S+SNZ Professional Examination — Land Development Engineering Option (New Zealand)

A project earthworks specification prepared under NZS 4431:2022 sets a maximum air-voids ratio of 10%. A compacted-fill test returns 12%. What is the correct conclusion?

• AThe lift fails the project specification and must be addressed before acceptance.
• BThe lift automatically complies because NZS 4431 permits every result up to 15%.
• CThe lift automatically complies because air voids are not a project-specific acceptance c…
• DThe result proves the fill has reached maximum dry density.

Which Scala penetrometer result satisfies the NZS 3604:2011 blow-count criterion used to support a 'good ground' assessment below a proposed footing?

• A>5 blows/100 mm to twice the footing width; >3 deeper; all other clause conditions met.
• BExactly 1 blow per 100 mm at the founding level only.
• CExactly 3 blows per 100 mm for the entire test depth, with no comparison between test sit…
• DAny isolated 10-blow reading, regardless of the weaker layers above or below it.

Which summary correctly states the GD05 minimum storage sizing for sediment retention ponds (SRPs) and decanting earth bunds (DEBs)?

• ASRP: 2% if <18% and <200 m; otherwise 3%. DEB: 2%.
• BSRP: 2% below a 10% slope and 3% at 10% or more; DEB: 0.5%.
• CSRP and DEB: a universal 5% of catchment area.
• DSRP: 0.5%; DEB: no storage requirement.

Which of the following describes the 'bulking factor' of soil and how it affects earthwork volume calculations on a land development site?

• AExcavation increases soil from bank volume to a greater loose volume.
• BThe decrease in volume when soil is compacted in a fill area, resulting in compacted volu…
• CThe expansion of clay soils when moisture is added, measured under saturated conditions.
• DThe reduction in soil volume due to groundwater drawdown during site dewatering.

During a compaction control test under NZS 4402, a fill sample is found to have a relative compaction of 92% of the Maximum Dry Density (MDD). If the project specifications require a minimum of 95% MDD, what directive should the land development engineer issue to the contractor?

• AScarify, condition and re-compact the lift, then re-test it.
• BProceed with the next layer of fill, as a 3% variance is within standard field tolerance.
• CApply a cement stabilization agent to the surface and seal it immediately.
• DIncrease the thickness of the next lift to compensate for the lower density of the curren…

In New Zealand land development, what is the maximum catchment area permitted to drain to a standard Decanting Earth Bund (DEB) under Auckland Council GD05 guidelines?

• A0.3 hectares (3,000m²)
• B1.0 hectare (10,000m²)
• C0.5 hectares (5,000m²)
• D2.0 hectares (20,000m²)

A geotechnical report for a subdivision in clay-rich soils in Northland warns of high 'plasticity index' values. What does a high plasticity index indicate regarding the behavior of the soil?

• AThe soil has a wide range of moisture contents over which it remains plastic, suggesting…
• BThe soil is highly granular and will behave like sand when saturated.
• CThe soil has a high shear strength under dry conditions, meaning it is immune to slope in…
• DThe soil will drain rapidly, preventing the build-up of pore water pressures.

A concept plan shows an unsupported permanent cut batter in cohesive clay. What is the defensible design response?

• ASet the batter from site-specific geotechnical evidence and the adopted council standard
• BUse 1V:1H because cohesive clay is self-supporting once surface vegetation is established
• CUse 1V:2.5H everywhere because NZS 4404 makes that a national maximum slope
• DUse the steepest plant-accessible grade because maintenance access proves stability

When designing a silt fence as part of an erosion and sediment control plan under GD05, what is the minimum required depth of the trench used to key in the geotextile fabric at the base of the fence?

• A200mm
• B50mm
• C100mm
• D500mm

What is the primary function of a 'flocculant treatment system' (such as liquid Alum or Polyaluminum Chloride) applied to a Sediment Retention Pond under New Zealand erosion control standards?

• ATo aggregate fine clay into larger, faster-settling flocs.
• BTo neutralize acidic runoff from exposed subsoil layers before it enters the receiving en…
• CTo inhibit the growth of algae and other biological organisms in the static pond water.
• DTo filter out hydrocarbons and chemical contaminants from earthmoving machinery leaks.

How is the ultimate bearing capacity of a soil related to the 'safe bearing capacity' typically used for designing residential strip footings in New Zealand?

• ASafe bearing capacity is the ultimate bearing capacity divided by a factor of safety (typ…
• BSafe bearing capacity is the ultimate bearing capacity multiplied by a load factor of 1.5.
• CThey are identical under modern Limit State Design codes.
• DSafe bearing capacity only accounts for settlement, whereas ultimate bearing capacity onl…

When checking earthwork compaction on-site, a land development engineer notes that the moisture content of the clay fill is 5% above the Optimum Moisture Content (OMC). What field behavior is expected under these conditions?

