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Certification Program NGICP ination
Practice Exam
Question 1. Which of the following best defines Green Infrastructure (GI) in the context of stormwater management? A) A network of underground pipes that convey water to treatment plants B) A set of engineered practices that mimic natural hydrologic processes C) A system of concrete channels designed for rapid runoff removal D) A collection of water‑intensive ornamental lawns Answer: B Explanation: GI refers to practices such as bioretention, green roofs, and permeable pavements that restore or imitate natural water cycles, reducing runoff and improving water quality. Question 2. What is the primary difference between green and grey infrastructure? A) Grey infrastructure uses only natural materials, while green uses synthetic ones B) Green infrastructure focuses on water storage, grey on water treatment C) Grey infrastructure relies on engineered conveyance, green on infiltration and evapotranspiration D) Green infrastructure requires more energy to operate Answer: C Explanation: Grey infrastructure typically consists of pipes, culverts, and treatment plants that convey water, whereas green infrastructure emphasizes infiltration, storage, and evapotranspiration.
Certification Program NGICP ination
Practice Exam
Question 3. Which component of the hydrologic cycle is most directly enhanced by a bioretention cell? A) Evaporation from open water bodies B) Sublimation of ice C) Infiltration of stormwater into the soil D) Transpiration from deep‑rooted trees Answer: C Explanation: Bioretention cells are designed to capture runoff and allow it to infiltrate through engineered soil media, increasing infiltration rates. Question 4. Which regulatory driver most commonly mandates the use of GI in new developments in the United States? A) Clean Air Act B) National Pollutant Discharge Elimination System (NPDES) permits C) Endangered Species Act D) Federal Energy Regulatory Commission (FERC) licensing Answer: B Explanation: NPDES permits often include stormwater runoff limits that can be met through GI practices. Question 5. In a site assessment, which soil characteristic is most critical for determining the suitability of a bioretention garden? A pH level
Certification Program NGICP ination
Practice Exam
D) Gravel, filter fabric, engineered soil mix, mulch Answer: D Explanation: The usual sequence is a gravel drainage layer, filter fabric to prevent fine particles from clogging, engineered soil media for plant growth and filtration, and a mulch layer for erosion control. Question 8. Which plant characteristic is most important when selecting species for a rain garden in a temperate climate? A) High nitrogen fixation ability B) Deep root systems for drought tolerance C) Ability to thrive in wet‑dry cyclic conditions D) Evergreen foliage for year‑round aesthetics Answer: C Explanation: Rain garden plants must tolerate alternating saturated and dry periods; species adapted to wet‑dry cycles perform best. Question 9. During construction of a permeable pavement, which step must be completed before placing the surface layer? A) Installing the drainage pipes beneath the slab B) Compacting the subgrade to a minimum of 95% relative density C) Applying a seal coat to the aggregate base D) Planting turf grasses for stabilization
Certification Program NGICP ination
Practice Exam
Answer: B Explanation: Proper subgrade compaction ensures structural stability and prevents differential settlement under the permeable surface. Question 10. In porous asphalt, what is the primary function of the open‑graded aggregate skeleton? A) To provide structural strength only B) To allow water to flow through and be stored in the voids C) To increase the pavement’s friction coefficient D) To bind the asphalt binder more efficiently Answer: B Explanation: The open‑graded aggregate creates interconnected voids that permit water infiltration, reducing surface runoff. Question 11. Which quality‑control test is most commonly used to verify the permeability of a newly installed pervious concrete slab? A) Slump test B) Air‑void analysis C) Falling head permeability test D) Compressive strength test Answer: C Explanation: The falling head test measures the rate at which water passes through the slab, directly assessing permeability.
