Integrated and collabora.ve approach among Technical Agencies, Industry and University: the Sarroch case study (Sardinia, Italy)

Transcription

1 Second joint Workshop, Berlin th May A European policy framework on contaminated land: Enabling integrated land management and promo&ng sustainability. Integrated and collabora.ve approach among Technical Agencies, Industry and University: the Sarroch case study (Sardinia, Italy) Marco Pe.Aa, Dipar&mento Scienze della Terra, Università Sapienza di Roma Maurizio Guerra, ISPRA Roberto Pecoraro, versalis (eni) Mauro Congiu, versalis (eni)

2 Background The remedia+on plan of the versalis plant of Sarroch, based on Pump&Treat, has been approved by the Ministry of Environment (MATTM) on May 2010 Since 2008 about 80 wells are pumping a total discharge of about 80 m 3 /h; AIer MATTM requests, the Regional Environmental Agency (ARPAS) and the Na+onal Ins+tute for the Environmental Protec+on and Research (ISPRA) released some notes evidencing a poten+al limited efficiency of the pumping system on the shallow por+on of the aquifer, where no sufficient lowering of water table have been recorded, with the possible risk of contaminant plumes to move towards the environmental target (the shoreline and the sea) Since 2012 Versalis required to the Sapienza University the implementa+on of a flow simula+on model, based on an updated conceptual model of groundwater flow and consequent addi+onal inves+ga+ons; In the last two years, ac+ons for op+miza+on of the hydraulic barrier have been implemented, based on a common discussion and agreement with the Public Agencies, driving to the last MATTM note dated March 5, 2014, where the results of the mathema+cal model have been accepted, indica+ng the further steps for the remedia+on.

3 Ini.al problem Pumping rates and well performances were limited for reaching the required water table deple+on (<0 m asl); this can by due to: i) separate shallow aquifer system? ii) ver+cal heterogeneity? iii) well efficiency? iiii) hydraulic barrier management? First ac+on: verifica+on of the efficacy of the hydraulic containment (there are poten+al environmental damages?) : - Simula+on model - Tests on sea water/air interface Answer: the recorded piezometric trend does not highlight possible contamina+on plumes reaching the environmental target

4 First ac.ons NEW INVESTIGATIONS " New 16 shallow pumping wells (S19- S34) " New 13 monitoring wells between new wells (EMW59- EMW71) " Addi+onal 14 monitoring wells for exis+ng pumping wells " Addi+onal characteriza+on by new 8 deep monitoring wells to 50 m b.g.l. Total withdrawal includes " 79 pumping wells (including the new 16) " About 100 monitoring wells " Draining trench in the lower area, close to the shoreline " 8 monitoring wells with low- rate pumping in the lower area AREA 2 AREA 4 AREA 3 AREA 1 LOWER AREA

5 Methodological approach: road map shared with Public Authori+es (ISPRA) Versalis opens a technical discussion with Public Autori+es for jointly evaluate the technical solu+ons and the results obtained by the addi+onal field surveys, instead of postponing the official advice and/or approvals to the submission of the final documents Consequently, Authori+es were not only regularly updated, but at the same +me technical staff of each subject jointly worked and shared the programme So, observa+ons and comments on the results have been received during the field ac+vi+es, instead aier reading final reports; in detail, the simula+on hydrogeological model has been conceived and developed with the aim for represen+ng groundwater flow, rather than for demonstrate the hydraulic containment Several mee+ngs have been scheduled at different steps of the project, un+l the presenta+on of the official report on the hydrogeological model, in January 2014 In March 2014, the MATTM released some comments accep+ng the model and requiring addi+onal details for the op+miza+on of the remedia+on plan

6 Results: groundwater lowering along the hydraulic barrier Comparison of piezometric maps of March 2012 (in green) and April 2013 (in red) along the central part of the hydraulic barrier (new wells from S19 to S31) 6

7 The detailed conceptual model Geological and Hydrogeological background to be implemented Volcanic Rocks Recent alluvial/detrital deposits Granites

