Stage One North Detail Refer to Geoscience Drawings

Transcription

1 Stormwater and Leachate Treatment Stage One North Detail Refer to Geoscience Drawings Morning glory bell mouth spillway Pe r i me ter d Spreader Bar rain Sediment Retention, Stormwater Detention Pond Area = 1940m2 To ea str ce ss Tr ac k Ac Inlet and outlet at opposite ends of leachate storage pond in case treatment is proposed. Gravity leachate trench laid on clean fill at RL Leachate line gravitating to WCC sewer Leachate Line (150 ID) Excavated into landbridge at RL of 142 Manhole with manually actuated valves C and D Landfill - Owhiro Bay, Wellington Location of stormwater and leachate storage ponds and associated pipework Perimeter drain SIZE Drawn by Date A3 TJ 5 March 2014 SCALE As shown After Geoscience (2014) SHEET REV 5 1 of 17 m Leachate Storage Pond Pumping chamber for leachate collector S Decanting gravity outlet from leachate pond

2 Leachate Storage Pond Sections Stage 1 North batter slope HDPE Liner Current Landbridge Constructed Earth bund 2.00 Stage 1 North batter slope Gravel Leachate Trench 7.06 Pump well HDPE Liner Pipe to be placed with cut through land bridge* Zone of Inert fill Current culvert HDPE Liner 0.15 Packed with bedding material C and D Landfill - Owhiro Bay, Wellington Leachate Storage Pond Sections *Exaggerated for drawing purposes A3 MD 5 March SCALE 1:300 SHEET 2 of 17

3 Stormwater and Leachate Storage and New Pipework Perimeter Drain Decanting Outlet Leachate storage Sediment Retention, Stormwater Detention Pond Area = 1940m 2 Piped section nominally 150ID subject to specific design Stormwater Line Bund to stop emergency overflow crossing Landfill Rd Piped section nominally 900ID subject to specific design Existing sewer line (after WCC GIS) Tie into WCC sewer as shown on sheet 17 Man Hole Point of re-entry into culvert under option 2 Valve Energy Dissipating Man Hole Culvert under landfill road Current culvert (approx. location) Man Hole 150mm ID pipe placed through land bridge at RL of 142 Man Hole Man Hole C and D Landfill - Owhiro Bay, Wellington Proposed new stormwater and leachate lines and tie in points TJ 5 March 14 3 SCALE As shown SHEET 3 of 17

4 Overview of C and D Landfill Final Surface Leachate and Storm Water Plan Extension of culvert Temporary perimeter drain (to be constructed at 1:100) Permanent Drop structures (as detailed in sheet 10) Culvert Extension Area of inert fill Final Stormwater Pperimeter Drainage Plan Stage 1 N A3 MD 9 December SCALE SHEET 4 of 17

5 Overview of C and D Landfill Final Surface Leachate and Storm Water Plan Tie into stream and stage 1W drainage subject to specific design, similar to section 4, sheet 9 Permanent Drop structures (as detailed in sheets 13 & 14) Discharge to stormwater pond on landbridge Temporary perimeter drains Existing pipe structure (constructed during Stage 1N) Stormwater Perimeter Drains Plan Stage 2 A3 TJ 5 March SCALE SHEET 5 of 17

6 Overview of C and D Landfill Final Surface Leachate and Storm Water Plan Stormwater Perimeter Drain Plan Finished Surface A3 TJ 5 March SCALE NTS After WCC SHEET 6 of 17 Explanatory Notes: Perimeter Drains to be moulded to final landfill surface (ref: Geoscience ) In areas where a gradient of 1:100 can not be achieved, the perimeter drain will be piped and benched to the haul road. Perimeter drain to run parallel with final landfill surface (piped and benched) Permanent Perimeter Overland Drains Stormwater pond Area of Cleanfill Indicative only (refer to Geoscience drawings) Perimeter drain to run parallel with final landfill surface (piped and benched) Perimeter drain with a slope of 1:100 (arrows indicating flow direction) Flow piped across side channel on road Stream

