01-03 shin-hannou(japan).doc

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IEA Hydropower Implementing Agreement Annex VIIIHydropower Good Practices: Environmental Mitigation Measures and Beneftsase study !"#!$: Biological %iversity # &'in#Hannou &u(station) *apan

Key Issue:1-Biological Diversity10- Landscape and Cultural Heritage

Climate Zone:Cf: Temperate Humid Climate

Subjects:- Slope Afforestation and Revegetation in Harmony wit Surrounding !nvironment

Effects:- !arly restoration of landscape and ecosystem in developed areas

Project Name: S in- Hannou Su"stationCountry: Saitama #refecture$ %apan &Asia'

Implementing Party & Period - Project: To(yo !lectric #ower Co)$ *nc) &T!#C+'

1,, &Commencement of construction' -- ood Practice: To(yo !lectric #ower Co)$ *nc) &T!#C+'

1,, -

Key !ords:

.iodiversity$ Revegetation /et ods$ #eople-friendly orests

"bstract:*n t e construction wor( of t e S in-Hannou Su"station$ t e idea of "iotope was

incorporated in t e design stage and a variety of environmental measures were ta(en witt e aim at its coe istence wit nature) #articular attention was paid to t e restoration of ecosystem at low costs t roug t e application of t e power of nature) or e ample$ for t e

afforestation of slopes and t e development of forests$ plants were raised from seeds to uset eir in erent power to vegetate) .esides$ watersides spaces in w ic wild animals andplants were a"ita"le were created) T e met ods and t e ideas adopted in t is pro2ect areapplica"le not 2ust to t e construction wor( of su"stations "ut also e tensively to large-scalepro2ects including ydropower development)

1. Outline of the ProjectThe Shin-Hannou Substation construction work is to build a 500 kV substation in Saitama Prefecture,in the site shown in Fig.- , to meet the demand for electricit! in the southwest area of the "refectureand the northwest area of Tok!o ad#oining it and to strength the bulk "ower s!stem. S"ecifications of the substation are shown in Table- .



Table- S"ecifications of the Shin-Hannou Substation $utline of facilities

Facilities This Stage Final Stage

%ain Transformer 500&'(5kV, ,500%V)

*with a built-in + T

' banks banks

/us 500kV nit bus 1ouble bus with bus-ties

'(5kV Single bus with

bus-tie

- ditto -

Transmission lineterminal

500kV *o2erhead ' circuits 3 circuits

'(5kV *o2erhead ' circuits 3 circuits

otar! 4ondenser )d2anced "hase 4a"acit! '00%Var +agging "hase ca"acit! (0%Var

unit unit

Total )rea (. ha )ccess oad +ength6 a""ro7. '. km, 8idth6 3 m, %a7. 9radient6 ' :

Site )rea . ha ;le2ation <30 m abo2e sea le2el

2. Features of the Project AreaThe construction site of the Shin-Hannou Substation is within the Prefectural $kumusashi =aturalPark located in a "lace between hills in Hannou 4it!, which "ublici>es itself as a ?town of green andlim"id streams.@ The site is in an urbani>ation control area. The areas around the site are abundant

with ri2ers and natural forests but it takes onl! an hour or so b! train from a downtown of Tok!o. )s itis located so con2enientl!, "eo"le make a com"an! of nature on holida!s b! fishing or bathing in a

ri2er and mountain walking. $n the other hand, the construction of new towns and estate de2elo"mentfor golf courses are under wa! now. Such a situation aroused en2ironmental consciousness of both theadministration and the inhabitants and as much endea2or as "ossible to maintain harmon! with theen2ironment of surrounding areas was demanded in the construction of the substation.

'

Saitama Pref.

Shin-Hannou Sub.

Fig.- %a" of the location



3. Major I !actsStarting an en2ironment im"act assessment in AA , the Tok!o ;lectric Power 4o., Bnc. "re"ared are"ort on its in2estigations of en2ironment im"act u"on com"letion of the construction work in )"rilAA . Such in2estigations are still continuing.The local autonomous bod! *Saitama-ken sti"ulated ?the $rdinance for Protecting 9reen in Saitama,$ur Homeland,@ setting a goal of increasing afforested areas in it to 3,300 ha b! '005. $n the basis of the ordinance, de2elo"ers in the "refecture are reCuired to sign ?the 9reen )greement@ and to

maintain a certain afforestation rate *'& 0 minimum of the area of a construction site *or, in the case of e7tension work, of the area of the e7tended s"ace . For the construction of this substation, thede2elo"ment was attached with conditions that an afforestation rate of '0: should be secured and that "lanted trees should be at least 0 cm in height on an a2erage at the com"letion of the work.)ccordingl!, in this construction work, to erase traces of construction work as much as "ossible in theareas to be de2elo"ed and to restore the ecos!stem, which had been reared b! the forests of the$kumusashi region, were ma#or en2ironmental "roblems.

