💧 Monitoring Wells · Aquifer Sampling · Glyphosate · Potability · HPLC-MS/MS · Table 2 Decree 831/93

Underground Water

Groundwater monitoring well construction, aquifer surveillance, drinking water potability and contaminated site groundwater characterisation.

Biogroup provides a complete groundwater service — from the design and construction of monitoring wells (phreatimeters) and hydraulic levelling to representative low-flow sampling, full analytical characterisation per Decree 831/93 Table 2, and specialised analysis of pesticides and herbicides by HPLC-MS/MS — including glyphosate and AMPA at sub-ppb detection limits.

Whether monitoring a production well for potability compliance, characterising a contaminated plume at a Phase II site investigation, or maintaining a long-term aquifer surveillance network — Biogroup integrates field work and in-house analytical capability into a single, accountable service.

Well construction
Any geological formation
Glyphosate
HPLC-MS/MS · sub-ppb
Table 2
Decree 831/93 full panel
+35 years
Groundwater expertise
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Field-to-lab integration
Biogroup installs the phreatimeters, collects the samples and analyses them in-house — eliminating the chain of custody breaks and communication failures that arise when field crews and laboratories are separate organisations. One team, one accountable result.
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Glyphosate and herbicide specialisation
Glyphosate and AMPA in groundwater by HPLC-MS/MS at sub-ppb detection limits — critical for the Pampa region where intensive soy agriculture makes these the primary groundwater contamination concern. Full pesticide multi-residue panel available.
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Regulatory comparison
Results reported against Decree 831/93 Table 2 (groundwater quality guidelines), Argentine Drinking Water Code (CAA Resolution 494/94, SMR-Q), WHO drinking water guidelines and EPA MCLs — accepted by SAyDS, OPDS and provincial authorities.
Monitoring well design and construction — phreatimeters for all geological formations
A phreatimeter network is only as good as the wells it is built on
Well design — screen interval, slot size, casing diameter, gravel pack specification and surface completion — must be engineered for the specific lithology, aquifer depth and sampling objective. Poorly designed wells produce non-representative samples and unreliable piezometric data.
🔩 Well design
Engineering of screen interval, slot size (0.2–0.5 mm depending on formation grain size), casing material (HDPE or PVC Schedule 40/80), annular seal design and surface completion — all matched to lithology, target depth and intended use (contaminant monitoring vs. potability).
⚙️ Drilling and installation
Construction of monitoring wells in any geological formation — sandy, silty or clay-rich unconsolidated sediments and fractured rock. Hollow-stem auger, mud rotary or direct push depending on formation, depth and presence of volatile contaminants.
🪨 Gravel pack and annular seal
Placement of filter pack gravel around the screen section and bentonite seal above to prevent vertical leakage between aquifer horizons — the elements that determine hydraulic isolation and sample representativeness.
🛠️ Well development
Air lift, surge and pump development to remove drilling fluid, fines and disturbed material from the gravel pack zone — until turbidity and field parameters stabilise. Documented with development records.
🪣 Exploratory trenches (calicatas)
Manual or mechanical excavation of trenches for shallow visual inspection of near-surface stratigraphy, identification of fill materials, buried structures and surface contamination zones inaccessible to drilling.
📍 GPS positioning and optical levelling
GPS coordinate recording of each well top and ground level. Optical levelling (level instrument and/or total station) of all well reference elevations relative to a common datum — the foundation for accurate water table contouring.
Piezometric level measurement and aquifer monitoring
Synchronous piezometric measurements — the data behind the water table map
Electronic interface probe · 0.001 m sensitivity · decontaminated between wells · GPS-positioned
Measurement protocol
Depth to water is measured in each well using an electronic interface probe with 0.001 m sensitivity — recording depth to water/product interface (for NAPL detection) and depth to bottom of well. All measurements made synchronously in a single day to ensure water table data reflects true hydraulic conditions at one moment in time. All equipment decontaminated between wells to prevent cross-contamination.
What is produced from level data
✓ Water table elevation at each well (from levelled reference)
✓ Potentiometric surface contour map (equipotential lines)
✓ Groundwater flow direction arrows
✓ Hydraulic gradient calculation
✓ Free-phase NAPL thickness estimation (if applicable)
✓ Seasonal variation documentation
✓ Input data for MODFLOW groundwater flow model
Groundwater sampling — representative low-flow protocol
Representative sampling is the most critical quality control step in groundwater monitoring

A groundwater sample is only representative of aquifer water if the stagnant water that has been standing in the well casing has been removed before sampling, and if field parameters confirm that formation water — not casing water — is being collected.