7 Conceptual Model of final perimeter drains Concrete Skin, for cleaning and maintenance purposes SOUTH NORTH SOUTH NORTH Perimeter Drain Compacted Local Material GCL Liner (if porosity is not low enough) Surrounding material (Bedrock, Colluvium) Insitu soils ca. 0 2m thick Torlesse Greywacke bed rock RL260 RL270 Landfill capping Landfill? RL245 Base not seen? Colluvium infilled Paeleogully Current C and D Landfill A A Example area of cross section A Leachate Drain A Horitonian overland flow Horitonian overland flow Insitu soils ca. 0 2m thick Insitu soils ca. 0 2m thick Subsurface flow (at interface between soil and bedrock) Torlesse Greywacke bed rock 10m Cut into existing face at 60 degrees max cut slope Cut away section Perimeter Drain 5m Compacted surface Final Landfill Capping Final Landfill Capping Compacted surface Cut away section 5.5m Cut into existing face at degrees max cut slope Perimeter Drain Colluvium infilled Paeleogully Bored Drains Cut to provide bench (max cut slope 60 degrees and backfill and stabilise to 60 degrees fill slope Flow to be captured by base leachate drain Diagram is not to scale, and has been exaggerated for illustrative purposes For more detailed design of drains refer to sheets 8 and 9 Conceptual Model of finished (stage 3) drain system and surface A3 MD 23 October 13 0 SCALE NTS SHEET 7 of 17

8 Cross section of staged perimeter drains Section 1 Perimeter road / drain Cut in rock Section 2 Perimeter passing bay / drain Cut in rock 45.0 Cut slope Original Surface Cut slope Original Surface Fill Fill bench supported by buttress to landfill surface or local engineering design (where required terramesh green or similar) 20.0 Cross Sectional detail of perimeter drains A3 MD 31 October 13 0 SCALE 1:100 SHEET 8 of 17

9 Cross section of staged perimeter drains 45.0 Section 3 Perimeter road / drain Cut in colluvium Tied back timber pole wall or equivalent Section 4 Perimeter road / drain At intersection with current stream Cut into rock Bored drains Cut slope Original Surface 25.0 Subsurface drain to feed into perimeter drain Rock Anchor 80.0 Original Surface Fill bench supported by buttress to landfill surface or local engineering design (where required terramesh green or similar) Cut slope 2.00 Lip to stop overflow where drains intercept stream paths Fill bench supported by buttress to landfill surface or local engineering design (where required terramesh green or similar) Socketed into underlying rock Assumed top of insitu greywacke Cut to provide bench Cut to provide bench Example of bored drains observed at Muldoons Corner, Rimutaka Highway (SH2) 06/12/13. Cross Sectional detail of perimeter drains A3 MD 30 October 13 0 SCALE 1:100 SHEET 9 of 17

10 Cross Section Detail of drop structures of final landfill face A B Ø A 4 B Note: Slope angle and length as per detail provided Geoscience drawings Aqua Duct Fluming Ø C C Cross Sectional Detail of Landfill face A3 MD 5 March SCALE NTS SHEET 10 of 17

11 Sections of drop structures Final Landfill Surface 1.00 A A Final Landfill Surface 2.00 C C Ø0.60 Subject to specific design Final Landfill Surface 2.00 B B Cross Sectional Detail of Landfill face A3 MD 1 November SCALE 1:100 SHEET 11 of 17

12 Stage 1N (A) Temporary link to existing culvert termination point Stage 1N (A) SIZE Drawn by Date A3 TJ 5 March 2014 SCALE After Geoscience SHEET REV 0 12 of 17

13 Stage 1N (B) View specified Detail Head of Culvert Drop structure to account for recontoured slope = storm water flow direction Stage 1N (B) SIZE Drawn by Date A3 TJ 5 March 2014 SCALE After Geoscience SHEET REV 0 13 of 17 Sediment retention pond placement subject to specific design Temporary link to existing culvert termination point

14 Ex tn of c ul ve rt Stage 1N (C) de e b To e lop e v ng illi f ith w d Temporary link to existing culvert termination point Slope contoured to N. to allow drainage Stage 1N (C) SIZE Drawn by Date A3 TJ 5 March 2014 SCALE After Geoscience SHEET REV 0 14 of 17

15 Stage 1N (D) Stream flow entering cutoff drain Temporary link to existing culvert termination point Stage 1N (D) SIZE Drawn by Date A3 TJ 5 March 2014 SCALE After Geoscience SHEET REV 0 15 of 17

16 Conceptual design of sediment retention pond Reinforced bank to allow head to develop Decanting outlet device Sediment Retention pond designed to GWRC ESCP guidelines pond set into fill Stage in fill slope. Contoured as per geoscience drawing D Conceptual design of Sediment Retention Pond at toe of Stage 1N A3 TJ 5 March SCALE SHEET 16 of 17

17 Sewer Line Centrate Line Leachate from WCC Stage 1 WCC suggested Location for C and D leachate tie in New Sewer line 150 ID (Approx. Location) Gas Treatment Device Point of flow monitoring Old Yard C and D Landfill Ltd General Arrangement of WCC sewer manholes at the toe of Southern Landfill mat@nzet.net.nz A3 MD 5 March SCALE As shown After GWRC 2013 SHEET 17 OF 17