". Mitigation MeasuresBn the en2ironmental "lanning in this "ro#ect, em"hasis was "laced on the use of an afforestationmethod that would allow the abo2ementioned "roblems to be sol2ed, and on the selection of "lantsthat would work as the most effecti2e means for earl! restoration of the ecos!stem. S"ecial attention

was "aid to the following61esigning slo"e afforestation works that could minimi>e concrete structureD

' 1esigning a regulating reser2oir and a waterwa! in consideration of the ecos!stemD and< ;arl! restoration of a landsca"e and an ecos!stem in harmon! with the en2ironment of

surrounding areas.4oncrete measures as shown below were taken to attain the ob#ects to < . For e7amining and takingthese measures, local administrati2e officesE and inhabitantsE understanding was sought and their acknowledgement was obtained.

Slo"e afforestation works was designed so as to minimi>e concrete structures.a =ature-like cut retaining walls b! the geofiber method

* sing the geofiber method for cut "ortions achie2ed the "lanned afforestation without makingconcrete block retaining walls for slo"e "rotection.

b =ature-like retaining walls of embankment b! the geogrid reinforced earth method

* sing the geogrid reinforced earth method ser2ed to do awa! with concrete retaining wallsand at the same time to reduce the area of de2elo"ment in achie2ing the "lanned slo"e

afforestation.c Such manurial "lants as bush clo2er and maackia were mainl! selected in designing slo"e

afforestation.*The shotcrete works with the base concrete mainl! containing seeds of manurial "lants ser2edto do awa! with slo"e landslide "re2ention works and to achie2e the ob#ecti2e of slo"e "rotection b! afforestation.

' ) regulating reser2oir and a waterwa! were designed in consideration of the ecos!stem.*So that a regulating reser2oir and a waterwa! could "ro2ide water amenit! s"aces for smallanimals and aCuatic life, concrete structures were reduced to a minimum necessit! and a nature-like waterwa! was created b! arranging nati2e rocks.

<



< ;arl! restoration of a landsca"e and an ecos!stem in harmon! with the en2ironment of surrounding areas

*1irectl! seeding nati2e s"ecies of deciduous broadleaf trees and e2ergreens im"ro2ed groundconser2ation and materiali>ed earl! re2egetation.

Of the above measures, particularly unique ones are detailed in the following.

4.1 Design of slope afforestation mainly with such manurial plants as bush clover and maackiaBn the "rocess of building a substation, large slo"es are "roduced as a result of road and landde2elo"ment works. 8hen such slo"es and bare land are "roduced as de2elo"ment work "rogresses,

"rom"t restoration to their original states is reCuired not onl! from the 2iew"oint of a""earance or landsca"ing.

Table-' 9ermination and growth characteristics of herbaceous "lants and wood! "lants

1i2ision

Btem

Bntroduced Herbaceous Plants 8ood! Plants

9ermination

characteristics

conditions

9ermination

rate

Ver! good * 0-A0: =ot good *'0-30:

9ermination

tendenc!

Time6 -' weeks Time6 ) few month-ne7t !ear

9ermination

bed

Thick bed not necessar! *surface

seeding

Should be free from erosion for '-<

weeks

Thick bed necessar! *Seeds to be

buried in the ground

Should be free from erosion for long

time *) few month-ne7t !ear

4limate Tem"erate and humid *for short

"eriod of time

Tem"erate and humid *for long time

9rowth

characteristics

conditions

9eolog! Soil height6

Sand! soil G'5mm

4ohesi2e soil G'<mm

Soil height6

Sand! soil G'5mm

4ohesi2e soil G'5mm

9radient 5 or gentler 9entle slo"e of 30

Fertili>er

eCuirement

+arge Small *manurial trees

4limate To grow in tem"erate and humid

en2ironment

To grow in tem"erate and humid

en2ironment

S"eed of

growth

Fast Slow

Height of

grass or tree

+ow High

Simultaneousl!9erminationtendenc!

9erminationtendenc!

Slowl!



1e"th of root Shallow 1ee" *9rass roots elongate relati2el!

dee".

State of

growth

To grow in crowds easil! *To wither

all together when the! grow thick.