Well purging
Low-flow purging (0.1–0.5 L/min) until pH, conductivity, dissolved oxygen, Eh, turbidity and temperature stabilise — typically 3–5 well volumes. Purge records maintained for QA/QC.
Field parameters
Continuous measurement of pH, conductivity (µS/cm), dissolved oxygen (mg/L), oxidation-reduction potential (mV), turbidity (NTU) and temperature (°C) throughout purging. Stability criteria: <10% variation over 3 consecutive readings.
Sample collection
Samples collected through dedicated low-flow pump or bailer after stabilisation. Transferred directly to laboratory-prepared containers — pre-acidified for metals, preserved with HCl/Na₂S₂O₃ for VOCs. No headspace in VOC containers.
Chain of custody
Temperature-controlled sample transport (4°C), documented chain of custody from well to laboratory, preservation verification on arrival, laboratory receipt confirmation.
Drinking water analysis — potability assessment
Complete potability panels for supply wells, production wells and water supply systems
Argentine CAA Resolution 494/94 (SMR-Q) · WHO Guidelines (2022) · EPA MCLs
⚗️ Physicochemical
pH · conductivity · turbidity · colour · odour · taste · total dissolved solids (TDS) · hardness (total, Ca, Mg) · alkalinity · acidity · dissolved oxygen · redox potential · iron (total, dissolved) · manganese · silica
💊 Macro-ions and nutrients
Chlorides · sulphates · nitrates (NO₃⁻) · nitrites (NO₂⁻) · ammonium (NH₄⁺) · phosphates · fluorides · bromides · sodium · potassium · calcium · magnesium · bicarbonates · carbonates · SAR index
☠️ Trace metals and metalloids
Arsenic (As) · Antimony (Sb) · Barium (Ba) · Cadmium (Cd) · Chromium total · Cr(VI) · Lead (Pb) · Mercury (Hg) · Nickel (Ni) · Selenium (Se) · Zinc (Zn) · Copper (Cu) · Iron · Manganese · by ICP-MS at µg/L (ppb) levels
Glyphosate and AMPA — the priority herbicide in Argentine groundwater
Glyphosate and AMPA analysis by HPLC-MS/MS — the analytical challenge solved
Sub-ppb detection limits · HPLC-MS/MS · derivatisation protocol · water matrix · Argentine and WHO guideline comparison
Why glyphosate is the critical herbicide in Argentine groundwater
Argentina is the world's third-largest user of glyphosate — applied intensively across soybean, maize and sunflower crops in the Pampa region. Glyphosate is polar, water-soluble and resistant to hydrolysis, giving it significant mobility in the soil-water system. AMPA (aminomethylphosphonic acid) is the primary degradation product and is equally regulated.

Despite its widespread use, glyphosate analysis in water is technically demanding — its highly polar, ionic character makes it poorly retained on standard reversed-phase HPLC columns, and it requires either derivatisation (FMOC-Cl) or HILIC/ion-pair chromatography for reliable quantification.
Biogroup's analytical approach
✓ Method: HPLC-MS/MS with FMOC-Cl derivatisation or direct LC-MS/MS (HILIC column)
✓ Detection limit: 0.05 µg/L (0.05 ppb) — below all applicable regulatory thresholds
✓ Analytes: Glyphosate + AMPA (metabolite) reported individually
✓ Argentine guideline: 0.9 mg/L (CAA Resolution 494/94) — note that this limit predates modern risk assessments
✓ WHO guideline: 1 mg/L
✓ EU limit (drinking water): 0.1 µg/L (individual pesticide)
✓ Full pesticide multi-residue panel also available (100+ compounds)
Biogroup also analyses the full organophosphate and organochlorine pesticide panels in groundwater — atrazine, acetochlor, endosulfan, chlorpyrifos and 80+ additional compounds by GC-MS and HPLC-MS/MS.
Contaminated site groundwater analysis — Table 2 Decree 831/93 full panel
Complete Decree 831/93 Table 2 analytical capability — groundwater quality guidelines
Full contaminant panel · EPA SW-846 methods · GC-MS · ICP-MS · HPLC-MS/MS · results reported vs. Table 2 thresholds

For contaminated site investigations (Phase II ESA), remediation monitoring and regulatory submissions, Biogroup provides the complete groundwater contaminant panel with results compared against Decree 831/93 Table 2 groundwater quality guidelines — the Argentine regulatory reference for contaminated site decisions.

