ML20063D811
| ML20063D811 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 02/07/1980 |
| From: | BECHTEL GROUP, INC. |
| To: | |
| Shared Package | |
| ML20063D800 | List: |
| References | |
| PROC-800207, NUDOCS 8207130142 | |
| Download: ML20063D811 (33) | |
Text
.
d D -
f EROSION AND SEDIMENTATION CONTROL PLAN FOR THE LIMERICK GENERATING STATION UNITS 1 AND 2 PHILADELPHIA ELECTRIC COMPANY Bechtel Power Corporation San Francisco, California Revised for Imp 5anentatib g 7 37 Reiss b t/M/N Revised and Reissued for ImplmentatiF d b b 4/2.3/71 Ibvised and Reissued for Inplsentaticn )pR 4e> h k f2//4/73 Issued For Implementation M Afot NO. DATE REVISIONS APPROVALS 8207130'42 1 820709 PDR ADOCK 05000352 A PDR
I e i se owere b evectii Lt.Ttst l Laftst LCTEst LaTesf LATEST d "MtY SMEET M ET .g y. entti ,gy setti ,gy
, ' " 1? l ,ig, {r.ET ' ,gy .g y, gg y.
y il3 l C-1 2 _
ul 1 C-2 2 ,
2
- iii t>.1 1 iv 3 D-2 1 1 1 E-1 0
,2 1 F-1 3 3 2 F-2 3 4 1 5 2 6 2 7 3 8 2 9 3 10 2.
11 2 12 3 13 1 1
_14
_A .1 1
_B-1 0
_B-2 1 B-3 1 B-4 1 B-5 1 B-6 0 3 FM0 Revised & Reissued rnr Tr 31,mnmi nn 447 b i
NM i i g ssyng g g g, kvise'd and Reissued g '
hyg 1 ND+ f geat=hm 0
'# 73 '
men 95Hm M he b to. DATE ntvissoNs BY CH(D APP'D No. Daft A t V 111 D N s 8Y CHCD APP'O FACING SHEET LIMERICK GENERATING STATION, UNITS 1 & 2 JOB No 8031 PHILADELPHIA ELECTRIC COMPANY EROSION AND SEDIMENTATION CONTROL Posen Ano PLAN .
3 i s.ou s i n i a Sheet 1 otvision
l 1
6 s -
TABLE OF CONTENTS O
CONTROL PLAN 1.0 SCOPE AND RESPONSIBILITY
2.0 REFERENCES
2.1 Handbooks 2.2 Bechtel Drawings and Specifications 3.0 STAGING AND AREAL' EXTENT OF EARTHMOVING 3.1 Earthmoving before January 1, 1974 3.2 Earthmoving after January ', 1974 4.0 CONTROL MEASURES AND FACILITIES DURING CONSTRUCTION-4.1 Earthmoving before January 1, 1974 4.1.1 General Requirements 4.1.2 Powerblock Area 4.1.3 Cooling Tower Area -%
4.1.4 Construction Laydown Areas 4.2 Earthmoving after January 1, 1974 4.2.1 General Requirements 4.2.2 Spray Pond Area 4.2.3 Schuylkill River Facilities 4.2.4 Cooling Towers and Miscellaneous Earthwork 4.2.5 220 kV'and 500 kV Switchyards
~
]
ii Rev. 1
o
- i 4.3 Long-term Maintenance Program 4.3.1 General Requirements 4.3.2 Control of Traffic and Construction Activities 4.3.3 Holding Ponds and Debris Basins 4.3.4 Maintenance Review 5.0 PERMANENT CONTROL MEASURES AND FACILITIES 5.1 General Requirements 5.2 Finished Grading and Drainage Control - Power Plant Facilities 5.3 Finished Grading and Drainage Control - Switchyards 5.4 Permanent Seeding and Landscaping APPENDICES APPENDIX A Deleted APPENDIX B Conditions of Disturbed Areas during November, 1973 B.1 General B.2 Powerblock Area B.2.1 Holding Pond (Under Construction)
B.2.2 Underground Storm Drainage System I
B.2.3 Surface Conditions B.3 220 KV Switchyard L.4 Cooling Tower Area B.5 Construction Laydown Areas iii Rev. 2 i
o APPENDICES APPENDIX C Design Criteria-Holding Ponds and Debris Basins C.1 General C.2 Holding Pond for Powerblock Area C.3 Ddaris Bakin for Cooling Tower and Spray Pond Areas APPENDIX D General Practices and Design Criteria-Permanent Drainage D.1 General D.2 Finished Grading D.3 Storm Runoff Design Criteria D.4 Drainage Ditches and Interceptor Ditches D.5 Outlets for Storm Runoff Discharges APPENDIX E Reference Drawings for Information APPENDIX F
/ h Master Erosion and Water Polution Control Plans iv Rev. 3
i
\
1.0 SCOPE AND RESPONSIBILITY )
Thi" Control Plan applies to the Limerick Generating Station, Units 1 and 2, owned by Philadelphia Electric Company. This control Plan has been developed to be in conformance with Chapter 102. Erosion Control which was added to the Rules and Regulations of the Pennsylvania Department of Environmental Resources on September 21, 1972. This Control Plan provides the requirements and layout needed in order to implement and maintain the measures and facilities used to control accelerated erosion and the resulting sedimentation.
Also, Appendices have been included to provide informa-tion regarding the site conditions and the general practices and design criteria used to develop the control measures and facilities.
As the agent of Philadelphia Electric Company, this written Control Plan was initially developed in November,1973 by Bechtel Power Corporation (Bechtel)
Engineer / Constructor for the Limerick Generating Station.
Control measures implemented and maintained at the Limerick site prior to the issuance . of this Control Plan were under the direct guidance and supervision of Bechtel Field personnel. Bechtel is responsible for the development and implementation of this Control Plan for the following:
u) Corrective measures and facilities for areas disturbed before January 1, 1974 involving the Powerblock Area, Cooling Tower Area, and
~"
Construction Laydown areas.
