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CSLB Land Development Engineering study materials
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CSLB Land Development Engineering practice questions

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Question 1Site Planning and Land Use

A developer proposes a 40-lot single-family subdivision. Under the Subdivision Map Act, which map type is generally required for this project?

  1. Tentative parcel map
  2. Lot line adjustment
  3. Tentative and final subdivision map Correct answer.
  4. Final parcel map

Explanation

The Subdivision Map Act requires a tentative map followed by a final map for subdivisions creating five or more parcels. Parcel maps are used for four or fewer parcels. A lot line adjustment is not a subdivision and does not create new lots.

Question 2Site Planning and Land Use

A local agency is updating its general plan. Which element is mandatory under state law and addresses the location and extent of land uses?

  1. Land use element Correct answer.
  2. Circulation element
  3. Housing element
  4. Noise element

Explanation

The land use element is a mandatory general plan element that designates the distribution and intensity of land uses. It is the central element that other elements must be consistent with. The housing element is also mandatory but addresses housing needs specifically.

Question 3Site Planning and Land Use

A property is zoned R-1 with a 6,000 square foot minimum lot area. A lot created before the zoning ordinance took effect contains only 5,000 square feet. What is this lot commonly called?

  1. Conditional use lot
  2. Variance lot
  3. Nonconforming lot Correct answer.
  4. Overlay lot

Explanation

A lot that was legally created before current zoning standards took effect but does not meet current minimum area requirements is a legal nonconforming lot. It may generally be developed subject to local provisions. A variance is a separate discretionary approval.

Question 4Site Planning and Land Use

In site planning, what does the term 'setback' refer to?

  1. The width of the street right-of-way adjoining a lot
  2. The minimum required distance from a property line to a structure Correct answer.
  3. The maximum height of a building measured from grade
  4. The percentage of a lot that may be covered by structures

Explanation

A setback is the required open distance between a building or structure and a property line or other reference line. Setbacks control building placement and provide light, air, and separation. They are distinct from height limits and lot coverage.

Question 5Site Planning and Land Use

A city wants to allow a mix of residential and commercial uses in a specific corridor. Which planning tool is most directly suited to this goal?

  1. Open space easement
  2. Historic preservation district
  3. Floodplain overlay zone
  4. Planned unit development overlay Correct answer.

Explanation

A planned unit development or mixed-use overlay allows combining residential and commercial uses under flexible standards. It is commonly used to encourage mixed-use corridors. The other tools address preservation, flood hazards, or conservation.

Question 6Site Planning and Land Use

What is the primary purpose of a site plan review?

  1. To establish the assessed value of a property
  2. To verify that a proposed development meets zoning and design standards Correct answer.
  3. To set the interest rate on a construction loan
  4. To record the legal description of a parcel

Explanation

Site plan review is an administrative process that evaluates a proposed project against zoning, design, and development standards. It addresses layout, access, parking, and similar site details. It does not determine property value or record legal descriptions.

Question 7Site Planning and Land Use

Which of the following best describes the purpose of a general plan consistency requirement?

  1. Zoning and land use decisions must be consistent with the general plan Correct answer.
  2. Developers must own all adjoining parcels
  3. All parcels must be rezoned every ten years
  4. Building permits must be issued within thirty days

Explanation

State law requires that zoning ordinances and land use decisions be consistent with the adopted general plan. This ensures local decisions follow the community's long-range vision. It does not impose rezoning cycles or permit deadlines.

Question 8Site Planning and Land Use

A developer must dedicate land for a public park as a condition of subdivision approval. Which term describes this requirement?

  1. Encumbrance
  2. Easement
  3. Exaction Correct answer.
  4. Estoppel

Explanation

An exaction is a condition of approval requiring a developer to dedicate land, pay fees, or provide improvements. Parkland dedication is a common form of exaction. Easements and encumbrances are property interests, not approval conditions.

Question 9Site Planning and Land Use

A lot is 100 feet wide and 150 feet deep. Local zoning limits lot coverage to 40 percent. What is the maximum allowable building footprint area?

  1. 9,000 square feet
  2. 6,000 square feet Correct answer.
  3. 15,000 square feet
  4. 4,000 square feet

Explanation

The lot area is 100 feet times 150 feet, or 15,000 square feet. Forty percent of 15,000 is 6,000 square feet. Lot coverage limits apply to the building footprint area.

Question 10Site Planning and Land Use

A site slopes steeply from the street toward the rear of the lot. Which drainage approach best follows the principle of grading away from structures?