TPH fractions
GRO · DRO · MRO · TX-1005/1006 · GC-FID
BTEX
Benzene · toluene · ethylbenzene · xylenes · GC-MS purge-and-trap
MTBE / TAME
Fuel oxygenates · GC-MS headspace · Table 2
VOCs & SVOCs
EPA 8260B · EPA 8270D · 60+ compounds
PAHs
16 EPA priority · HPLC-FLD · benzo(a)pyrene
Chlorinated solvents
TCE · PCE · DCE · VC · GC-MS · EPA 8260
Heavy metals
ICP-MS · As/Cd/Cr/Pb/Hg/Ni/Zn · EPA 3005A
Cr(VI)
Hexavalent chromium · colorimetric/IC · EPA 3060A
Pesticides
OC · OP · glyphosate · HPLC-MS/MS · GC-MS
PCBs
GC-ECD · EPA 8082A · Aroclor series
Cyanides
Free + total · colorimetric · IC
Inorganic anions
Nitrates · sulphates · chlorides · fluorides · IC
Long-term aquifer monitoring network management
📊 Periodic monitoring campaigns
Scheduled monitoring campaigns (monthly, quarterly, semi-annual or annual) with synchronous level measurement and groundwater sampling across all network wells. Required for: contaminated site remediation monitoring, landfill environmental surveillance, industrial facility groundwater compliance and regulatory reporting.
✓ Full level-and-sample campaign per monitoring round
✓ Trend analysis — contaminant concentration vs. time
✓ Water table contouring each round
✓ Comparison against previous rounds
✓ Exceedance flag and regulatory reporting
📋 Monitoring reports
Each monitoring campaign produces a complete report submitted to the site owner and, where required, to regulatory authorities — documenting levels, analytical results, trend analysis, exceedances and recommendations.
✓ Piezometric level table and water table map
✓ Full analytical results with laboratory certificates
✓ Comparison against Table 2 / Table 9 screening levels
✓ Concentration trend plots for each analyte and well
✓ Plume extent assessment
✓ Remediation system performance evaluation (if applicable)
Applications — when underground water monitoring is required
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Petrol stations & fuel spills
BTEX, MTBE and TPH in shallow aquifer. Plume monitoring during active remediation. Required for Phase II characterisation and closure certification.
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Agricultural zones
Nitrates, glyphosate, AMPA and pesticide residues in phreatic aquifer. Drinking water quality of private production wells.
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Landfills
Leachate plume impact assessment on downgradient groundwater. Regulatory monitoring network per Ley 24.051 and provincial waste facility requirements.
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Industrial facilities
Baseline groundwater quality and ongoing compliance monitoring. Phase II investigation support — sampling, analysis and plume characterisation.
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Potability of supply wells
Physicochemical and microbiological potability panels for private and municipal supply wells, swimming pools and industrial process water.
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Construction & development
Pre-construction groundwater baseline. Dewatering water quality monitoring. Assessment of groundwater impact from construction activities.
Regulatory framework — groundwater quality standards
🇦🇷 Argentine standards
• Decree 831/93 Table 2 — groundwater quality guidelines
• Decree 831/93 Table 9 — soil guideline values (cross-ref)
• CAA Res. 494/94 (SMR-Q) — drinking water standard
• Ley 24.051 — hazardous waste / groundwater protection
• ENOHSA / ERAS — drinking water regulatory framework
• Provincial — Santa Fe · Buenos Aires · Córdoba regulations
🌍 WHO Guidelines
• WHO Guidelines for Drinking Water Quality (4th ed. 2022)
• Arsenic: 10 µg/L · Nitrates: 50 mg/L
• Glyphosate: 1 mg/L (provisional)
• Fluoride: 1.5 mg/L
• Cryptosporidium / Giardia: treatment targets
• E. coli: absent in 100 mL
🇺🇸 EPA standards
• EPA MCLs — Maximum Contaminant Levels (40 CFR Part 141)
• EPA RSLs — Regional Screening Levels (groundwater)
• Arsenic: 10 µg/L · Lead: 15 µg/L (action level)
• Benzene: 5 µg/L · TCE: 5 µg/L
• MTBE: 20 µg/L (secondary, taste/odour)
• SW-846 — analytical methods for groundwater
Related services
Monitoring Wells · Aquifer Sampling · Glyphosate · Potability · Table 2
Need groundwater monitoring or analysis?
From potability testing of a supply well to a full contaminated site monitoring network — Biogroup provides well construction, representative sampling and complete analytical characterisation in one integrated service.
Request a groundwater study →
📞 +54 341 425-6431 📞 +54 341 447-4486 ✉ biogroup@biogroup.com.ar 📍 3 de febrero 920 · Rosario, Argentina Mon–Fri 08:00–17:00