(2) Measures and facilities for earthmoving activities after January 1, 1974 involving the Spray Pond Area, Schuylkill River Facilities, Cooling Tower Area, and miscellaneous earthwork.
(3 ) Long-term maintenance throughout the period of construction activities for the power plant facilities.
(4 ) Finished grading and permanent drainage control for the power plant facilities.
Parties other than Bechtel are responsible for the develop-ment and implementation of thLs Control Plan for the following:
(1) Measures and facilities for earthmoving activities after January 1, 1974 involving the 500 kV Switchyard and the 220 kV Switchyard.
Rev. 1 j
(2) Finished grading and permanent drainage control for the switchyards.
(3 ) Permanent seeding and landscaping for the entire project.
Separate control plans will be developed for the Perkiomen Makeup Water System which is part of the Limerick Generating Station, but is remote from the main site. These control plans will be developed prior to the start of earthmoving. The Perkiomen Makeup Water System consists of:
(1) Perkiomen Creek Pumping Station and related facilities located at Perkiomen Creek. ,
(2) Perkiomen Makeup Water Pipeline (apprcximately 8 : miles long) from the Perkiomen Creek Pumping Station to the Limerick site. -
2.0 REFERENCES
2.1 Handbooks The following reference handbooks shall be used in conjunction with this Control Plan for the implemen-tation of the required control measures and facilities:
(1) Erosion and Sediment Control Handbook; Montgomery County Soil and Water Conservation District; June, 1970; hereinafter referred to as the Montgomery County Handbook.
(2) Guidelines for Erosion and Sediment Control Planning and Implementation; U.S. Environmental Protection Agency; EPA-R2-72-015; August, 1972; hereinafter referred to as the EPA Guidelines.
Additional references, other than the above listed, may be used in conjunction with this Control Plan in order to implement and maintain the required control measures and facilities.
In some instances, this Control Plan requires control measures and facilities to be implemented and main-tained, but does not provide the specific details.
For these cases, as the need ar'ises, the cognizant Field Engineer shall choose the type or method of control by referring to any of the above references.
If the measure chosen does not effectively control the problem, the problem shall be forwarded to the Project Engineer for resolution.
Rev. 1
2.2 Bechtel Drawings and Specifications Tne latest revision of the following drawings and specifi-cations shall be used in conjunction with dd3 Control Plan for the implementation of the required control measures and facilities:
Drawing 8031-C Storm Drainage - Plant Area Drawing 8031-C Drainage - Tower Area Drawing 8031-C Drainage Details - Tower Area Drawing 8031-C Misc. Yard Details Drawing 8031-C Plan 0 Area Roads Drawing 8031-C Service Roads-Plan & Profile Drawing 8031-C Plant Parking i
Drawing 8031-C Access Road - Plan and Profile Drawing 8031-C Road Sections and Details Drawing 8031-C Yard Area Drawings thru 8031-C-69 Drawing 8031-C-880 - Holding Pond - Plans and Sections Drawing Z-101-60.0 - Holding Pond Water Treatment Drawing SK-C-391 - Control Measures and Existing Conditions-North Areas i
Drawing SK-C-392 - Control Measures and Ekisting Conditions-South Areas Drawing SK-C-393 -
Control Measures and Existing Conditions-East Areas Drawing SK-C-394 -
Debris Basin for Cooling Tower and Spray Pond Areas
- . . - . - ... .. ........'...- n. . .
Drawing SK-C-395 -
Earthmoving and Control Measures -
500 KV_ Switchyard Area
. - - ~ . . . . ,~ - .
Specification 8031-C Site Preparation and Earthwork Spray Pond Drawings and Specs.-Nos. and titles later i
Rev. 2
Additional Bechtel drawings and specifications, other than the above listed, may be used in conjunction with this Control Plan, in order to implement and maintain the required con-
. trcl mcacurcs and facilities.
3.0 STAGING AND AREAL EXTENT OF EARTHMOVING 3.1 Earthmoving before January 1, 1974 For the location and topography of the Limerick site refer to Drawing 8031-C-1. For the natural site and soil conditions refer to Section 2 of the Preliminary Safety Analysis Report.
Earthmoving was started at the Limerick site in July, 1970 and was suspended in December, 1971.
During that period nearly all of the required earthmoving at the site was completed. Areas were cleared and graded for permanent facilities in-cluding the Powerblock Area, 220 kV Switchyard, Cooling Tower Area, and access roads. The below grade excavation has been completed for the Power-block and for most of the other facilities in the Powerblock Area. Also, due to the large volume of construction materials and equipment to be received at the site, storage and laydown areas were cleared and graded. Efforts were made to keep the areal extent of earthmoving to a minimum. Some minor earthmoving activities continued from December, 1971 until February, 1972 consisting only of construction of drainage ditches, culverts, etc. -%
Construction activities resumed in July , 197 3. No major earthmoving was undertaken between then and January 1, 1974. The only activities during this period involving earthmoving consisted of cleanup in the excavated holes of the Powerblock Area, furtherance of construction of the holding pond for the Powerblock Area, furtherance of construction of the Site Access Road over Possum Hollow Run, and providing more parking areas. None of these consisted of a significant amount of clearing topsoil or of earth cuts and fills.
For the conditions and areal. extent of the dis-turbed areas during November,1973, refer to Appendix B. Appendix B also outlines some of the control mea-sures and facilities already implemented at the site.
Rev. 1
. '3.2 Er.rthmoving after January 1, 1974
, Construction activities at the Limerick site are scr eduled to be completed by 1982. A very small per-ce stage of these activities will involve earthmoving.