• AThe soil will 'sponge' or shear under the weight of the roller, making it impossible to a…
• BThe soil will compact easily with fewer passes of a smooth drum roller.
• CThe soil will behave like dry sand, requiring water trucks to spray the surface.
• DThe soil will contract and form deep surface shrinkage cracks during rolling.

Under NZS 4404:2010, what completion package is required where a geo-professional has been engaged for subdivision earthworks?

• AGeo-professional's GCR plus the NZS 4404 Schedule 2A statement.
• BAn NZS 3910 Practical Completion Certificate.
• CAn RMA Section 223 approval certificate.
• DA works validation report signed by the contractor and earthworks operator.

Which of the following describes the difference between 'compaction' and 'consolidation' in geotechnical engineering?

• ACompaction is the immediate reduction of air voids using mechanical force, while consolid…
• BCompaction is a natural geological process, while consolidation is always artificially in…
• CCompaction applies only to granular soils, while consolidation applies only to bedrock st…
• DCompaction increases the air voids ratio, while consolidation decreases it.

A Scala penetrometer advances 300 mm in four blows. How should that result be used in pavement design?

• ARecord 1.3 blows per 100 mm and use the adopted correlation or direct testing
• BAssign CBR 10 directly because four blows always represents a high-strength pavement subg…
• CAssign CBR 50 directly because the 300 mm penetration depth represents compacted subbase
• DIgnore the result because Scala penetration cannot contribute to a pavement investigation

What is the primary purpose of installing a 'subsoil drain' (novadrain or punched pipe in gravel wrapping) at the toe of an engineered fill batter?

• ATo intercept groundwater seepage, preventing the buildup of pore water pressures that cou…
• BTo collect surface runoff from the batter and channel it directly to the stormwater retic…
• CTo provide a backup conduit for sewer overflows during wet weather events.
• DTo aerate the soil at the base of the slope to encourage grass growth.

When laying out dirty-water diversions on a steep earthworks site under Auckland Council GD05, how should spacing be selected?

• AUse GD05 criteria for slope, contributing area, lining and discharge
• BUse 100 m on every slope because channel capacity is independent of the contributing catc…
• CUse 10 m on every slope because the shortest spacing is always the only compliant solution
• DUse 150 m whenever the discharge enters a sediment-retention device downstream

A land development engineer is calculating the earthworks balance for a site. The excavation volume (cut) is 10,000 bank cubic meters (BCM) of clay. If the soil has a compaction shrinkage factor of 10% when placed in the fill area, what compacted volume of fill will this cut produce?

• A9,000 compacted cubic meters (CCM)
• B11,000 compacted cubic meters (CCM)
• C10,000 compacted cubic meters (CCM)
• D12,000 compacted cubic meters (CCM)

Under NZS 4402, which laboratory test is used to determine the relationship between the moisture content and the dry density of a soil to find the Optimum Moisture Content (OMC)?

• AStandard Proctor test
• BAtterberg Limits Test
• CTriaxial Shear Test
• DHydrometer Sedimentation Test

What is the primary geotechnical risk associated with placing engineered fill directly over an unstripped slope containing organic topsoil and vegetation?

• ACreep and shear failure along the organic interface, leading to slope failure of the fill.
• BAn increase in the optimal moisture content of the fill layer.
• CAccelerated erosion of the surface batter.
• DChemical degradation of the concrete foundations of adjacent buildings.

Using the Rational Method formula, $Q = \frac{C \cdot I \cdot A}{360}$, calculate the peak stormwater runoff flow rate ($Q$) in m³/s for a 2-hectare industrial development site. Assume a runoff coefficient ($C$) of 0.85 and a design rainfall intensity ($I$) of 120 mm/hour.

• A0.567 m³/s
• B2.040 m³/s
• C0.204 m³/s
• D5.667 m³/s

How should a designer establish the self-cleansing criterion for a public stormwater pipeline?

• AApply the authority's cleansing criterion at its specified flow condition
• BAssume 0.3 m/s nationwide because all stormwater networks carry only clear water
• CSet 1.5 m/s as a universal minimum without checking pipe material or the authority standa…
• DUse 3.0 m/s as both the national minimum and maximum for every pipe and gradient

When designing stormwater detention basins in New Zealand, what is the primary hydraulic objective of the basin?

