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Key Facts: Engineer Soil Environment Exam

80 items

Official written exam paper length (4 subjects × 20)

Q-Net Engineer-grade testing standards; Q-Net 토양환경기사 (jmCd 1669)

120 minutes

Written examination duration (30 minutes per subject)

Q-Net 필기시험 접수안내 (기사·산업기사 과목별 30분)

40 / 60

Passing standard: 40% individual subject floor (과락) and 60% overall average

National Technical Qualifications Act Enforcement Rules

KRW 19,400

Written exam registration fee

Q-Net 토양환경기사 page, checked 2026-09-21

KRW 22,600

Practical exam registration fee

Q-Net 토양환경기사 page, checked 2026-09-21

2 years

Exemption duration for written test pass

National Technical Qualifications Act Enforcement Decree Article 21

토양환경기사 is South Korea's benchmark Engineer-grade soil and groundwater qualification (jmCd 1669, Ministry of Environment / HRD Korea). The official written exam comprises 80 MCQs across four subjects (20 per subject, 30 min each, 120 min total) requiring a 40% per-subject floor (과락) and 60% overall average, followed by a 2.5-hour descriptive practical exam (필답형) in soil environmental practice (토양환경실무). Official Q-Net fees are KRW 19,400 (written) and KRW 22,600 (practical). OpenExamPrep provides an independent 100-question English MCQ practice bank adapted for rigorous bilingual study.

Sample Engineer Soil Environment Practice Questions

Try these sample questions to review concepts for the Engineer Soil Environment exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a natural soil profile (토양단면), which master horizon is characterized primarily by the loss and eluviation (용탈작용) of silicate clay, iron, aluminum, or organic matter, leaving a concentration of resistant quartz and other sand/silt-sized mineral grains?

A.E horizon (용탈층)

B.O horizon (유기물층)

C.B horizon (집적층)

D.C horizon (모재층)

Explanation: The E horizon (eluvial layer, 용탈층) is a mineral horizon located below the A horizon and above the B horizon that has undergone significant eluviation of silicate clay, iron, aluminum, and humus, resulting in a bleached, light-colored layer dominated by resistant quartz particles.

2An undisturbed sandy loam core sample has a measured total porosity (공극률 n) of 0.40 (40%). What is the void ratio (간극비 e) of this soil specimen?

A.0.40

B.0.67

C.0.80

D.1.50

Explanation: The mathematical relationship converting porosity (n) to void ratio (e) is e = n / (1 - n). Substituting n = 0.40 yields e = 0.40 / (1 - 0.40) = 0.40 / 0.60 = 2/3 ≈ 0.67.

3According to the United States Department of Agriculture (USDA) particle-size classification standard, what is the defined equivalent spherical diameter range for silt (미사 / 실트)?

A.< 0.002 mm

B.0.05 mm to 2.0 mm

C.0.002 mm to 0.05 mm

D.0.02 mm to 0.2 mm

Explanation: Under the USDA classification system: clay (점토) is < 0.002 mm, silt (미사) ranges from 0.002 mm to 0.05 mm, and sand (모래) ranges from 0.05 mm to 2.0 mm. Under the ISSS (International) system, silt is defined as 0.002 mm to 0.02 mm.

4A dissolved organic contaminant migrates through a sandy aquifer with a dry bulk density (건조밀도) ρ_b = 1.50 g/cm³ and an effective porosity (유효공극률) n_e = 0.25. If the linear distribution coefficient (분배계수) K_d for the contaminant is 0.50 mL/g, what is the retardation factor (지체계수 R)?

A.2.0

B.2.5

C.3.0

D.4.0

Explanation: The retardation factor R in porous media solute transport is defined by R = 1 + (ρ_b / n_e) * K_d. Substituting the given parameters: R = 1 + (1.50 / 0.25) * 0.50 = 1 + 6.0 * 0.50 = 1 + 3.0 = 4.0. This means the dissolved plume moves at 1/4 the speed of advective groundwater seepage.