Earthmoving activities after January 1, 1974, at the Limerick site covered unBer this Control Plan are as follows :
Start of Earth-Activity Areal Extent .(acres) , moving Forecast Date Spray Pond 18 ,,
January,'1978 Schuylkill River Facilities 7 March, 1978 Cooling Tower Area- 5 January, 1977 Miscellaneous Earthwork Negligible -
Intermittent 500 kV Switchyard 23 (Later) 220 kV Switchyard 4 (Later)
Each of these earthmoving activities is less than 25-acres and is located in an entirely different locat-ion from the others. Also, each of these earthmoving activities is scheduled independently of the others.
For location of these permanent facilities requiring earthmoving after January 1, 1974 refer to Drawing 8031-C-1.
Earthmoving for the Spray Pond is within the existing laydown areas and will consist of excavation for~the pond and grading the surrounding area. Earthmoving for the Schuylkill River Facilities will consist of stripping and clearing areas for construction, exca-vation for the pumping station at the river, excavation for underground piping, excavation for the diffuser at the river, and fills for the service roads.
Earthmoving for the cooling Tower Area will consist of removal and compaction of existing fills and of excavation and backfill for foundation structures.
Miscellaneous earthwork which consists of pipe trenches, roadways, miscellaneous excavations, finish grading, etc., is located within the limits of past grading, is negligible in areal extent, and will occur intermittently throughout most of the period of construction. Earthmoving for the 500 kV Switchyard will consist of clearing and grading for installation of switchyard equipment, plus excavating and transporting fill material from borrow pit as shown on '
Drawing SK-C-395. Earthmoving for the 220'kV Switchyard will consist of grading for installation of switchyard equipment.
Rev. 2 i
An encruachment permit application hos basn filed with the U.S. Corps of Engineers for the future construction adjacent to the Schuylkill River.
4.0 CONTROL MEASURES AND FACILITIES DURING CONSTRUCTION Refer to Drawings SK-C-391, SK-C-392, and SK-C-393 for overall layout of the required control measures and facilities to be used during the period of construction.
4.1 Earthmoving before January 1, 1974 4.1.1 General Requirements Sections 4.1.2, 4.1.3 and 4.1.4 define the control measures and facilities that shall be implemented for those areas that were dis-turbed by earthmoving before January 1, 1974.
The required control measures and facilities which have not already been implemented shall be implemented at the earliest possible date.
4.1.2 Powerblock Area The butterfly valve at Catch Basin No. S-5.3 shall be in a closed position at all times to direct water to the holding pond for treatment except during rainstorms. During rainstorms the valve shall be opened after the first 20 minutes of the storm. If water is not being pumped and/or discharged into the storm drainage system, the valve shall be left in an open position since holding pond discharge criteria do not apply to storm water run-off. For details of the diversion facilities refer to Drawing 8031-C-13 and 8031-C-20. For details of the holding pond see Drawing 8031-C-880.
Water from all excavated holes in the Powerblock Area, including the Circulation Water Pump Structure, shall be pumped and/or discharged to the holding pond except as mentioned below. Discharges may be conducted to the underground storm drainage system only when the valve at Catch Basin No. S-5.3 is closed to direct the flow to the holding pond, or when the discharge water has been tested for compliance with holding pond discharge critiera. Tests shall performed by the Pollution Control Engineer or qualified client personnel. If the water in an excavation meets all holding pond discharge criteria, it may be pumped and/or discharged into the storm drainage system regardless of the position of the valve at Catch Basin No. S-5.3. The pump shall be situated so that the sediment from the bottom of excavations is not discharged to the storm system.
Rev. 2 r . . . . .-
An doccribed in the diccharge permit application filed with the U.S. Environmental Protection
- Agency, the subject holding pond has a two-fold purpose of sampling and treating discharges during dewatering of excavations and also dis-W during preoperational testing of permanent
' _ Plant facilitie,s within_the_Powerblock Area.
, . To be in compliance with the permit application, all of these preoperational discharges shall be routed to the holding pond except as stated below.
The holding pond shall be operated and maintained in accord ance with Drawing Z-101-60.0 Per Drawing Z-101-60.0 the holding pond is operated on a batch decant basis to allow sampling and treating.
Whenever samples do not meet the specified water quality limits, the decanted water is treated and recirculated to the pond.- An overflow pipe is also provided for emergency overflow conditions.
For the capacity of the pond regarding erosion
,nd a sedimentation control see Appendix C.
Permanent (or temporary substitutes) downhill drain pipes (with baffled outlets and riprep) -4 located on the fill slopes of the Powerblock Area shall be installed for use during the period of construction. Those drains (or tneir substitutes) to be installed are.shown on Drawing SK-C-392. The existing downhill drain (discussed in Section B.5 of Appendix B and shown on Drawing Sk-C-393) shall be continued underground to a baffled outlet and j
riprap adjacent to Possum Hollow Run, if conditions develop warranting further action.
Rev. 3
4.1.3 Cooling Tower Area Measures shall be made to divert any surface runoff from going down the slopes toward the Circulating Water Pump Structure, to the Powerblock Area, or to the service roads below. A debris basin has been constructed to receive flows from the Cooling Tower Area.
Surface runoff and pumped discharges from the Cooling Tower Area shall be directed to the debris basin or Power block Storm Drain System.
The debris basin has been constructed in accor-dance with the details and notes of Drawing SK-C-394 and maintained in accordance with Section 4.3.3.
4.1.4 Construction Laydown Areas Control measures have already been implemented for the previously eroded strip (as shown on Drawing SK-C-391) along the Plant Access Road and the Sanatoga Road. However, this strip shall be monitored and maintained in accordance with Sec-tions 4. 3.1 and 4. 3.4 of this Control Plan.
The fill slopes of the stripped and filled area at the northwest corner of the site shall be seeded or covered with dumped rock.
