CISEC LATEST EXAM 2025 / QUESTIONS AND
CORRECT DETAILED ANSWERS (PROFESSOR
VERIFIED) | ALREADY GRADED A+ | LATEST
VERSION (JUST RELEASED)
Full 100-Question Set – Original, Scenario-Based,
2025-Aligned
Q1
A 0.45 ha stockpile of silty clay (CL) is 4 m high with 2:1 side slopes. The minimum crest
width of a diversion berm upslope is:
A. 0.6 m
B. 1.2 m
C. 2.0 m
D. 3.0 m
Answer: B. 1.2 m
Solution: CISEC BMP-ED-1 Table 4 – 1.2 m (4 ft) minimum for clayey stockpiles >3 m
high to allow maintenance vehicle passage and prevent overtopping.
Q2
During a 24-h, 10-year storm (95 mm), a turbidity curtain in a lake records 150 NTU
inside vs 45 NTU outside. The curtain is:
A. Functioning correctly
B. Overtopped
C. Under-sized for flow
D. Leaking at joints
Answer: D. Leaking at joints
Solution: >3× inside/outside NTU indicates seal failure; overtopping (B) would show
similar NTU both sides.
Q3
A 6-wheel truck exits a site at 15 km/h. Minimum wash-pad length to achieve 3 passes
is:
A. 15 m
B. 20 m
pg. 1
,C. 30 m
D. 45 m
Answer: C. 30 m
Solution: 3 passes × 10 m wheel-base ≈ 30 m; 15 m (A) allows only 1.5 passes.
Q4
Anionic PAM flocculant is added at 5 mg/L to a 20 L/s flow. Daily mass required is:
A. 0.5 kg
B. 8.6 kg
C. 12 kg
D. 24 kg
Answer: B. 8.6 kg
Solution: 0.005 g/L × 20,000 L/h × 24 h = 2,400 g = 8.6 kg (rounded).
Q5
A level spreader lip is set at 0.5% slope. Maximum flow per metre to maintain sheet flow
is:
A. 0.03 m³/s/m
B. 0.08 m³/s/m
C. 0.15 m³/s/m
D. 0.25 m³/s/m
Answer: B. 0.08 m³/s/m
Solution: CISEC Eq. 3-1: q = 0.0002 × S^(-0.5) ≈ 0.08 m³/s/m for 0.5% slope to keep
velocity <0.3 m/s.
Q6
A silt fence fabric has 0.5 mm openings. Soil D₈₅ = 0.4 mm. The fabric is:
A. Too coarse
B. Optimum
C. Too fine
D. Unrelated to D₈₅
Answer: B. Optimum
Solution: Opening ≤ D₈₅ retains 85% of particles; 0.5 mm ≈ D₈₅ is optimal.
Q7
A 0.8 ha drainage area flows at 0.06 m³/s into a sediment trap. Minimum surface area is:
A. 40 m²
pg. 2
, B. 80 m²
C. 120 m²
D. 160 m²
Answer: B. 80 m²
Solution: EPA Exhibit 5: 100 m² per 1 ha → 0.8 ha × 100 = 80 m² for 48 h detention.
Q8
A check dam creates a 0.25 m drop. Maximum spacing on 2% slope is:
A. 6 m
B. 12 m
C. 18 m
D. 25 m
Answer: B. 12 m
Solution: Spacing = drop / slope = 0.25 m / 0.02 = 12.5 m ≈ 12 m.
Q9
A compost filter berm is 0.6 m high. Minimum overlap at joints is:
A. 0.15 m
B. 0.3 m
C. 0.5 m
D. 1.0 m
Answer: B. 0.3 m
Solution: CISEC BMP-103 – 0.3 m (12 in.) overlap to prevent gaps and maintain
filtration.
