear f Petroleum Bldg Real Estate Files GULF STATES UTILITIES COMPANY POST OPFICE DOX 2951 . OEAUMONT. TE MA S 77704 A REA CODE 7 13 83a.663 i September 22, 1978 Mr. Thomas E. Lubbert Superintendent Big Thicket National Preserve P. O. Box 7408 Beaumont, Texas 77706

Dear Mr. Lubbert:

TRANSMISSION LINE CROSSINGS OF BHG NO. 1521 THE BIG THICKET NATIONAL PRESERVE FILE NO. N29.18 In accordance with those understandings reached at our March 6, 1978, meeting with the Department of Interior and attended by representatives of the Nati'onal Park ,

Service and Nuclear Regulatory Commission and our letter of March 17, we are enclosing six copies of the Environ-mental Mitigation Plan we agreed to furnish. covering the three 500 KV transmission line crossings of.'the Big Thicket Preserve.

We would appreciate your review of this plan and advising us of your approval, together with appropriate notices to -

other interested parties, so that we may proceed with the

, implementation of same.

Yours truly, Originoi signed By .

. E. Bondumnt ,

.. E. Bondurant oenior Vice President JRC:ms Attachments i

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3 ENVIRONMENTAL MITIGATION PLAN BIG THICKET

TR ANSMIS SION CORRIDOR CROSSINGS i '

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ENVIRONMENTAL MITIGATION PLAN BIG THICKET TRANSMISSION CORRIDOR CROSSINGS INTRODUCTION This document sets forth Gulf States' plans for removal and restor-ation of vegetation at three proposed power transmission corridors to be constructed through portions of the Big Thicket Preserve. The primary objectives during construction are to preserve as much vegetation as possible and develop a plant community that will be relatively mainte-nance free for periods of 3-5 years, The three crossings, identified as Lines 531, 547 and 560 are shown as they relate to the Preserve in Figure 1. Lines 531 and 547 transect the Preserve at separated points along the Neches River Corridor. Line 560 transects the Preserve at the Little Pine Island Bayou Corridor.

Any future required crossings of the Preserve for high voltage trans-mission lines will be made immediately adjacent to these crossings.

• To accomplish the stated objectives requires consideration of several important factors: 1) the profile of the lines as they cross the Preserve which determines allowable vegetation heights, 2) how much crown may be removed without tilling the tree 3) regrowth rates of crown and ground vegetation following disturbance which varies with site, vegetation type, and the nature of the disturbance, 4) the types of vegetation that will have to be planted to restore cleared areas, and 5) the control of access to the transmission towers to allow for maintenance and future line improvements.

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GENERAL DISCUSSION Attached as Figures 2, 3 and 4 are the alignment maps for the three crossings. These figures show the profile of the transmission lines as they will transverse the Preserve. Paralleling the line profile is the maximum vegetation height profile. This is based on maintaining a mini-mum clearance between the trees and the future 230 kV underbuild. Initial vegetation heights, therefore, will provide for a somewhat larger clear-ance to allow for 3-5 years growth.

The areas corresponding to lowest conductor sag and river banks will be principally restored as a shrub community. This will prove beneficial in four ways:

1. A shrub community can help retard trowth of trees in the right-of-way (ROW).

2. Productivity of the R0W may be increased by establishing a shrub community which is attractive to, and functional for, wildlife.

3. Maintenance costs for a shrub community are less over the long term than for a herbaceous community.

4. A shrub community will provide, an effective visual screen at the river's edge.

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Away from the low sag points, the vertical stratification of species r

will be developed to include small trees (23-36 feet) and lower hard-woods (36-82 feet). This vertical diversity will proceed both laterally r

toward the edge of the transmission corridor and axially toward the towers.

i This method of cutting will permit a feathered look as typified in Figure 5.