4.2 Earthmoving after Jandary 1, 1974 4.2.1 General Requirements Sections 4.2.2, 4.2.3,4.2.4 and 4.2.5 define
- the control measures and facilities that shall I be implemented and maintained for the areas covered under this Control Plan that will be disturbed after January 1, 1974, by earthmoving activities.
With regard to earthmoving and other construction activities by Bechtel subcontractors on the site, the cognizant Bechtel Field Subcontract Engineer-shall check the actions of the subcontractors to determine that the requir.ed control measures and facilities are being implemented and maintained. If not, corrective action shall be taken to insure compliance.
1 Rev. 2 i
- - . . ._. _y.. . . .. _ _ _ _ _ . . _ . - . . _ . . . . . _ _ _ , _ _ _ , _ . _ . , , - , _ . _ .r._. , . . _ _ . _ . . . , _ . . ,_,,,,_._,__m.__ m.______,,___w.___.________, ___
4 . 2 . '2 Suroy Pond Area The Spray Pond and facilities will be
..~ ected and constructed by a Bechtel subcontractor. The subcontract specifications and drawings are to be made by Bechtel. These documents will define the control measures and facilities which the subcontractor will be required to implement and maintain. The subcontract will be awarded only to a sub-contractor capable of fulfilling these requirements;.
Below is a summary description of the require-ments that will be contained in the subcontract documents: All excavated materials shall be stored in a manner to limit erosion as determined by the Contractor (Bechtel) .
All surface runoff within the areas of earthwork and other areas disturbed by the subcontractor shall be routed to the Spray Pond excavation or diverted to the designated Debris Basin (See Drawing SK-C-394 ) . All pumped discharges shall be directed to the Debris Basin in accordance with Section 4.3.3 of this Control Plan. Access road-ways shall be covered with abrasion-resistant accregate as required to prevent objectionabl6 dost.
4.2.3 Schuylkill River Facilities The earthmoving and construction of the Schuylkill River Facilities-will be done by a Bechtel subcontractor. The subcontract specifications and drawings are made by Bechtel. These documents specify the basic requirements with which the subcontractor will be required to comply. The subcontract will be awarded only to a subcontractor capable A of fulfilling these rcouirements. A Master Erosion and C Water Pollution Contrgl Plan describing the control measures and facilities necessary to fulfill these re-quirements will be developed and implemented-by the subcontractor. The finalized measures A and facilities of that control plan, which have Q3 been reviewed and , approved artr in Appendix F.
B'elow is a summary description of some of the requirements that will be specified in the subcontract documents: The storm runoff shall be diverted from disturbed areas. The storm Rev. 3
. runoff discharges shall be controlled so as not to transport excessive sediment to the river or Possum Hollow Run. The excava-tions in and adjacent to the river shall be done in a manner to preclude excessive sedimentation in the river. Stripped and filled soils shall, as soon as possible, be protected by the use of seeding or compacted rock. Temporary access roadways shall be covered with abrasion-resistant aggregate.
4.2.4 Cooling Tower Area and Miscellaneous Earthwork The earthmoving activities covered under this section are.done by a Bechtel subcontractor.
The subcontract documents (see Specification 8031-C-5) applying to this work also covered nearly all the previous earthmoving at the Limerick site. Most of the requirements contained in this section were actually set into practice in the past.
Interceptor ditches shall be constucted to divert runoff from flowing onto areas of earthmoving. Interceptor and drainage ditches shall be seeded or covered with compacted rock.
All topsoil, loam, and other organic materials that have been stripped shall be stockpiled in a manner acceptable to the Contractor -%
(Bechtel). Fill materials shall be well' graded from fine to coarse and shall not contain topsoil or an excessive amount of fines. The fills shall be well compacted. Pumped dis-charges shall be routed to a holding pond or debris basin in accordance with Section 4.3.3.
The areal extent, and time of exposure for areas of earthmoving activities shall be minimized as much as practicable. The trench-ing and backfill operations shall be scheduled so that the length and duration of open pipe trenches is limited. Construction of roadways shall be scheduled so that operations for placement of pavement or abrasion-resistant aggregate as required for_ dust control are done shortly after start of earthmoving.
Rev. 2
i a 2 1
- Bechtel field personnel shall assure that !
earth stockpiles, earth fill slopes, and earth cut slopes are seeded upon completion of the applicable earthmoving activity. For subsequent excavation in grassed areas, after backfilling is completed, the surfaces shall be reseeded.
4.2.5 500 kV and 220 kV Switchyards Earthmoving for 500kV Switchyard is shown on Drawing SK-C-395. (Control measures to be incorporated later, prior to earthmoving activities) 4.3 Long-term Maintenance Program 4.3.1 General Requirements
~
All erosion and sedimentati~o'n con' trol measures implemented at the Limerick site before and after January 1, 1974 shall be continued and maintained throughout the period of construct-ion as needed to preclude deleterious erosion and/or sedimentation.
All of the control measures and facilities to be implemented and maintained at the Limerick site are not required to be limited to those specified in Sections 4.1 and 4.2 of this Control Plan. As the need arises, additional control measures and facilities shall be implemented and maintained in accordance with the references contained in Sections 2.1 and 2.2.
4.3.2 control of Traffic and Construction Activities Roads (within the site limits) and parking areas used by office and construction personnel for commuting to and from work shall be paved or covered at least with abrasion resis' tant material such as crushed stone. Roadways within the construction and laydown areas shall be covered with abrasion resistant material as required to prevent objectionable dust.
Rev. 2
o Insofar as practical, construction activities, Aucluding those of subcontractors, shall not disturb implemented erosion and sedimentation control measures and facilities. The disturbed measures and facilities shall be restored as soon as possible after the cessation of the disturbing activity.
4.3.3 Holding Ponds and Debris Basins Pumped sedimented water shall be discharged to debris basins or holding ponds. Discharging onto fill or cut embankments'shall be avoided.