  1. Allow runoff to pond against the uphill retaining wall
  2. Level the entire lot to eliminate all slope
  3. Direct runoff toward the building foundation to consolidate flow
  4. Grade the pad so surface water drains toward the street or a designed swale Correct answer.

Explanation

Site grading should direct surface water away from foundations toward approved drainage features such as swales or the street. Ponding against walls or foundations can cause damage. Flattening the entire lot is often impractical and unnecessary.

Question 11Site Planning and Land Use

A proposed driveway serving a single-family home would cross a public sidewalk. What is typically required at the crossing?

  1. A curb ramp or driveway apron meeting accessibility standards Correct answer.
  2. A raised median in the street
  3. Removal of the sidewalk segment
  4. A permanent gate across the sidewalk

Explanation

Where a driveway crosses a pedestrian path, an accessible apron or ramp is generally required to maintain a usable walkway. This supports pedestrian safety and accessibility. Removing the sidewalk or adding gates would impair circulation.

Question 12Site Planning and Land Use

A developer wants to build on a lot that fronts a substandard-width street. Which issue is most likely to arise during subdivision review?

  1. The project may be denied or conditioned because street improvements are needed Correct answer.
  2. No review is needed because street width is a state matter
  3. The lot automatically becomes a legal nonconforming lot
  4. The zoning designation is voided by the street width

Explanation

Subdivision regulations typically require adequate street access and may condition approval on street improvements or deny projects with inadequate access. Street width is generally a local improvement standard. It does not void zoning or create nonconforming status.

Question 13Site Planning and Land Use

A project site contains a wetland. Which regulatory program most directly governs dredge and fill activities in that wetland?

  1. The Clean Air Act
  2. Section 404 of the Clean Water Act Correct answer.
  3. The National Historic Preservation Act
  4. The Fair Housing Act

Explanation

Section 404 of the Clean Water Act regulates the discharge of dredged or fill material into waters of the United States, including many wetlands. A permit from the U.S. Army Corps of Engineers is typically required. The other statutes address historic resources, housing, and air quality.

Question 14Site Planning and Land Use

A parcel is designated for low-density residential use in the general plan but is zoned for heavy industrial use. What is the most likely outcome when the inconsistency is identified?

  1. The parcel becomes unzoned
  2. The zoning should be amended to be consistent with the general plan Correct answer.
  3. Both designations remain in effect indefinitely with no action
  4. The general plan must be amended to match the zoning automatically

Explanation

When zoning conflicts with the general plan, the zoning ordinance should be amended to achieve consistency. The general plan is the guiding document under state law. Leaving both in effect is inconsistent with the consistency requirement.

Question 15Site Planning and Land Use

A developer proposes a project that would increase traffic on an intersection operating at an unacceptable level of service. Which mitigation measure is most directly related to traffic demand?

  1. Waiving the site plan review
  2. Requiring the developer to fund a traffic signal or turn lane Correct answer.
  3. Increasing the building height limit
  4. Reducing the required parking ratio

Explanation

Traffic impact mitigation commonly includes physical improvements such as signals, turn lanes, or fair-share fees. These directly address the added traffic demand. Reducing parking or waiving review does not mitigate the intersection impact.

Question 16Site Planning and Land Use

Under the Subdivision Map Act, what is the typical time period within which a local agency must act on a tentative map for a residential subdivision?

  1. 30 days
  2. 50 days Correct answer.
  3. 180 days
  4. 120 days

Explanation

The Subdivision Map Act generally requires action on a tentative map within 50 days of a complete application for most residential subdivisions. Extensions may be granted by mutual agreement. This timeline is intended to keep the review process predictable.

Question 17Site Planning and Land Use

A site plan shows a building placed close to the rear property line next to a single-family home. Which design consideration most directly addresses privacy impacts?

  1. Painting the building a lighter color
  2. Reducing the number of parking spaces
  3. Increasing the rear setback or adding screening Correct answer.
  4. Adding a monument sign at the entrance

Explanation

Rear setbacks and screening such as fences or landscaping reduce visual and privacy impacts on adjacent homes. These are common compatibility measures. Parking counts, signage, and paint color do not directly address privacy.

Question 18Site Planning and Land Use

A local ordinance requires that new development provide a percentage of affordable housing units or pay an in-lieu fee. What is this requirement commonly called?

  1. Transfer of development rights
  2. Floor area ratio
  3. Inclusionary housing requirement Correct answer.
  4. Density bonus

Explanation

Inclusionary housing policies require a portion of new residential units to be affordable or allow an in-lieu fee. A density bonus is a separate incentive that increases allowable units in exchange for affordable housing. Floor area ratio and transfer of development rights are different planning tools.