• ATo temporarily store peak flows and release them slowly, limiting post-development peak d…
• BTo store runoff permanently for domestic water supply reuse in the subdivision.
• CTo filter out coarse sand and gravel before the water enters gravity mains.
• DTo recharge the local aquifer by encouraging direct infiltration into the subgrade.

Under Verification Method E1/VM1, when does the 500 mm surface-water freeboard apply to a building floor?

• AFor water at least 100 mm deep extending directly to a road or qualifying car park
• BWhenever a model shows any 1% AEP overland flow anywhere on the same development site
• COnly when a council has adopted NZS 4404 without any local amendment or additional freebo…
• DWhenever finished ground is unpaved, regardless of water depth, flood extent or drainage…

How does the 'Time of Concentration' ($t_c$) affect the peak design flow calculation when using the Rational Method?

• AA shorter concentration time selects higher rainfall intensity and peak flow.
• BA shorter time of concentration decreases the runoff coefficient ($C$), reducing the peak…
• CA longer time of concentration increases the peak flow rate by expanding the catchment ar…
• DTime of concentration is only used to calculate pipe velocities, not flow rates.

Which New Zealand technical publication is most commonly referenced for calculating stormwater runoff volumes and peak flows using a graphical unit hydrograph method (especially in the Auckland region)?

• AAuckland Council TP108
• BNZS 3910 guidelines
• CLINZ Cadastral Survey Rules 2021
• DAustroads Part 3

A territorial authority's adopted project standard limits stormwater manhole spacing to 100 m for pipelines under 1 m diameter. Which proposed spacing is the maximum that complies with that requirement?

• A100 meters
• B50 meters
• C150 meters
• D200 meters

In stormwater pipe design, what hydraulic condition occurs if the actual flow rate ($Q$) exceeds the full-pipe capacity ($Q_{full}$) of the gravity line?

• AThe pipe surcharges, raising the hydraulic grade line and upstream water levels.
• BThe velocity of the water will instantly drop to zero, causing sedimentation.
• CThe pipe material will undergo immediate structural collapse due to vacuums.
• DThe flow will automatically transition to supercritical flow, increasing capacity.

In an NZS 4404-based council standard, what baseline minimum diameter is commonly specified for a public stormwater main rather than a lot connection?

• A300 mm, subject to the council's adopted or amended standard
• B100 mm, because public mains and private house drains have identical access needs
• C150 mm, as a nationwide minimum for every public stormwater main
• D600 mm, because smaller pipes cannot be maintained with modern council equipment

In stormwater hydraulics, what is 'critical flow' and how does it relate to the design of open channels like swales?

• AThe state of flow where the specific energy for a given discharge is at its minimum, corr…
• BThe flow rate at which a swale begins to overflow its banks.
• CThe high-velocity flow that causes immediate scour and erosion of the channel lining.
• DFlow that is highly turbulent and contains suspended sediment.

What is the sound way to allow for climate change when selecting design rainfall for New Zealand stormwater infrastructure?

• AUse current HIRDS data with the council's scenario and design horizon
• BDouble every pre-development peak flow without checking rainfall duration or catchment re…
• CApply one flat 50% uplift to all rainfall depths throughout New Zealand and all design li…
• DReduce the return period by five years so the historical rainfall intensity remains uncha…

When checking a stormwater pipe design using the Manning's equation, what does a higher roughness coefficient ($n$) represent?

• AA rougher internal pipe surface, which increases friction loss and reduces the flow capac…
• BA smoother internal pipe surface, which increases flow velocity.
• CA steeper pipe gradient, which accelerates the flow rate.
• DA larger pipe cross-sectional area, which increases volume.

What is the primary hydraulic risk of designing a stormwater pipeline to operate under supercritical flow conditions ($Fr > 1$)?

• AHigh velocities can cause severe erosion at the outlet and unstable flow transitions (hyd…
• BThe pipe will immediately surcharge and overflow.
• CSilt will deposit rapidly inside the pipe, blocking the flow.
• DThe air inside the pipe will be compressed, causing the joints to blow out.

When the primary stormwater network is exceeded during the territorial authority's adopted major design event, how should the excess runoff be managed?

• AA designed secondary overland path to an approved discharge.
• BBy allowing the water to pond on the road surface indefinitely until it evaporates.
• CBy pumping the excess runoff into the local wastewater network.
• DBy shutting off the intake control valves to prevent water from entering the subdivision.

What controls the minimum grade selected for a 150 mm stormwater connection?