The permanent underground storm drainage system contains an additional outlet (see Drawing 8031-C-13), other than the existing 36" outlet down-grade from Catch Basin No. S-5.3, that drains the eastern side of the Powerblock Area directly A3 to Possum Hollow Run. Because holding pond dis-charge water quality criteria do not apply to storm water runoff, this outlet shall be placed in service. However, the storm drains in the eastern Powerblock Area cannot receive pumped an6/or discharged water unless the water is tested as per Section 4.1.2.
Drainage ditches used to divert or convey runoff to holdina ponds or debris basins shall be seeded, covered with compacted rock, or paved.
Outside slopes of pond & basin. dikes shall be seeded or coveredzwith compacted rock.
Each pond' & basin shall be inspected after each storm and shall be cleaned out before the sediment collection reaches one third the
, storage volume of the facility as determined by the cognizant Field Engineer. For the storage volume designed for each pond & basih, see Appendix C. The sediment cleaned out shall be stockpiled or buried onsite or hauled offsite.
The stockpile shall not be located adjacent to channels or natural swales that drain directly to public waterways. Insofar as Rev. 3
possible, the stockpile shall be seeded.
If the stockpile is more than ten feet in height, its surface runoff shall be contained.
Sediment hauled offsite shall be done in accordance with the Rules and Regulations of the Pennsylvania Department of Environ-mental Resources.
- 4. 3. 4 Maintenance Review All of the disturbed areas, and the related control measures and facilities, shall be checked periodically by the cognizant Field Engineer for potential or evolving erosion and sedimentation problems. Any such problems shall be resolved and corrected in accordance with the procedure-described in Section 4.3.1.
5.0 PERMANENT CONTROL MEASURES AND FACILITIES 5.1 General Requirements Due to the long construction period and the extensive construction activities, it is impractical to install and implement the permanent control measures and facilities until toward the end of the construction period. The temporary control measures and facilities, as outlined in Section 4.0 to be implemented and main-tained throughout the construction period, will suffice ~-%
until permanent control measures and facilites are in-stalled and implemented. _
Those control measures and facilities used during construction,which will be~ beneficial on a permanent basis, such as interceptor ditches, shall be retained
. as permanent control measures and facilities. Those that will not be beneficial shall be converted at the end of their usefulness to comply with the requirements of Sections 5.2 and 5.3.
As construction activities come to an end in each area, the finished grading, with permanent drainage ditches and drainage control facilities, shall be implemented. Prior to commercial operation of Unit 2 of the Limerick Generating Station, the permanent seeding and landscapin'g shall be-implemented and planted to provide a final ground cover.
Rev. 1
(
=
Plant _
~ # Finished Grading and Drainage Control - Power 5.2 Facilities drainage The finished grading, drainage ditches and rdance d in control facilities permanent with the applicable shall be constructed drawings For a liste summaryin acco Section 2.2 of this Control Plan. description of some o criteria complied with refer to Appendix D.
5.3 Finished Grading and Drainage Control - Switchyards (To be incorporated later, prior to earthmoving i.
activities) 5.4 Permanent Seeding and Landscaping A landscape architect will be retained toAfter develop the the final landscaping for the project. Thislandscaping section, req be incorporated into this Control Plan.is reserved for landsc therefore, which will be issued during the final stages of >
construction.
l Rev. 1
0 0
0 0
e
(
Deleted f
.i a
i A-1 Rev. 1
~
APPENDIX B Conditions of Disturbed Areas during November, 1973 B.1 General The areal extent of the Limerick site is 180 acres. However, as explained below, its erosion and sedimentation problems are insignificant in comparison to its size. For the exist-ing disturbed areas, most of the required temporary control measures and facilities have been completed.
In the disturbed areas, the topsoil has.been removed and has been stockpiled. The topsoil stockpile has been seeded.
Also, all fill and cut slopes consisting of topsoil have been seeded. The seeding has effectively prevented accelerated erosion. With the exception of the Cooling Tower Area, ef-forts were made not to leave exposed any bare soil, which is easily susceptible to erosion, by placing non-erosive material such has crushed rock on top of the erosive surfaces.
The groundwater table is well below any disturbed areas so does not present any problems for erosion control. Due to the topography of the Limerick site, almost none of the disturbed areas are located downstream from any watersheds. For those that are, interceptor ditches have been provided to divert the flow.
With the exception of road and railroad crossings at Possum Hollow Run and Brooke Evans Creek none of the previous or .%
existing earthmoving activities have conflicted with streams of significant size. For the crossings at Possum Hollow and Brooke Evans, permits have been obtained from the Penn-sylvania Department of Environmental Resources. These cros-sings have been completed or abandoned and the streams re-stored to their pre-existing flow and bank conditions. The
- same is being done for those still under construction.
For the areal extent of the disturbed areas, with a brief description of the surface conditions, refer to the follow-ing table (Table B-1). For a detailed description of the disturbed areas, see Sections B.2, B.3, B.4 and B.5 of this Appendix.