5In soil physics, soil water potential is frequently expressed as a pF value (pF = log₁₀ h, where h is matric suction head in cm H₂O). What is the standard pF value corresponding to field capacity (포장용수량)?

A.pF 2.5 to 2.7

B.pF 0

C.pF 4.2

D.pF 7.0

Explanation: Field capacity (포장용수량) corresponds to the water content remaining in soil after gravitational water has drained away (typically 1 to 3 days after saturated wetting), which occurs at a matric suction of roughly 1/3 bar (33 kPa or ~330 to 500 cm H₂O), equivalent to pF 2.5 to 2.7.

6Which clay mineral is a non-expanding 1:1 layer phyllosilicate composed of one silicon tetrahedral sheet and one aluminum octahedral sheet bonded tightly by interlayer hydrogen bonds, characterized by minimal swelling and low cation exchange capacity (CEC 3–15 cmol(+)/kg)?

A.Montmorillonite (몬모릴로나이트)

B.Kaolinite (카올리나이트)

C.Illite (일라이트)

D.Vermiculite (버미큘라이트)

Explanation: Kaolinite is the textbook 1:1 clay mineral consisting of alternating silica tetrahedral and alumina octahedral sheets. The basal oxygen atoms of the tetrahedral sheet form strong hydrogen bonds with hydroxyl groups of the adjacent octahedral sheet, preventing water molecules and hydrated cations from entering the interlayer space, leading to low CEC (3–15 cmol(+)/kg) and no shrink-swell behavior.

7Groundwater flows through a confined aquifer over a 500 m distance where the piezometric head drops from 42.0 m to 37.0 m. If the hydraulic conductivity is K = 2.5 × 10⁻⁴ m/s and the effective porosity is n_e = 0.20, what is the actual seepage velocity (실제 침투유속 v_s)?

A.2.5 × 10⁻⁶ m/s

B.5.0 × 10⁻⁶ m/s

C.1.25 × 10⁻⁵ m/s

D.2.5 × 10⁻⁵ m/s

Explanation: First, calculate the hydraulic gradient: i = Δh / L = (42.0 - 37.0) / 500 = 5.0 / 500 = 0.010. Next, calculate Darcy flux: v = K * i = (2.5 × 10⁻⁴ m/s) * 0.010 = 2.5 × 10⁻⁶ m/s. Finally, the actual seepage velocity through interconnected pore channels is v_s = v / n_e = (2.5 × 10⁻⁶ m/s) / 0.20 = 1.25 × 10⁻⁵ m/s.

8According to the lyotropic series (호액계열 / 양이온 흡착세기 순서) for soil colloidal surfaces, which cation exhibits the strongest electrostatic adsorption affinity and greatest replacing power under neutral to slightly acidic conditions?

A.Na⁺

B.K⁺

C.Mg²⁺

D.Al³⁺

Explanation: The lyotropic series of cation adsorption affinity on negative soil colloid surfaces is determined by valence and hydrated ionic radius: Al³⁺ > Ca²⁺ > Mg²⁺ > K⁺ ≈ NH₄⁺ > Na⁺. Polyvalent cations with higher charge and smaller hydrated radii are held most tightly.

9An undisturbed cylinder soil core has an inner volume of 100 cm³ and an oven-dry solid mass of 132.5 g. Assuming a standard soil particle density (진비중 ρ_s) of 2.65 g/cm³, what is the total porosity (공극률 n) of the soil?

A.50.0%

B.35.0%

C.40.0%

D.65.0%

Explanation: Bulk density ρ_b = mass / total volume = 132.5 g / 100 cm³ = 1.325 g/cm³. Total porosity is calculated as n = [1 - (ρ_b / ρ_s)] * 100% = [1 - (1.325 / 2.65)] * 100% = [1 - 0.50] * 100% = 50.0%.

10What is the principal mechanism responsible for generating permanent, pH-independent negative electrical charges in 2:1 smectite and vermiculite clay minerals?