• AThe authority standard plus verified capacity and cleansing performance
• BA nationwide 1-in-200 rule that applies regardless of discharge, pipe type or downstream…
• CThe steepest constructible grade, even if outlet velocity and scour criteria are exceeded
• DA nationwide 1-in-300 rule derived solely from the nominal diameter of the connection

A network owner's adopted standard sets a 150 mm minimum diameter for a public gravity wastewater main serving more than one property. Which diameter is the minimum that complies?

• A150mm
• B100mm
• C225mm
• D300mm

How should Peak Wet Weather Flow be derived for a proposed public wastewater network?

• AUse the wastewater authority's current PWWF design method
• BMultiply ADWF by 1.5 in every network because wet-weather infiltration is nationally unif…
• CMultiply ADWF by 10 in every network so no separate infiltration assessment is needed
• DMultiply ADWF by 1.1 because new pipes can never receive groundwater or storm inflow

Why do adopted wastewater design criteria commonly limit a gravity main to less than full depth at peak design flow?

• ATo retain air space for ventilation and reserve capacity for flow variation and infiltrat…
• BTo reduce the friction loss between the water surface and the pipe soffit.
• CTo ensure that the flow velocity remains completely constant throughout the day.
• DTo allow fish and aquatic life to travel upstream in the pipe network.

Wastewater pump stations must be designed to limit the number of pump starts per hour. What is the primary engineering reason for this constraint?

• AFrequent starting causes electrical and mechanical overheating of the pump motor, leading…
• BFrequent starts cause water hammer in the gravity main downstream.
• CFrequent starting increases the risk of septic conditions in the wet well.
• DCouncils charge a tariff fee for every single pump startup cycle.

What is the correct basis for field pressure testing a newly laid PE100 water main?

• AFollow the approved PE test method and its viscoelastic acceptance calculation
• BUse 500 kPa for every pressure class and accept the main if no bubbles appear above the b…
• CUse gravity head overnight because PE joint integrity cannot be assessed using a pressure…
• DHold every PE main at its nominal pressure class for 24 hours, regardless of design press…

How should a designer establish the firefighting-water requirement for a proposed development under SNZ PAS 4509?

• AClassify the supply, then check its flow, pressure, storage and hydrant criteria
• BAssume every residential or commercial proposal is FW2 and test only the nearest hydrant'…
• CUse a universal 50 L/s at 90 m because building use and sprinkler protection do not affec…
• DUse the normal domestic peak demand because a separate firefighting-water assessment is u…

Which pairing reflects the usual boundary backflow protection for medium- and high-hazard water connections?

• AMedium: testable DCV; high: RPZ device.
• BMedium hazard: RPZ; high hazard: an ordinary swing check valve.
• CMedium and high hazard: an untestable household non-return valve.
• DNo backflow device is needed if the commercial connection has a water meter.

A gravity sewer has less cover than the usual detail beneath a trafficked road. What should the designer do?

• ARaise the road until the sewer has 1.2 m cover, because this is the national minimum
• BCheck owner loading criteria and specifically design any required protection
• CAccept 0.9 m without checking pipe class, wheel load, bedding, groundwater or council req…
• DLower the sewer to 2.0 m because deeper cover always reduces pipe loading and constructio…

A wastewater pump station wet well is being designed. The design flow is $10 \text{ L/s}$, and the pump capacity is $20 \text{ L/s}$. Calculate the minimum required active volume of the wet well to ensure that the pump starts no more than 10 times per hour.

• A1,800 liters (1.8m³)
• B3,600 liters (3.6m³)
• C900 liters (0.9m³)
• D7,200 liters (7.2m³)

What is the purpose of installing a 'reflux valve' (non-return valve) on the discharge pipe of each pump inside a wastewater pump station?

• ATo prevent pumped sewage in the rising main from flowing back into the wet well when the…
• BTo regulate the flow rate of the pump to prevent motor overloading.
• CTo allow air to escape from the pump casing during priming.
• DTo redirect the flow back to the wet well if the downstream pressure becomes too high.

Wastewater rising mains are typically constructed from what material to withstand the high internal pressures and corrosive sewage gases?

• APolyethylene (PE100 or PE80) or Ductile Iron (DI)
• BUnreinforced Concrete (non-pressure)
• CGalvanized Mild Steel
• DCorrugated HDPE

How should the allowable depth of flow at Peak Wet Weather Flow be established for a new public gravity sewer?

• AApply the wastewater authority's depth-ratio and capacity criteria
• BAllow full-bore flow at PWWF because a gravity sewer needs no ventilation or surcharge al…
• CUse 0.9d nationwide because all authorities accept the same residual air-space requirement
• DUse 0.25d nationwide because lowering flow depth always improves capacity and self-cleans…