8 Before the numerical model, the conceptual model needs to be refined: 1) Geological survey, drillings, geotechnical tests 2) New 16 shallow wells (S19- S34) 3) 11 Lefranc tests 4) 41 slug tests 5) 14 pumping tests on exis+ng wells 6) 28 step- drawdown test on exis+ng wells 7) First numerical model of the site 8) Environmental isotope analysis (about 50 samples) to iden+fy groundwater origin 9) Monitoring of each well func+oning 10) Analysis of the management of each wells 11) New three cluster monitoring wells having different depth 12) Water levels in wells: con+nuous monitoring 13) Simula+on model for pumping wells management 8

9 Isotopic analysis: different origin of groundwater and contribu+on from industrial pipelines canale_nord

10 Cluster monitoring wells: differences in hydraulic heads between shallow and deep por+ons of the aquifer Screens - Shallow: 3-20 m bgs - intermediate: m - Deep: m

11 Salinity logs: the role of the sea- water channel (looking for marine intrusion and finding canal losses) Electric conduc+vity log in monitoring wells EMW29 (A) and ZMD21 (B). Red line: trace of the underground canal 11

12 Results: Well opera.on (pumping periods) (monitoring and modifica+on) Previous opera+on system A c t u a l opera+on system LSH Mean opera+onal water table level (Lset) LSH Mean opera+onal water table level (Lset) LSL LSL

13 Results: Water table monitoring (groundwater oscilla+on due to natural and human changes, as aquifer recharge and pipeline losses) BS28

14 Results: groundwater lowering in the cri+cal area Lowering of about 2 m of the water table has been obtained and the zero (0 asl) has been reached along the hydraulic barrier; nevertheless, close to the underground channel withdrawals are replaced by con+nuous losses from the canal.

15 Results: water table lowering along the hydraulic barrier

16 New tool: the simula.on model for op.miza.on 5 slices and 4 layers: DEM, - 5 m asl, - 35 m asl, - 45m asl, - 70 m asl

17 How to proceed a^er sharing process: Quan+fica+on of canal losses m 3 /d m 3 /d (SeAore B1) (SeAore C1) m 3 /d (SeAore B) m 3 /d (SeAore C) August 2013 simula.on results

18 Next steps: Reduc+on of water pipeline losses and interven+on on the Underground Canal where the highest amount of losses are concentrated Geoelectrical tomographies highlighted the zones along the canal where the losses to the aquifer are probably concentrated

19 Next steps Model op+miza+on procedure (uncertainty reduc+on) Upscaling of knowledge at detailed scale (single well), by pumping tests and evalua+on of the best pumping rate) Simula.on of November 2013

20 Perspec.ves: remedia+on based on sharing process In terms of ELD, this experience can represent a valid example where Competent Authori+es and Operators have applied as best prac+ce an integrated and collabora+ve approach, which is based not only on technical requirements, but also on con+nuous shared discussions between the par+es, in order to improve their understanding, and take the precau+onary measures needed to avoid environmental problems thanks to the adop+on of the numerical simula+on model as management tool. The common goal of the study is to achieve a deep knowledge of the aquifer- hydraulic barrier system, and to suggest the appropriate measures for the op+miza+on of P&T system. The proposals for the adjustment/op+miza+on of the P&T system were officially presented to the Authori+es for they approval along with the result of the groundwater flow simula+on. This has resulted in +me savings and likely in environmental benefit. Therefore, this model can be used as a reliable opera+ve and working tool to monitor and to manage the hydraulic barrier, evalua+ng pumping rates, expected piezometric drawdown, consequences of addi+onal ac+vity (losses reduc+on, marine intrusion control, etc.) and consequently the efficiency of the hydraulic containment, in agreement with the Authori+es expecta+ons. It should be emphasized that as the aquifer- hydraulic barrier can be considered a dynamic system and of course the study is in progress.

21 That says it in a nutshell THERE ARE TWO POSSIBILITIES: A. The hydrogeological (simula+on) model can be built by the Private Company and frequently the Authority can assume that the aim is to unilaterally demonstrate the efficency of the pumping system B. Otherwise, as in this case, the aim of the model realized by versalis is to carefully represent and evaluate groundwater flow and the effects of the hydraulic barrier, using an itera+ve process which tends to minimize unavoidable uncertain+es, driving to a powerful tool ready for a dynamic management of the remedia+on ac+vi+es In the first case, there is the risk that the model can be bent to the project manager ini+al idea, while in the second case the model can frankly develop from available data, leading to real and verifiable results

22 Thank you for your aaen.on!

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