Since removal of as much as half of a hardwood crown tan place a tree under stress and possible mortality, many of th2 larger hardwoods will have to be fully cut. The removal of these large trees and the topping of others will result in gaps in the canopy and increased light 2

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penetration to the lower strata. Seedings and young trees of the overstory species will be released from a slow growing stage, caused by shading, to a rapid growing stage. Pines, the fastest growing species present, could reach prohibited heights within a few years. Therefore, most young pines will be selectively removed during the initial clearing stage and on a regular maintenance schedule (3-5 years). Young, released hardwoods will also experience increased growth rates, but these will be slower and more Where variable than pines and can be dealt with on an individual basis.

the gaps resulting from large tree removals are not naturally replaced, tree species that do not reach great heights or which grow slowly will be planted. Several of the species listed in Table 1 could be successfully used, while nearly all of those listed in Table 2 could be used with very

' little problems.

Following completion of construction activities, disturbed soils will be improved through aeration by harrowing and discing. This will help restore compacted and churned areas and prepare a seedbed. Cleared areas around the towers and along the access road will be seeded with native herbs and grasses. This will mininize further disturbance of these areas except to selectively remove any sprouting wood plant re-growth.

SITE SPECIFIC DETAILS Line 547 - Neches River Corridor This Preserve crossing area has been already seriously impacted by previous timbering and pipeline construction. Much of the area is already clear cut, particularly the west bank. Therefore, vegetation treatment on this side of the river will be primarily the planting of a

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young seedlings. When restored, this area vill be left in an environ-mental state that is improved over its original condition prior to Gulf States' purchase of the R0W.

Vegetation on the east side of the river is composed of more bay-gall-type vegetation. This vegetation type seldom reaches heights over 40 feet so topping the larger trees should produce a shrub ccmmunity that will be compatible with the power lines and require minimum maintenance.

Riprap at the river banks will be left undisturbed. Except for these riprap areas, the river banks will be planted by a screen of low growing shrubs. These shrubs will be generally chosen from the list provided in Table 2.

Line 531 - Neches River Corridor Like Line 547, this Preserve crossing parallels an existing pipeline R0W. Also like Line 547, clearing for the pipeline flares out near the river on both sides. Therefore, for a significant portion of the affected area, little clearing or topping will be required. These areas will he

. planted with young seedlings after completion of construction. The rest

[ of the crossing area will be treated a described in the general dis-cussion.

e Line 560 - Little Pine Island Bayou Corridor i

Unlike the other two crossings, there is no existing R0W nor exist-I.

ing cleared areas at this crossing. Therefore, the access road and the tower site will have to be cleared and cannot utilize any existing cleared areas as with the other crossings. Extensive selective tree removal will be necessary because of the existing large trees and the lower line clearance for this crossing.

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MITIGATION CRITERIA

SUMMARY

t. Engineering Criteria

1. Tower heights and the number of towers within the Preserve are indicated on Figures 2, 3 and 4.

2. Structure type, conductor sizes and numbers, voltage class and line appurtenances will be specified by Gulf States as the need arises.

3. Access roads to facilities within the Preserve will be routed through naturally cleared areas wherever possible and inside Gulf States' R0W.

4. Minimum line clearances are established by Gulf States' standard practices and by regulatory requirements. Clearance to tree tops are established in accordance with a reasonable maintenance schedule.

Environmental Criteria

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1. A ground survey will be made by Gulf States for each crossing prior to commencement of clearing. Existing plant species will be lo-cated and coded on detailed profile maps, correlating each species with

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topography and noting height of vegetation from ground level. Species in adjacent areas outside the Preserve boundaries that are available for restoration purposes will also be identified.

2. Treatment specifications will be prepared by Gulf States for each crossing. This will include marking trees to be cut, trees to be topped and those to be left undisturbed. These specifications will also indicate which areas should be restored by the planting of young seedlings.

It should be noted that Gulf States does not have responsibility nor the right to initiate restoration practices within the existing pipeline corridors.

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3. R0W preparation will be supervised by Gulf States to ensure that the treatment specifications are not violated.

4. Access roads will be layed out within the ROW in a meandering fashion so as to minimize the visual impact.

5. Treatment specifications will be such that vegetation height increases both laterally and axially away from the conductor sag points.

6. Gaps resulting from removal of large trees will be replaced with native species with lower heights and slower growth rates.