Question 19Site Planning and Land Use

A project site is in a seismic hazard zone with a known landslide risk. Which step is most appropriate before approving the project?

  1. Require a geotechnical investigation and appropriate design measures Correct answer.
  2. Approve the project because zoning permits the use
  3. Require only a landscaping plan
  4. Reduce the required parking to offset risk

Explanation

Sites with known geologic hazards generally require a geotechnical investigation to evaluate risk and identify mitigation measures. Approval should account for those findings. Zoning alone does not resolve safety hazards, and landscaping or parking changes do not address them.

Question 20Site Planning and Land Use

A city designates a historic district. A property owner wants to demolish a contributing building. What review is typically required?

  1. Historic resource or design review approval Correct answer.
  2. A conditional use permit for parking
  3. A variance for lot area
  4. A lot line adjustment

Explanation

Demolition of a contributing building in a historic district typically requires historic resource review or design review approval. This process evaluates the effect on historic character. Lot line adjustments, variances, and parking permits do not address historic resources.

Question 21Site Planning and Land Use

A developer proposes a project that would require removing mature heritage trees. Which mitigation approach is most consistent with standard practice?

  1. Avoidance first, then replacement planting at an approved ratio Correct answer.
  2. Increasing lot coverage to compensate for tree loss
  3. Relocation of every tree regardless of species
  4. Removal without replacement because the trees are on private land

Explanation

Tree protection ordinances generally prioritize avoidance and require replacement planting at an approved ratio when removal is unavoidable. Replacement ratios vary by ordinance and tree size. Increasing lot coverage does not mitigate tree loss.

Question 22Site Planning and Land Use

A site is located in a special flood hazard area. Which requirement most directly affects the finished floor elevation of a new structure?

  1. The structure must exceed the height limit
  2. The structure must be elevated above the base flood elevation Correct answer.
  3. The structure must be built at grade
  4. The structure must have a basement

Explanation

In special flood hazard areas, local floodplain ordinances typically require the lowest floor to be elevated to or above the base flood elevation. This reduces flood damage risk. Building at grade or with basements generally increases risk.

Question 23Site Planning and Land Use

A project requires a conditional use permit. Which statement best describes the nature of this approval?

  1. A ministerial approval that must be granted if the application is complete
  2. A discretionary approval based on findings that the use is compatible under conditions Correct answer.
  3. An automatic entitlement upon payment of fees
  4. A permanent right that cannot be revoked

Explanation

A conditional use permit is a discretionary approval that requires findings of compatibility and compliance with standards, often with conditions. It is not ministerial and may be revoked for noncompliance. Fees alone do not create entitlement.

Question 24Site Planning and Land Use

A developer proposes a mixed-use project in a transit priority area. Which policy approach most commonly supports such development?

  1. Elimination of pedestrian connections
  2. Increased parking minimums and lower density
  3. Mandatory single-use zoning
  4. Reduced parking requirements with increased density near transit Correct answer.

Explanation

Transit-oriented development policies often reduce parking minimums and allow higher density near transit to encourage ridership and walkability. Lower density and single-use zoning work against that goal. Pedestrian connections are typically enhanced, not eliminated.

Question 25Site Planning and Land Use

A city is preparing an environmental impact report for a project. Under CEQA, which statement best describes the purpose of the report?

  1. To set the property tax rate for the project site
  2. To approve the project regardless of environmental effects
  3. To identify significant environmental effects and feasible mitigation measures Correct answer.
  4. To replace the local zoning ordinance

Explanation

An environmental impact report under CEQA analyzes significant environmental effects and identifies feasible mitigation measures and alternatives. It informs decision-makers but does not itself approve the project. It does not set tax rates or replace zoning.

Question 26Site Planning and Land Use

A developer is preparing a tentative subdivision map for a 40-acre parcel. Which document most directly establishes the land uses and densities the map must be consistent with?

  1. The county recorder's parcel index
  2. The state building code occupancy tables
  3. The local general plan land use element Correct answer.
  4. The project's private marketing brochure

Explanation

In California, subdivision maps must be consistent with the local general plan, and the land use element is the component that designates allowed uses and densities. The map is reviewed against that designation before approval. Other documents do not set land use policy.

Question 27Site Planning and Land Use

A zoning ordinance sets a minimum front setback of 20 feet and a minimum side setback of 5 feet. A proposed house has a 22-foot front setback and a 4-foot side setback. How should the plan reviewer treat the proposal?