TABLE B-1 AREAL EXTENT OF DISTURBED AREAS (NOVEMBER, 1973)
Area & Description Areal Extent (acres)
Subtotals Powerblock Area Rock Cuts & Crushed Rock Fills (Compacted) 22 Earth Cut Slopes (below RPV &
Pipe Shop Area) 1 B-1 Rev. O
Araa & Description Aranl Extent (ocroc)
Subtotals Paved Areas & Temp. Bldgs. 7 Excavated Holes (rock and earth) 10 40 220 KV Switchyard Rock Cuts & Crushed Rock Fills (Compacted) 9 9
Cooling Tower Area Earth Cuts & Fills (loose) '21 21 Construction Laydown Areas Surplus Fills Area (uncompacted) 5 North Storage Areas (compacted rock fills) 64 Northwest Corner (stripped bare &
gravel roads) 8 Batch Plant Area (compacted aggregate) 11 RPV & Pipe Shop Area (compacted rock fills) 10 RPV & Pipe Shop Area (grassed) 3 101 Disturbed Topsoil i
Stockpile (seeded) 3 RR Bridge-South Abutment (seeded) 1 4
Access Roads Evergreen and Plant Access (paved; ditches & slopes seeded) 2 Longview (paved; ditches & slopes seeded) 1 l
Site Access over Possum Hollow Run (Under Constr. - to be paved; ditches & slopes are compacted 1 rock or seeded) 2 5
TOTAL 180 B-2 Rev. 1
~
B.2 Powerblock Area B.2.1 Holding Pond (Under Construction)
Prior to the suspension of earthmoving on February, 1972 a holding pond was constructed to receive the pumped discharges from the excavated holes of the Powerblock Area. These pumped discharges-have been drained.directly to the holding. pond to prevent any flows from going to Possum Hollow Run.
After resumption of construction activities on July, 1973, work resumed on this holding pond to include the installation of concrete lining, inlet diffuser, outlet struccure and piping, and facilities for samp-ling and treating. (During the meantime another hold-ing pond has been constructed to temporarily receive flows during dewatering). For details of the long-term holding pond, refer to Drawing 8031-C-880.
B.2.2 Underground Storm Drainage System ne main lines of the underground storm drain piping and catch basins for the Powerblock Area have already been -
installed. For details of the permanent system, see Drawing 8031-C-13. For the already installed permanent piping, See Drawing FSK-M-33. We west and most of the north and south sides of the Powerblock Area drains to one 36" outlet dwngrade frcra Catch Basin No. S-5.3. We dis-charge to Possum Hollow Run is regulated by the butterfly valve at the Catch Basin. We east side of the Powerblock Area drains to one 36" outlet located just east of tha above outlet. Its discharge is unregulated.
Most of the surface runoff for the Powerblock Area drains to this underground storm drain system. Thus, the length of overland flow is reduced, which is turn reduces the amount of possible erosion.
B.2.3 Surface Conditions The Powerblock Area has been graded nearly level, so is not subject to high velocity runoff. Also, much of the rainfall is infiltrated whic k *ecreases the volume of runoff.
The rock line is close to the natural ground surface.
Thus, most of the cut grades and cut slopes in the Powerblock Area are in rock.~ The cut slopes show very little evidence of erosion. The cut slopes below the Cooling Tower Area drain to the excavation for the Circ. Water Pump Structure. For the cut slopes below the RPV and Pipe Shop area, interceptor ditches have B-3 Rev. 1
- been provided. Some of the runoff from the RPV and Pipe Shop Area is diverted to an undisturbed area above Possum Hollow Run, and some is diverted to downdrains which in turn drain to the Also the earth installed under-portions ground storm drain system.
of the cut slopes below the Pipe Shop area have been seeded.
The gradually sloped graded area east of the temporary construction buildings has been paved for parking. The plant access road has been paved, and its banks and side drainage ditches have been seeded.
The fill grades and fill slopes of the Powerblock Area co'nsist of broken rock taken from the excavated areas.
The fills are well compacted and the fill slopes show no sign of erosion. The roads and side drainage ditches going down along the fill slopes are also well compacted. (These road surfaces are temporarily paved and culverts have been provided.) Moreover, there is no evidence of sediment movement on the natural terrain below the fill slopes.
From past observations of the storm water discharging to Possum Hollow Run from the outlet of the installed underground storm drain piping, it has been found that intermittently this water has a reddish-brown colora- The tion. The probable cause for this is as follows:
.u '
rock fills and rock cuts consist of reddish-brown silt-stone. The addition of traffic to surface runoff causes the rock surfaces to disintegrate slightly.
The storm runoff carries some of the resultant fine material into the underground storm drain system. To partially alleviate this problem, abrasion-resistant aggregate imported from off-site has been placed on roadways. However, due to future construction activi-ties in the Powerblock Area during storms, this problem is expected to continue.
B.3 220 KV Switchyard Like the Powerblock Area, the 220 KV Switchyard has been graded nearly level thus reducing the velocity and volume of runoff. Also, like the Powerblock Area, the graded area of the 220 KV Switchyard consists of rock cuts and compacted rock fills. The graded area is presently being used for Roadways serving the storage of construction materials.
area have been covered with abrasion-resistant aggregate.
Surface runoff from this area, as presently graded and used, does not present any problems of erosion and sedimentation.
Rev. 1 B-4
. B.4 Cooling Tower Area The Cooling Tower area excavation consists of bare soil and rock. The fills are not compacted. No efforts have been made to protect or seed the area. However, the area is level so that a majority of the rainfall either infiltrates or is retained on the ground surface. Any runoff that occurs is at a very low velocity, so does not create any significant amount of erosion. Moreover at the present time there are no activities in the area to increase the erosion.
B.5 Construction Laydown Areas -
The " surplus fills" area consists of excavated material suitable for compacted fills. There has been some erosion and sedimentation in this area, but because of its areal extent (5 acres) and the gradation of the material, the adverse effects have been negligible.
The north storage areas have been cleared and graded. A few designated areas containing trees and shrubbery have been left undisturbed. The graded areas consist of compacted fills of broken rock taken from the Powerblock excavation.
Service roadways in the area have been protected with abra-sion-resistant aggregate from off-site to prevent the rock from eroding during the combination of traffic and storm run-off. For the most part, these storage areas are graded level or gently sloped to prevent a high velocity runoff. However, a strip parallel and adjacent to the Plant Access Road and the Sanatoga Road has in the past been subject to a signifi-cant amount of erosion and sediment movement. The primary causes for this are high velocity flows coming from side drainage ditches of the Plant Access Road and from a culvert which takes runoff from storage areas. This strip drains to a culvert that crosses Sanatoga Road and in turn discharges toward Sanatoga Creek. However, since the resumption of construction activities on July, 1973, this strip has been covered with compacted rock which so far has effectively corrected the problem.