To be scattered graduall! *Bn case of

large number of 2aried s"ecies,

"ressure e7erts.For such slo"es and blighted areas, in association with construction work, co2ering with e7oticherbage or "re2ention works using herbage in combination with grating crib works ha2e been ado"tedso far in most cases. )s shown in Table-', whereas e7otic herbs are e7cellent in germination andCuickl! grow in gregariousl!, the! are known to ha2e control and maintenance "roblems freCuentl!degenerate in two or three !ears after the com"letion of work because of their high reCuirements for fertili>er.$n the other hand, wood! "lants *manurial "lants e7tend their roots dee" into the ground once the!start growing and form a root s!stem la!er although their rate of initial germination is low and so the!can increase the stabilit! of slo"es. The "roblem in using wood! "lants is how to "re2ent erosionduring the "eriod "receding their germination.Such being the case, ?the higher-mode aggregated shotcrete works@ was chosen for the "ro#ect. This isthe method to "neumaticall! con2e! higher-mode aggregated soil ha2ing features similar to forest soilonto slo"es b! means of a "um". *The aggregated soil is highl! air- and water-"ermeable, "orous soilin an ad2anced state of decom"osition. This is an e7cellent method that not onl! creates highl!nutriti2e soil la!ers but also "re2ents erosion of the surface la!er of a slo"e.

$ne of the most im"ortant matters in restoring a slo"e on which 2iolence is done b! de2elo"ment is toset ?a target communit!@ b! looking far into the future. Bn the "resent case, a communit! ha2ing thefollowing functions was targeted. Further, so as to do awa! with as man! concrete structures as

"ossible, "articular attention was "aid to "rotection and afforestation of cut slo"es and slo"es of embankment "roduced as a result of clearing a hill! landform.

The function to ada"t to infertile land and dr! land, be ca"able of germinating and growing on astee" slo"e and ha2e soil im"ro2ing abilit!D

' The function to bind soil tightl!, e7tend the root s!stem dee" into a slo"e and retain weatheredsoil la!ersD and

< The function to grow Cuickl!, integrate in trees and shrubs in surrounding areas and efface tracesof de2elo"ment.)s a result of searching "lants that could fulfill the abo2e functions and carr!ing out field tests, a blend of bush clo2ers, maackias, indigo "lants and sericeas was found to attain the best balance*Table-< . These manurial "lants function to fi7 s!mbiotic free nitrogen and im"ro2e soil.

Table-< /lend of seeds

Plant name ate of

germination

;ffecti2e

number

of

grains&g

)ntici"ate

d number

of "lants&

m '

Seeding Cuantit! *g&m <

S"ra!

thickness6 'cm

*standard

thickness

S"ra!

thickness6

<cm

S"ra!

thickness6

<cm-5cm

5



+ow

trees

/ush clo2er

%aackia

Bndigo "lant

50:

0:

50:

3

<

'0

,000

50

50

'A. '

.A<

'.50

. <

(. 0

<.(5

'A. '

.A<

'.50 =ati2

e

Sericea 50: A 500 '.0' <.0< '.0'

The total area of afforestatin using wood! "lants is . ha.

4.2 Design of regulating reservoir and waterway in consideration of the ecosystem=ature-like waterwa! made in u""er stream

of regulating reser2oir Bn consideration of the local to"ogra"h!,

geolog! and stream regime, the waterwa!connected to the regulating reser2oir with theca"acit! of ,000 m < was built as a nature-like bioto"e waterwa! defined b! randoml! "laced nati2e without using concrete. )s aresult, nature has been restored and water amenit! s"aces ha2e been created *Fig.-< . Bnthis "rocess, a great deal of effort went to thecreation of as man! "orous s"aces as "ossible

for "ro2iding small animals with habitats andthe formation of meanders for the waterwa!.

' 1esign of waterwa! in consideration of li2ingthings

For the waterwa!, an animal-friendl!configuration was ado"tedD in "ortions of thewaterwa! of which three sides were made of

concrete since a nature-like form could not beretained due to limitations in s"ace of the site,

the bottom of the waterwa! was co2ered withearth, sand and gra2els and slo"ed ste"s were "ro2ided for animalsE access to the water.

3

Fig.-< =ature-like waterwa!

Fig.-' Slo"e afforestation using mainl! manurial trees*Photo shows the geofiber method I afforestation



4. Design of early revegetation by direct seedingTo secure the afforestation rate for this substation, limitation in the area of de2elo"ed land made itine2itable to "lant trees on the slo"es of embankment. =e2ertheless, the slo"es of embankment of thesubstation reCuired not onl! the fulfillment of the afforestation rate b! tree "lanting in harmon! with

the en2ironment of surrounding areas but also the Cualit! that could concurrentl! "la! the role of slo"e "rotection works from the stand"oint of disaster "re2ention. Therefore, an afforestation design

was made on the basis of a sur2e! of 2egetation in search of a method for restoring nature inre2egetated forests, for which "otential natural 2egetation of surrounding areas was taken intoaccount.