  1. Approve it, because average setbacks govern when one dimension complies
  2. Return it as noncompliant, because the side setback is below the minimum Correct answer.
  3. Return it as noncompliant, because both setbacks must match the minimum exactly
  4. Approve it, because the front setback exceeds the minimum

Explanation

Each dimensional standard in a zoning ordinance must be met independently; compliance with one does not offset a deficiency in another. A 4-foot side setback falls short of the 5-foot minimum, so the plan does not conform. The applicant would need a variance or a revised plan.

Question 28Site Planning and Land Use

A site plan shows a proposed commercial building whose loading area would face an adjacent single-family neighborhood. Which design approach best reduces land use conflict at that interface?

  1. Relocate the loading area to the interior side of the site away from residences Correct answer.
  2. Widen the driveway entrance at the street frontage
  3. Increase the building height to screen the loading area from view
  4. Add more parking spaces between the building and the property line

Explanation

Compatible siting places noise- and activity-generating uses away from sensitive neighbors and buffers the property line. Moving the loading area to an interior location reduces direct impacts on the adjacent homes. The other measures do not address the noise and activity conflict.

Question 29Site Planning and Land Use

A developer wants to subdivide a parcel into five lots served by an existing public street. Under the Subdivision Map Act, which approval is generally required before the lots can be sold?

  1. A design review approval from the architectural board
  2. A parcel map or tentative and final map, as applicable Correct answer.
  3. A coastal development permit in every case
  4. A conditional use permit for each lot

Explanation

The Subdivision Map Act requires local approval of a tentative map and a final or parcel map before subdivided lots may be conveyed. The type of map depends on the number of parcels and local ordinance thresholds. Other permits may be needed but do not substitute for map approval.

Question 30Site Planning and Land Use

A hillside site has shallow depth to bedrock and a history of slope failures on adjacent parcels. Before approving a residential subdivision, which action best supports a defensible finding that the site is safe for development?

  1. Increase the required lot size to reduce the number of homes on the slope
  2. Defer all geotechnical review until building permit issuance
  3. Rely on the developer's statement that prior grading on nearby lots performed well
  4. Require a site-specific geotechnical and geologic investigation with mitigation recommendations Correct answer.

Explanation

Where geologic or seismic hazards are indicated, approval should rest on a site-specific technical investigation that identifies hazards and prescribes mitigation. Generic measures or anecdotal evidence do not establish site safety. Deferring review to the building permit stage leaves the subdivision approval unsupported.

Question 31Grading, Drainage, and Stormwater Management

The primary purpose of a site grading plan is to do which of the following?

  1. Maximize the number of parking stalls on a parcel
  2. Set the property tax assessment for the parcel
  3. Determine the structural footing sizes for buildings
  4. Establish finished elevations that route water away from structures Correct answer.

Explanation

A grading plan establishes existing and proposed ground elevations and directs surface drainage away from buildings and toward approved discharge points. Footing design and parking counts are separate disciplines, though grading must accommodate them.

Question 32Grading, Drainage, and Stormwater Management

On a subdivision lot, the minimum finish grade fall recommended to move surface water away from a foundation is typically about:

  1. 25 percent
  2. 10 percent
  3. 0.5 percent
  4. 2 percent Correct answer.

Explanation

A minimum slope of roughly 2 percent (about 1 unit vertical in 50 horizontal) over the first several feet from the foundation is the common standard to prevent ponding against the structure. Steeper slopes may cause erosion and are hard to maintain.

Question 33Grading, Drainage, and Stormwater Management

A storm drain pipe is to be laid at a slope of 0.5 percent. For a 200-foot run, the total fall is:

  1. 2.0 feet
  2. 0.5 feet
  3. 4.0 feet
  4. 1.0 foot Correct answer.

Explanation

Fall equals slope multiplied by run: 0.005 × 200 ft = 1.0 ft. Keeping units consistent (percent converted to decimal) avoids order-of-magnitude errors.

Question 34Grading, Drainage, and Stormwater Management

In the Rational Method, the runoff coefficient C represents:

  1. The time for water to travel to the point of interest
  2. The infiltration rate of the underlying soil
  3. The storage volume of a detention basin
  4. The ratio of peak runoff rate to rainfall intensity times area Correct answer.

Explanation

The Rational Method is Q = CiA, where C is a dimensionless runoff coefficient reflecting the fraction of rainfall that becomes surface runoff for a given surface type. Travel time and storage are separate parameters.