Certification Program NGICP ination
Practice Exam
A) A thick layer of compacted soil B) A geocomposite with channels for water flow C) A waterproof membrane only D) A layer of sand and gravel Answer: B Explanation: Geocomposites with built‑in flow paths provide drainage while supporting the growing media. Question 15. Which of the following is a critical structural consideration before installing a vegetated (green) roof? A) The roof’s fire rating B) The roof’s load‑bearing capacity, including dead and live loads C) The roof’s color temperature D) The roof’s acoustic insulation value Answer: B Explanation: Green roofs add significant weight; ensuring the roof can support dead (soil, substrate) and live (vegetation, water) loads is essential. Question 16. A blue roof is primarily designed to: A) Provide habitat for water‑fowl B) Store stormwater for delayed release, reducing peak flow C) Generate electricity via hydro turbines
Certification Program NGICP ination
Practice Exam
D) Enhance building aesthetics with reflective water surfaces Answer: B Explanation: Blue roofs detain water on the roof surface and release it slowly, mitigating downstream flooding. Question 17. Which of the following best describes the function of a dry well? A) To provide surface water storage for irrigation B) To act as a subsurface infiltration chamber for stormwater C) To filter pollutants using a sand media filter D) To serve as a decorative water feature Answer: B Explanation: Dry wells receive stormwater and allow it to infiltrate into the surrounding soil, reducing runoff. Question 18. Constructed stormwater wetlands treat runoff primarily through: A) Mechanical filtration using mesh screens B) Biological uptake, sedimentation, and microbial processes C) Chemical oxidation with chlorine D) Evaporation via high‑temperature heating Answer: B
Certification Program NGICP ination
Practice Exam
Question 21. Before any excavation, the “Call 811” rule is intended to: A) Notify the local fire department of construction activities B) Locate underground utilities to prevent accidental strikes C) Register the project with the state environmental agency D) Obtain a building permit from the municipality Answer: B Explanation: Dialing 811 initiates a utility locate service, reducing the risk of damaging buried lines. Question 22. During post‑construction inspection of a bioretention area, a persistent ponded water condition indicates: A) Excessive vegetation growth B) Under‑drain clogging or insufficient infiltration capacity C) Over‑watering of plants D) Improper mulch depth Answer: B Explanation: Ponding suggests water cannot infiltrate or be drained, often due to clogged under‑drains or compacted media. Question 23. Which routine maintenance task is essential for permeable pavement longevity? A) Annual repainting of surface markings
Certification Program NGICP ination
Practice Exam
B) Monthly vacuum sweeping to remove sediment C) Weekly application of sealant coating D) Daily mowing of surrounding grass Answer: B Explanation: Vacuum sweeping removes fine sediments that can clog pores, maintaining infiltration capacity. Question 24. In rainwater harvesting, the “first‑flush” device is used to: A) Divert the initial runoff that may contain higher pollutant loads away from the storage tank B) Accelerate water flow into the tank during low‑intensity storms C) Heat the water to prevent freezing D) Provide a pressure boost for irrigation Answer: A Explanation: The first‑flush captures the initial, often more contaminated runoff, improving water quality in the storage tank. Question 25. Which of the following is a primary indicator of poor performance in a constructed wetland? A) Clear water exiting the wetland B) Absence of emergent vegetation C) High dissolved oxygen levels in the outflow D) Uniform water depth across the wetland
Certification Program NGICP ination
Practice Exam
Explanation: The filter fabric protects the under‑drain and prevents fine particles from migrating into the drainage layer. Question 28. The “hydraulic conductivity” of a permeable pavement’s aggregate base should be at least: A) 0.001 in/hr B) 0.01 in/hr C) 0.1 in/hr D) 1.0 in/hr Answer: C Explanation: A minimum of 0.1 in/hr is generally required to achieve adequate infiltration rates for pervious surfaces. Question 29. Which of the following is NOT a typical function of a green roof? A) Reducing urban heat island temperatures B) Providing additional structural support for the building C) Managing stormwater through retention and evapotranspiration D) Enhancing biodiversity in urban areas Answer: B Explanation: Green roofs add loads; they do not provide structural support but rather require the existing structure to be capable of bearing extra weight.