At the northwest corner of the site, an area to be used for storage has been stripped bare. Also some earth material has ,
been placed and compacted to level the area. The area is l surrounded and crossed with abrasion-resistant aggregate sur- 1 faced roads. Thus, rainfall on the area is infiltrated and i
retained in the area. However, the fill slopes show signs i
of erosion.
J 1
B-5 Rev. 1
The Concrete Batch Plant Area has been cleared and entirely ouimuccu witn anrasion-resistant aggregate. Also, the area is practically level which prevents a high velocity runoff.
The majority of the area drains toward a grassed waterway which in turn drains toward Possum Hollow Run. The grassed waterway shows no signs of erosion or sediment movement.
The majority of the RPV and Pipe Shop Area consists of compact-ed rock fill. This portion of the area has been graded nearly level and abrasion-resistant aggregate has been used for the roads. A grassed area below the Pipe Shop has been relative-ly undisturbed. This grassed area has a significant slope which slopes toward cut slopes above the Powerblock Area. The grassed area shows no signs of erosion. As previously described in Section B.2.3 of this Appendix, interceptor ditches have been provided to divert the runof f from the RPV and Pipe Shop Area from going onto the cut slopes of the Powerblock Area.
For the run-off that is diverted to the undisturbed area above Possum Hollow Run, a culvert has been provided to run this flow from the RPV and Pipe Shop area to the undisturbed area.
At the discharge end, the culvert extends from the ground surface. No outlet or baffles have been provided. However, there is no evidence of scour on the natural terrain below.
B-6 Rev. O
, APPENDIX _C Design Criteria - Holding Ponds and Debris Basins C.1 General The storage volume of each of the ponds &insins .is based on the design criteria for debris basins as set forth in the Montgomery County Handbook. The sizes of the principal and emergency spillways an3 based on the design criteria for r
sediment retention basins as set forth in the EPA Guidelines.
Storm runoff is deterr.ined from the Rational Formula (Q= CIA) .
The design data for storm runoff calculations are based on a 10-year frequency storm and on the soil cover conditions of the tributary areas during the construction period. The intensity is taken from U.S. Weather Bureau Technical Paper No. 25, Rainfall Intensity-Duration-Frequency Curves, Decem-ber 1955, for Reading, Pennsylvania.
The Control Plan requires cleanout of the ponds & basins when-ever the remaining storage volume is two thirds the design storage volume.
C.2 Holding Pond for Powerblock Area For details and dimensions of this holding pond, see Drawing 8031-C-880. The suction and discharge lines serve as the principal spillway, and the overflow pipe serves as the emergency spillway. The following paragraphs outline the -4 actual storage and flow capacities of the pond.
The storage capacity of the holding pond (below the overflow pipe) is 54,800 cu. ft. (410,000 gal.). For three possible cases in which a watershed area is tributary to the pond, the following table (Table C-1) lists the watershed inches (depth of runoff for the tributary area) that the pond is
- capable of receiving for both whenever it has been cleaned out (full capacity) and whenever it requires cleaning out (2/3 capacity). For background information regarding the areal extent, refer to Table B-1 of Appendix B and to Draw-ing SK-C-392.
TABLE C-1 Areal Extent of Watershed Inches Watershed Inches Watershed (acres) (Full Capacity) (2/3 Capacity)
Case 1 10 1.50 1.00 2 30 0.50 0.33 3 38 0.40 0.26 i
C-1 Rev. 2 I
Case 1 is only for discharges from sumps in excavated areas collecting surface drainage. Case 2 is for the discharges from excavated holes plus runoff from the underground storm drainage system installed before January 1, 1974 (see Draw-ing FSK-M-33). Case 3 is for discharges from excavated holes and/or roof drainage plus the runoff from the completed underground storm drainage system (see drawing 8031-C-13).
Case 3 includes the runoff that is required in Section 4.4.3 of the Control Plan to be diverted to Catch Basin No. S-5.3.
For all cases the holding pond is cleaned out before its storage capacity is reduced to 0.25 watershed inches as re-quired by the Montgomery County Handbook.
The calculated runoff for Case 3 entering the holding pond is 51 cfs. The capacity of the holding pond's overflow and discharge pipes is greater than 51 cfs. .
C.3 Debris Basin for Cooling Tower and Spray Pond Areas For details and dimensions of this debris basin, see Drawing SK-C-394. This basb2 is constructe'd similarly to debris
~
basins as specified in the Montgomery County Handbook and to sediment retention basins as specified in the EPA Guidelines.
The maximum possible areal extent of the watershed areas tri-butary to the buin is 47 acres. This includes the disturbed Cooling Tower and Spray Pond are'as (38 acres) plus undisturbed areas tributary to the pond (9 acres). In order to receive 0.6 watershed inches during full capacity, the design storage volume of the bashi is 103,000 cu. ft. The combined capacities of the principal and emergency spillways are able to pass a peak runoff of 63 cfs.
=
-4.
s i ,
l ~ .
if s
m , ,
\
' C-2 Rev. 2 l
l
i APPENDIX D General Practices and Design Criteria-Permanent Drainage D.1 General The practices and design criteria outlined in this Appendix are implemented on the applicable drawings for the permanent plant facilities.
D.2 Finished Grading The access roads, service roads, and parking areas are re-quired to be covered with asphalt pavement. Drainage ditches are provided along the edge of the paved areas to properly convey runoff. Culverts are provided for ditch crossings.
The graded areas are ara 4ed tg a minimal _sippe. Fill Slopes '
and earth cut slopes hhve maximum slope of 2:1. Rock cuts have maximum slope of lil.