Table- Potential natural 2egetation based on sur2e!Potential

natural

2egetation

Form of colon! Potential location 4orres"onding e7isting 2egetation

Fir&Ja"anesestar anise

communit!

%i7edconiferous and

broad-lea2edforest in which

fir and oak trees

From ridge to middle ofslo"e where dr!, brown

forest soil and slightl! dr!, brown forest soil are

distributed

- Fir&Kuercus glauca communit!

- Kuercus&Ja"anese chestnut tree

communit!

- )ralia elata& ubus hirsutus

communit!

Lelko2atree&

Ja"anese

ma"le

communit!

/road-lea2edforest in which

>elko2a trees

and oak trees

grow mi7edl!D

e2er- reens

/ottom of ra2ine andlower "ortion of slo"e

where dr!, brown forest

soil and a""ro"riatel! wet

brown forest soil are

distributed.

- Ja"anese cedar& hinoki c!"ress "lantation

- 1is"orum sessile grou".

- )cer "lamatum& ubus hirsutus

communit! and others

For the e7ecution method of affrestation with these nati2e "lant s"ecies taken into consideration,direct sowing b! means of seeding works *from seeds to germination and growth was chosen to

balance the abo2e-the-ground "ortion *trunk, branches and lea2es and the subterranean "ortion of the "lant. )s the method of construction, the higher-mode aggregated shotcrete method was em"lo!ed asmentioned earlier.The area of re2egetation b! direct seeding is <.' ha.

#. $esults of the Mitigation MeasuresTo assess the im"act of the construction work on surrounding en2ironment, en2ironmental im"actsur2e! s ha2e been continuousl! carried out since AA . )lthough it was feared that the intended rateof afforestation could be reached at the com"letion of the substation b! re2egetation through directseeding instead of the con2entional method of tree "lanting, deciduous trees grew satisfactoril! as

(



Fig.- Present state of afforested area **the "hoto on the right shows a Kuercus

shown in Fig.- and 5 and it was assured that the target *an a2erage height of trees at the time of com"letion6 0 cm sti"ulated b! ?the 9reen )greement@ with Saitama-ken could be achie2ed *Fig.-3 .



Fig.-5 Present state of afforested area *'

42

120 120140

55

135150

220

68

150

180

300

0

50

100

150

200

250

300

350

0 1 2 3 4 5

c m

Min AveMax

!"#$%&'( ) *+, 180cm

(4om"letion !ear

Standard 2alue set forth b! ?9reen )greement 6)2erage height of trees at the time of com"letion M 0 cm H

e i g h t o

f t r e e * c m -

The number of !ears after com"letion *!ear

Fig.-3 4hanges in the height of deciduous tree

%. $easons for &uccessPrior to the start of the construction work, s"ecialists including members of the Ja"anese Societ! of 9reening ;ngineering were in2ited to form the ?;arl! e2egetation Stud! Team@ and the constructionwork was carried out while e7amining "ro"osed measures for en2ironment "rotection and their effect.This is belie2ed to be a ma#or reason for a generall! satisfactor! result of the en2ironmental "rotectionmeasures.

'. Outsi(e )o ents=ikkei 4onstruction, =o2ember AA(

ated the "ro#ect high as a good e7am"le of ?"re2enting nature from being lost b!de2elo"ment.@

' %aga>ine ?Sun,@ 1ecember AA3Taking u" ?The Shin-Hannou Substation@ as an attem"t for s!mbiosis with nature, featured?the bioto"e techniCue@ and ?slo"e "rotection b! making use of su""orting force of roots of "lants.@

A



*. Further Infor ation!.1 "eferences

Saito, Noshi#i6 ?;n2ironment "rotection measures in the Shin-Hannou Substation,@ 1enr!oku1oboku, AA(

' Namadera, Noshinari *Shinshu ni2ersit! 6 ?9reen design for regeneration of naturalen2ironment,@ AA

< Namadera, Noshinari *Shinshu ni2ersit! 6 ?Planning and designing of slo"e afforestation,@ AA%i!awaki, )kira *=ational ni2ersit! of Nokohama 6 ?Potential natural 2egetation of the

%etro"olitan area,@ A(3

!.2 #nquiries4onstruction 1e"artment

Tok!o ;lectric Power 4o., Bnc. *T;P4$Tel6 I -<- ' 3-

Fa76 I -<- ' 3- '3Ae-mail6 htt"6&&www.te"co.co.#"

0

=ew ;nerg! Foundation, Ja"an, '003

http://www.tepco.co.jp/





This case history of hydropower good practice is published for educational and informational purposes only and

may not be used for any other purpose. Duplication for commercial purposes is prohibited. The author(s) of this

publication make no express or implied warranties concerning this case history, including no warranty of

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01-03 shin-hannou(japan).doc

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