A.Deprotonation of surface carboxyl and phenolic hydroxyl groups

B.Isomorphous substitution of lower-valence cations in crystal lattice sheets

C.Protonation of edge broken-bond aluminum hydroxyl groups

D.Hydrolysis of soluble aluminum sulfate complexes

Explanation: Permanent (constant) negative charges arise from isomorphous substitution (동형치환) during mineral crystallization, where lower-valence cations substitute for higher-valence cations of similar ionic radius without altering the crystal structure (e.g., Al³⁺ substituting for Si⁴⁺ in tetrahedral sheets, or Mg²⁺/Fe²⁺ substituting for Al³⁺ in octahedral sheets).

About the Engineer Soil Environment Exam

Engineer Soil Environment (토양환경기사, jmCd 1669) is South Korea's premier Engineer-grade national technical qualification in subsurface environmental engineering, administered by the Human Resources Development Service of Korea (HRD Korea / Q-Net) under the Ministry of Environment (환경부). The written examination evaluates 80 four-option multiple-choice questions across four foundational subjects: Soil and Groundwater Characteristics (토양 및 지하수 특성), Soil and Groundwater Investigation and Assessment (토양 및 지하수 조사·평가), Soil and Groundwater Remediation Technology (토양 및 지하수 정화기술), and Environmental Regulations (토양 및 지하수 환경관계법규). Candidates passing the written paper advance to a 2.5-hour descriptive practical examination (필답형) covering remediation system sizing, investigative data interpretation, and regulatory compliance (토양환경실무). OpenExamPrep provides an independent English-language MCQ study adaptation designed for mastery of core subsurface engineering principles, mathematical problem solving, and Korean environmental terminology.

Exam sponsor: HRD Korea (Q-Net) / Ministry of Environment (환경부). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written paper covering 토양 및 지하수 특성 (Soil & Groundwater Characteristics), 토양 및 지하수 조사·평가 (Investigation & Assessment), 토양 및 지하수 정화기술 (Remediation Technology), and 토양 및 지하수 환경관계법규 (Environmental Regulations) with 20 items and 30 minutes each (80 items / 120 minutes total), followed by a 2.5-hour, 100-point written-answer practical examination in 토양환경실무. OpenExamPrep study weights cover all four written subjects.

Time Limit

120 minutes for the four written subjects (30 minutes each); practical: 3 hours written-answer

Passing Score

Written: 40+ per subject (과락 floor) and 60 average; practical: 60/100

Exam / Certification Fees

KRW 19,400 written / KRW 22,600 practical (Q-Net, 2026-09-21)

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Q-Net Engineer Soil Environment (토양환경기사) exam page (jmCd=1669) · Source checked 2026-09-21Official Korean/English qualification details, Ministry of Environment, HRD Korea, 2026 examination schedule, written/practical fees KRW 19,400 / 22,600, and current 출제기준 qualification specifications.
Q-Net national technical qualification grading method (Engineer grade) · Source checked 2026-09-21Written: four-option MCQ, 20 items per subject, 40 per subject floor (과락) and 60 overall average. Practical: 60/100.
Q-Net written-exam timing (기사·산업기사 과목별 30분) · Source checked 2026-09-21Total 120 minutes for 4 subjects (30 minutes per subject).
National Technical Qualifications Act Enforcement Decree — 2-year written-pass exemption · Source checked 2026-09-21Article 21 provides a two-year exemption from the written exam for candidates who pass the written paper.
Ministry of Environment — Soil Environment Conservation Act · Source checked 2026-09-21Statutory foundation for soil contamination concern/countermeasure standards, remediation orders, and specialized agency certifications.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

25%

Soil and Groundwater Characteristics (토양 및 지하수 특성)

Master soil profile horizons (O, A, E, B, C, R), USDA textural classification, soil phase relationships (void ratio, porosity, dry bulk density, volumetric moisture content), soil water potential and pF retention curves, clay mineral crystallography (1:1 kaolinite vs 2:1 smectite/illite/vermiculite), isomorphous substitution, cation exchange capacity (CEC) lyotropic series, base saturation, humic substances (humic acid, fulvic acid, humin), soil redox sequence, and hydrogeology (Darcy's law groundwater flux, seepage velocity, transmissivity, storativity, hydrodynamic dispersion, and retardation factor R).