For the Powerblock Area, an underground storm drainage system is being installed to reduce the amount of surface runoff.
D.3 Storm Runoff Design Criteria Storm runoff is determined from the Rational Formula (Q= CIA).
The design data for storm runoff calculations are based on a 50-year frequency storm and on the permanent soil cover conditions of the tributary areas. The intensity is taken from the U.S. Weather Bureau Technical Paper No. 25, for Reading, Pennsylvania. The curves for Philadelphia are al-most identical to those of Reading. Since the Limerick site is located between Philadelphia and Reading, the curves for Reading are accurate enough to be used for storm runoff cal-culations at the Limerick site.
The capacity of ditches, culverts, and underground storm pipes are determined from the Manning Formula (Q = l 49 n AR2/3 Sl /2). The designed channel flow capacities are equal to or exceed the calculated storm runoff.
D.4 Drainage Ditches and Interceptor Ditches
\ Interceptor ditches are provided to prevent sheet flow over fill and cut slopes. Drainage ditches are provided to pro-perly convey the runoff from graded areas. The drainage and interceptor ditches are V-shaped with 2:1 side slopes.
The ditches are being graded at minimum practical slopes to keep the velocities to a minimum.
Within the permanent graded areas, the slopes of the ditches are less than 0.6%. Also, within tite permanent graded areas, reinforced concrete ditch checks, with riprap downstream, are being provided to accommodate dif ferences in elevations.
D-1 Rev. 1
J
- In the crccc rectored to natural conditions, the slopes of the drainage and interceptor ditches are graded to less than 2.5%. In some cases, the access and service roads are graded to as much as 8.0%. For these cases the tributary areas of the side drainage ditches are small in areal extent so that the amount of runoff is also small.
D.5 Outlets for Storm Runoff Discharges All drainage and interceptor ditches discharge to underground pipes by way of catch basins or culvert inlets. Downdrains are provided to prevent discharges flowing on slopes. Wherever possible, concentrated runoff discharges are discharged di-rectly to sizeable natural water courses.
At each storm runoff discharge, a baffled outlet is being provided to dissipate the energy. Also, riprap is required to be placed downstream from each outlet to further dissipate the flow and to prevent scouring.
- t, D-2 Rev. 1
\
4 APPENDIX E Reference Drawings for Information The following drawings are referred to for assistance in the deve-lopment and understanding of ttis Control Plan.
Drawing 8031-C-1 Site Plan i Drawing 8031-C-4 Soil Borings Plan Drawing 8031-C-5 Rock Contours Perkiomen Makeup Water System Location i Drawing 8031-C-3810 General Plan and Profile Drawing FSK-M-33 As Built Storm Pipe Drawing FSK-C-324 Temporary Drainage for Elant Area As Built Drawing FSK-G-35 Proposed Construction Parking Facilities E-1 Rev. O
,
- APPENDIX F,
,. Master Erosion and Water Pollution Control Plans F.1 EROSION CONTROL:
F.1.1 During clearing and grubbing, work will be contained with-in the areas defined in the plans. Hay bales will be used and staked to protect readily erodible soils.
F.1.2 Where necessary, drainage ditches and/or slope drains will be constructed.
F.1.3 Seeding and other methods will be employed as necessary to control erosion.
F.1.4 Should construction operations be suspended for any reason whatsoever, all exposed areas will be properly protected by using any but not limited to the following:
hay bales, seeding, ditching an/or other methods neessary.
F.2 WATER POLLUTION CONTROL:
F.2.1 Pump House Area:
F.2.1.1 Dredging, excavation and/or backfilling, will be done after the cofferdam has been installed and prior to its removal. When necessary, an anti-pollution curtain will be deployed during any of the mentioned operations.
F.2.1.2 Water collected in the area of the excavation created for construction at the pumphouse will be pumped from the area when necessary for construction activities as determined by J. E.
Brenneman Co. Project Manager.
F.2.1.3 Discharge from pumps will be to retention pond which will be constructed inside the cofferdam cell (Refer to Drawing prepared by S. T. Hudson Engineers, Inc., File No.PC-1217 Drawing No. 1, Revision 2 dated November 9, 1977.
F.3 DIFFUSER AND CHANNEL STABILIZATION AND BLOWDOWN AREAS F.3.1 Water inside the cofferdam of diffuser and/or channel stabilization areas will be pumped to filtering system described on J.E. Brenneman Co. Drawing B-4(SC-55-9-2).
F.3.2 During placement of backfill concrete pumps discharge will be placed in shore or on island for additional filtration.
P-156/4 F-1 Rev. 3
- 1 t
. l
! F.3.3 Water at blowdown trench will be directed into temporary
, milt basins as approved by the Contractor and slopes will be lined with hay bales to arrest erosion.
F.4 MISCELLANEOUS POLLUTION CONTROL:
F.4.1 Fuels and lubricants will be stored and dispensed near our existing trailers, located between the Railroad and Road "A". A 55-gallon capacity container will be used to hold liquid wastes and will be located thereat.
F.4.2 Where streams have to be forded, temporary bridges or culverts will be used if required.
F.4.3 Portable sanitary facilities will be used and serviced regularly.
F.5 AIR POLLUTION CONTROL:
F.5.1 Contruction access and haul roads West of Railroad shall be maintained so as to minimize dust by sprinkling water as necessary.
F.5.2 Other methods as necessary to control air pollution will be employed.
F.6 RELOCATION AND MAINTENANCE OF EXISTING UTILITIES:
F.6.1 Existing utilities found along and/or inside construction areas shall be properly protected, relocated and/or '4 maintained. Proper notification shall be made for any utility found inside work areas prior to relocation or proceeding with work thereat, a
4 e
2-156/4 F-2 Rev. 3 i
4
- w. ,I