Certification Program NGICP ination
Practice Exam
Question 30. In a stormwater management plan, “detention” refers to: A) Permanent storage of water for reuse B) Temporary holding of runoff to release it at a controlled rate C) Immediate conveyance of water to downstream streams D) Evaporation of water from open ponds Answer: B Explanation: Detention facilities capture runoff and slowly release it, attenuating peak flows. Question 31. Which of the following best describes a “combined sewer overflow” (CSO) control measure? A) Installation of a high‑capacity water treatment plant B) Separating sanitary and storm sewers or adding GI to reduce storm inflow C) Using chlorine injection to disinfect combined sewage D) Building a larger detention dam downstream Answer: B Explanation: CSO controls aim to reduce stormwater entering combined sewers, often through sewer separation or GI that captures runoff. Question 32. The primary purpose of a “filter fabric” in a bioretention cell is to: A) Provide a decorative surface B) Prevent fine soil particles from migrating into the drainage layer
Certification Program NGICP ination
Practice Exam
Answer: D Explanation: OSHA requires protective systems (shoring, shielding, or sloping) for trenches deeper than 5 ft to prevent cave‑ins. Question 35. Which maintenance activity directly addresses clogging in a bioswale’s infiltration zone? A) Pruning overgrown shrubs B) Aeration or scarification of the soil surface C) Applying a herbicide to control weeds D) Installing additional decorative stones Answer: B Explanation: Aeration or scarification restores pore space, improving infiltration and reducing clogging. Question 36. The “first‑flush” volume in a rainwater harvesting system is typically designed to capture what proportion of a storm event? A) 5 % B) 10 % C) 25 % D) 50 % Answer: B
Certification Program NGICP ination
Practice Exam
Explanation: A common design captures roughly the first 10 % of runoff, which contains the highest pollutant concentrations. Question 37. In a pervious concrete mix, what is the primary role of the “air‑entraining admixture”? A) To increase compressive strength B) To create microscopic air bubbles that improve freeze‑thaw durability C) To reduce the water‑to‑cement ratio D) To accelerate setting time Answer: B Explanation: Air‑entraining admixtures introduce stable air voids, enhancing resistance to freeze‑thaw cycles without significantly affecting permeability. Question 38. Which of the following is an advantage of using vegetated swales over traditional concrete channels? A) Lower initial construction cost B) Higher flow velocity for rapid conveyance C) Ability to filter pollutants and provide habitat D) No maintenance required Answer: C Explanation: Vegetated swales filter sediments, nutrients, and metals while offering ecological benefits.
Certification Program NGICP ination
Practice Exam
B) To temporarily hold runoff and release it at a controlled rate to reduce peak flow C) To filter pollutants through a sand column D) To provide a recreational pond Answer: B Explanation: Detention basins are designed for temporary storage, attenuating peak discharge. Question 42. In a green roof design, the “root barrier” layer is placed to: A) Prevent plant roots from penetrating the waterproof membrane B) Increase the depth of the growing media C) Provide a decorative surface for rooftop access D) Store excess rainwater Answer: A Explanation: The root barrier protects the waterproofing membrane from root intrusion, preserving roof integrity. Question 43. Which of the following inspection tools is most useful for verifying the depth of a permeable pavement sub‑base during construction? A) Soil moisture probe B) Laser level C) Tape measure with a depth gauge D) Infrared thermometer
Certification Program NGICP ination
Practice Exam
Answer: C Explanation: A tape measure equipped with a depth gauge provides a quick, accurate measurement of sub‑base thickness. Question 44. What is the primary reason for installing edge restraints on a permeable pavement? A) To improve aesthetic appearance B) To prevent lateral movement and support the pavement edges, maintaining design geometry C) To increase water infiltration at the pavement edges D) To provide a mounting surface for signage Answer: B Explanation: Edge restraints keep the pavement from spreading laterally, ensuring structural stability and proper alignment. Question 45. Which of the following best explains why mulch depth should be limited to 2– 3 inches in a bioretention cell? A) Excessive mulch reduces infiltration and can cause ponding B) Thicker mulch attracts more wildlife, increasing maintenance C) Shallow mulch promotes faster plant growth D) Mulch depth does not affect performance Answer: A