25%

Investigation and Assessment (토양 및 지하수 조사·평가)

Covers Phase I non-intrusive historical site assessments and Phase II intrusive detailed investigations, systematic grid sampling patterns, mandatory discrete zero-headspace sampling for VOCs versus composite sampling for metals/TPH, drilling technologies (Hollow Stem Auger vs Direct Push Geoprobe), groundwater monitoring well construction (filter pack, bentonite seal, screen placement for LNAPL vs DNAPL), low-flow purging stabilization criteria, Korean Standard Test Methods (aqua regia digestion for heavy metals, GC-FID with silica gel cleanup for TPH, Headspace GC-FID for BTEX, diphenylcarbazide spectrophotometry for Cr6+, CVAAS for mercury, HG-AAS for arsenic), QA/QC protocols (RPD, MDL, trip blanks), and human health risk assessment (Hazard Quotient HQ, Excess Lifetime Cancer Risk ELCR).

25%

Remediation Technology (토양 및 지하수 정화기술)

Comprehensive engineering design of in-situ technologies (Soil Vapor Extraction SVE radius of influence and well network sizing, bioventing oxygen delivery, air sparging coupled with SVE, In-Situ Chemical Oxidation ISCO with Fenton's reagent, potassium permanganate, and activated persulfate, Zero-Valent Iron ZVI permeable reactive barriers PRB, phytoremediation mechanisms including phytoextraction, phytostabilization, and rhizofiltration, electrokinetic remediation electroosmotic flow in clays, Multi-Phase Extraction MPE/DPE, Monitored Natural Attenuation MNA geochemical footprints, and Enhanced Reductive Dechlorination ERD bioaugmentation with Dehalococcoides) and ex-situ systems (soil washing grain size cutoff and mass balances, low- vs high-temperature thermal desorption, landfarming tilling and C:N:P nutrient ratios, biopiles, slurry-phase bioreactors, cementitious solidification/stabilization S/S, vitrification, and pump-and-treat rebounding mechanisms).

25%

Environmental Regulations (토양 및 지하수 환경관계법규)

In-depth coverage of the Soil Environment Conservation Act (토양환경보전법: statutory definitions of soil contaminants, Specific Soil Contamination Control Facilities 20,000 L thresholds, land-use classifications for Region 1, 2, and 3, numerical Soil Contamination Concern Standards and Countermeasure Standards, regular and leakage inspection cycles for underground petroleum tanks, Countermeasure Area designation by the Minister of Environment or Mayor/Do Governor, administrative remediation orders and statutory compliance extensions up to 4 years, strict prohibition of off-site soil transport and statutory exceptions, Soil Purifying Business registration requirements, independent verification by Soil Specialized Agencies, strict polluter liability without fault, and innocent purchaser defenses through voluntary soil environmental assessments) and the Groundwater Act (지하수법: designated use categories, drinking water quality standards, development permit vs report thresholds, abandoned well bottom-to-top pressure grouting decommissioning, Groundwater Conservation Areas, and the National Groundwater Monitoring Network).

Preparing for the Engineer Soil Environment Exam

What You Need to Know

Passing score: Written: 40+ per subject (과락 floor) and 60 average; practical: 60/100
Assessment: Written paper covering 토양 및 지하수 특성 (Soil & Groundwater Characteristics), 토양 및 지하수 조사·평가 (Investigation & Assessment), 토양 및 지하수 정화기술 (Remediation Technology), and 토양 및 지하수 환경관계법규 (Environmental Regulations) with 20 items and 30 minutes each (80 items / 120 minutes total), followed by a 2.5-hour, 100-point written-answer practical examination in 토양환경실무. OpenExamPrep study weights cover all four written subjects.
Time limit: 120 minutes for the four written subjects (30 minutes each); practical: 3 hours written-answer
Exam / certification fees: KRW 19,400 written / KRW 22,600 practical (Q-Net, 2026-09-21) Official sources