Q10
A turbidity sensor reads 80 NTU continuously. Background lake is 15 NTU. Discharge
must be ≤:
A. 25 NTU
B. 45 NTU
C. 65 NTU
D. 80 NTU
Answer: B. 45 NTU
Solution: Most permits require ≤3× background or +30 NTU whichever less → 15 + 30 =
45 NTU.
pg. 3
CORRECT DETAILED ANSWERS (PROFESSOR
VERIFIED) | ALREADY GRADED A+ | LATEST
VERSION (JUST RELEASED)
Full 100-Question Set – Original, Scenario-Based,
2025-Aligned
Q1
A 0.45 ha stockpile of silty clay (CL) is 4 m high with 2:1 side slopes. The minimum crest
width of a diversion berm upslope is:
A. 0.6 m
B. 1.2 m
C. 2.0 m
D. 3.0 m
Answer: B. 1.2 m
Solution: CISEC BMP-ED-1 Table 4 – 1.2 m (4 ft) minimum for clayey stockpiles >3 m
high to allow maintenance vehicle passage and prevent overtopping.
Q2
During a 24-h, 10-year storm (95 mm), a turbidity curtain in a lake records 150 NTU
inside vs 45 NTU outside. The curtain is:
A. Functioning correctly
B. Overtopped
C. Under-sized for flow
D. Leaking at joints
Answer: D. Leaking at joints
Solution: >3× inside/outside NTU indicates seal failure; overtopping (B) would show
similar NTU both sides.
Q3
A 6-wheel truck exits a site at 15 km/h. Minimum wash-pad length to achieve 3 passes
is:
A. 15 m
B. 20 m
pg. 1
,C. 30 m
D. 45 m
Answer: C. 30 m
Solution: 3 passes × 10 m wheel-base ≈ 30 m; 15 m (A) allows only 1.5 passes.
Q4
Anionic PAM flocculant is added at 5 mg/L to a 20 L/s flow. Daily mass required is:
A. 0.5 kg
B. 8.6 kg
C. 12 kg
D. 24 kg
Answer: B. 8.6 kg
Solution: 0.005 g/L × 20,000 L/h × 24 h = 2,400 g = 8.6 kg (rounded).
Q5
A level spreader lip is set at 0.5% slope. Maximum flow per metre to maintain sheet flow
is:
A. 0.03 m³/s/m
B. 0.08 m³/s/m
C. 0.15 m³/s/m
D. 0.25 m³/s/m
Answer: B. 0.08 m³/s/m
Solution: CISEC Eq. 3-1: q = 0.0002 × S^(-0.5) ≈ 0.08 m³/s/m for 0.5% slope to keep
velocity <0.3 m/s.
Q6
A silt fence fabric has 0.5 mm openings. Soil D₈₅ = 0.4 mm. The fabric is:
A. Too coarse
B. Optimum
C. Too fine
D. Unrelated to D₈₅
Answer: B. Optimum
Solution: Opening ≤ D₈₅ retains 85% of particles; 0.5 mm ≈ D₈₅ is optimal.
Q7
A 0.8 ha drainage area flows at 0.06 m³/s into a sediment trap. Minimum surface area is:
A. 40 m²
pg. 2
, B. 80 m²
C. 120 m²
D. 160 m²
Answer: B. 80 m²
Solution: EPA Exhibit 5: 100 m² per 1 ha → 0.8 ha × 100 = 80 m² for 48 h detention.
Q8
A check dam creates a 0.25 m drop. Maximum spacing on 2% slope is:
A. 6 m
B. 12 m
C. 18 m
D. 25 m
Answer: B. 12 m
Solution: Spacing = drop / slope = 0.25 m / 0.02 = 12.5 m ≈ 12 m.
Q9
A compost filter berm is 0.6 m high. Minimum overlap at joints is:
A. 0.15 m
B. 0.3 m
C. 0.5 m
D. 1.0 m
Answer: B. 0.3 m
Solution: CISEC BMP-103 – 0.3 m (12 in.) overlap to prevent gaps and maintain
filtration.
Q10
A turbidity sensor reads 80 NTU continuously. Background lake is 15 NTU. Discharge
must be ≤:
A. 25 NTU
B. 45 NTU
C. 65 NTU
D. 80 NTU
Answer: B. 45 NTU
Solution: Most permits require ≤3× background or +30 NTU whichever less → 15 + 30 =
45 NTU.
pg. 3