7. Following completion of construction activities, soils dis-turbed within the R0W will be improved through aeration by harrowing and discing.

8. Access roads and tower clearings will be seeded with native herbs and grasses.

9. Throughout the initial clearing and later maintenance of these Preserve crossings, the use of herbicides will not be permitted.

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Table 1. Common east Texas trees with their expected heights at maturity.

Scientific Conmon Height Name Name (ft)

Acer barbatum Florida maple 60 A. rubrum Red maple 100 carya aquatica Water hickory 100

c. cordiformis Bittecnut hickory 100 C. glabra Pignut hickory 120 C. illinoensis Pecan 150

c. laciniosa Shellbark hickory 120

c. leiodermis Swamp hicory 80

c. ovata Shagbark hickory 100 celtis laevigata Sugar hackberry 100 Fagus grandifolia American beech 120 Fraxinus caroliniana Carolina ash 40 F. pennsylvanica Green ash 70 Gleditsin aquatica Water locust 60 1

, c. triacanthos Honey locust' 100 f Liquidambar styraciflua Sweetgum 150 Magnolia grandiflora Southern magnolia 120 Nyssa aquatica Water gum 100 N. sylvatica Blackgum 100

_ Pinus taeda 1.oblolly pine 150 Platanus occidentalis Sycamore 170 Quercus falcata Southern red oak 80 f

i Table 1. (cont'd)

Scientific Comon Height Name Name (ft)

Q. laurif olia Laurel oak 100 Q. lyrata Overcup oak 100 Q. nigra Water oak 80 Q. phelios Willow oak 130 Q. prinus Chestnut oak 100 Q. shumardii Shumard oak 120 Salix nigra Gulf black willow 125 Taxodium distichum Bald cypress 130 Ulmus americana American elm 120

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Table 2. Common east Texas shrubs and small trees with their expected

- heights at maturity.

Scientific Common Height Name Name (ft)

Alnus serrulata Hazel alder 20 Aralia spinosa Devil's walkingstici 35 Asimina parviflora Dwarf pawpaw 12 A. triloba Comon pawpaw 40 Betula nigra River birch 50 Carpinus caroliniana American hornbeam 35 Cephalanthus occidentalis Comon buttonbush 18 Chionathus virginicus Fringe-tree 35 Cornus drummondii Roughleaf dogwood 30 C. florida Flowering dogwood 15 C. fo er.ina Stiff dogwood 15 Crataegus sp. Hawthorns 25 Cyrilla racemiflora Sw mp cyrilla 30 Diospyros virginiana Comon persimon 40 Econymus atropurpureus Brook euonymus 25 Forestiera acuminata Texas forestiera 30 F. angustifolia Narrow-leaf forestiera 25 Halecia diptera Two-wing silverbell 30 Ilex coriacea Large gallberry 15 I. decidua Possum-haw holly 30 2'

1. glabra Inkberry 12 .-

I. opaca Americar holly 70

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Scientific Common Height Name Name (ft)

I. vomitoria Yaupon 25 Lindera benzoin Common spicebush 20 Magnolia virginiana Sweetbay 30 Morus rubra Red mulberry 70 Myrica cerifera Wax myrtle 10 Ostrya virginiana Eastern Hophornbeam 60 var. Lasia Persea barbonia Redbay 70 Planera aquatica Water elm 40 Prunus angustifolia Chicksaw plum 25 P. mexicana Mexican plum 25 Sabal minor Dwarf palmetto 8 Sambucus canadensis American elder 30 Sassafras albidum Sassafras 90 Sophora affinis Texas sophora 25 Styrax americanum American snowbell 9 Symplocos tinctoria Sweetleaf 40

, Tilia as:aricana American basswood 50 T. caroliniana Carolina basswood 50 g Toxicoderdron vernix Poisan sumac 25 Ulmus alata Winged elm 60 U. crassifolia Cedar elm 90 1

Viburnum acerifolium Mapleleaf viburnum 6

Table 2. (cont'd)

Scientific Conmon Height Name ,,

Name (ft)

v. dentatum Arrow-wood viburnum 15

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