Using Our Practice Resources

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Engineer Soil Environment: Suggested Study Strategy

1Master quantitative calculations early: Problems involving Darcy's law flux (Q = K·i·A), seepage velocity (v_s = v/n_e), retardation factor (R = 1 + (ρ_b/n)·K_d), SVE radius of influence well counts, stoichiometric oxidant demand, and soil washing mass balances appear frequently on both the written exam and practical paper.

2Guard against the 40% subject floor (과락) in Environmental Regulations: Memorize the exact numerical Soil Contamination Concern Standards (Table 3) for Region 1, 2, and 3 (specifically for Cd, Pb, As, Hg, Cr6+, TPH, and Benzene) and statutory time limits (2-year remediation order, max 2-year extension, 10-year tank leakage inspection).

3Understand the mechanics of soil remediation technologies: Distinguish carefully between in-situ SVE (high airflow, vadose zone, physical volatilization) and bioventing (low airflow, oxygen delivery for biodegradation), as well as Fenton's reagent (acidic pH 3–5, •OH) versus permanganate (alkenes, broad pH) and persulfate (SO4•-).

4Pair Korean technical terms with standard environmental engineering concepts: Terms like 양이온교환용량 (CEC), 투수계수 (hydraulic conductivity), 공극률 (porosity), 간극비 (void ratio), 토양오염우려기준 (concern standards), 토양오염대책기준 (countermeasure standards), 특정토양오염관리대상시설 (specific control facilities), and 반출정화 (off-site remediation) are central to succeeding on the exam.

Frequently Asked Questions

What is the official structure of the Engineer Soil Environment (토양환경기사) examination?

The official qualification examination consists of two consecutive stages administered by HRD Korea (Q-Net). Stage 1 is a 120-minute written examination (필기시험) consisting of 80 four-option multiple-choice questions (20 questions across four subjects: 토양 및 지하수 특성, 토양 및 지하수 조사·평가, 토양 및 지하수 정화기술, and 토양 및 지하수 환경관계법규). Stage 2 is a 2.5-hour written-answer descriptive practical examination (실기시험 필답형) in Soil Environmental Practice (토양환경실무), worth 100 points.

What are the passing criteria and the 'gwarak' (과락) disqualification rule?

To pass the written examination, candidates must achieve an overall average score of at least 60% (48 out of 80 questions correct across all four subjects) AND obtain at least 40% in every individual subject (at least 8 out of 20 questions correct per subject). Scoring below 40% (fewer than 8 correct) in any single subject constitutes an automatic disqualification ('gwarak', 과락), regardless of the total score. The practical examination requires a score of 60 points or higher out of 100.

What are the official exam registration fees and where do candidates register?

As published on Q-Net (jmCd 1669, verified for 2026), the written exam registration fee is KRW 19,400, and the practical exam fee is KRW 22,600. Registration is conducted online through the official HRD Korea portal (q-net.or.kr) during designated national testing windows.

How long is a written exam pass valid for attempting the practical exam?

Under Article 21 of the Enforcement Decree of the National Technical Qualifications Act (국가기술자격법 시행령 제21조), candidates who pass the written examination are granted an exemption from the written test for exactly 2 years from the date of the written pass announcement, during which they can challenge the practical examination.

What is OpenExamPrep's relationship to the official Q-Net examination?

OpenExamPrep provides an independent English-language MCQ practice bank covering core technical topics, engineering calculation problems, and Korean regulatory terminology. It is not affiliated with or endorsed by HRD Korea or the Ministry of Environment. The official national exam is administered in Korean on Q-Net, and this resource serves as an independent preparatory tool for international students, bilingual professionals, and candidates seeking conceptual mastery.