Question 35Grading, Drainage, and Stormwater Management

Which of the following best describes a detention facility?

  1. It treats potable water before distribution
  2. It disposes of runoff by injection into a deep well
  3. It stores runoff temporarily and releases it at a controlled rate Correct answer.
  4. It permanently holds water year-round for recreation

Explanation

Detention temporarily stores stormwater and releases it slowly through a controlled outlet, reducing peak discharge to downstream channels. Retention, by contrast, holds water without a direct surface outlet.

Question 36Grading, Drainage, and Stormwater Management

A swale designed to convey stormwater along a street should generally have a longitudinal slope that:

  1. Is perfectly flat to encourage infiltration
  2. Reverses direction every 50 feet
  3. Exceeds 15 percent to ensure rapid drainage
  4. Provides adequate velocity to prevent standing water without causing erosion Correct answer.

Explanation

A lined or vegetated swale needs enough longitudinal slope to keep water moving and avoid mosquito-breeding ponding, but not so steep that flow velocity scours the channel. Designers check velocity against the lining's permissible value.

Question 37Grading, Drainage, and Stormwater Management

The term 'time of concentration' in stormwater hydrology refers to:

  1. The time between rain events
  2. The time for runoff to travel from the most hydraulically remote point to the outlet Correct answer.
  3. The duration a basin takes to drain completely
  4. The design life of a culvert

Explanation

Time of concentration is the travel time for water from the hydraulically most distant point of the catchment to reach the design point. It is used to select the rainfall intensity for the Rational Method.

Question 38Grading, Drainage, and Stormwater Management

Which soil property most directly governs how quickly water infiltrates during a storm?

  1. Hydraulic conductivity Correct answer.
  2. Unit weight
  3. Liquid limit
  4. Plasticity index

Explanation

Hydraulic conductivity (permeability) describes how readily water moves through soil and is the key parameter for infiltration rates. Plasticity and unit weight describe other engineering behaviors.

Question 39Grading, Drainage, and Stormwater Management

A parking lot is to drain to a catch basin. For a paved area, which surface slope is generally required to achieve positive drainage?

  1. 0.1 percent or flatter
  2. About 1 to 2 percent Correct answer.
  3. About 20 percent
  4. About 8 to 10 percent

Explanation

Paved surfaces typically use longitudinal and cross slopes around 1 to 2 percent to move water to inlets while remaining comfortable and safe for vehicles. Flatter slopes risk ponding; steeper slopes are hard to construct and may be unsafe.

Question 40Grading, Drainage, and Stormwater Management

A 4-acre site is 50 percent impervious with a runoff coefficient of 0.90 for pavement and 0.20 for the pervious area. The area-weighted composite C is closest to:

  1. 0.45
  2. 0.35
  3. 0.70
  4. 0.55 Correct answer.

Explanation

Composite C = (0.5 × 0.90) + (0.5 × 0.20) = 0.45 + 0.10 = 0.55. Weighting by area fraction is the standard approach for mixed land cover.

Question 41Grading, Drainage, and Stormwater Management

A designer must size a culvert to pass the 25-year storm. The 25-year peak flow is best described as:

  1. The maximum flow ever recorded at the site
  2. The flow that occurs every 25 months
  3. The flow that occurs exactly once every 25 years
  4. The flow with a 4 percent chance of being equaled or exceeded in any given year Correct answer.

Explanation

A 25-year return period corresponds to an annual exceedance probability of 1/25 = 0.04, or 4 percent in any year. Return period is a statistical average, not a fixed schedule.

Question 42Grading, Drainage, and Stormwater Management

A detention basin outlet is fitted with an orifice plate. Reducing the orifice diameter while keeping the head constant will:

  1. Have no effect on the release rate
  2. Eliminate the need for emergency spillway
  3. Increase the peak release rate
  4. Decrease the peak release rate Correct answer.

Explanation

Orifice discharge is proportional to the opening area, so a smaller diameter reduces the release rate for a given head. This lengthens detention time and lowers downstream peak flow.

Question 43Grading, Drainage, and Stormwater Management

Which practice is an example of a structural stormwater best management practice (BMP)?

  1. Public education on lawn fertilizer use
  2. Street sweeping programs
  3. Zoning limits on impervious cover
  4. A constructed wetland Correct answer.

Explanation

Structural BMPs are built facilities such as wetlands, bioswales, and basins that treat or detain runoff. Street sweeping, education, and zoning are non-structural or programmatic controls.

Question 44Grading, Drainage, and Stormwater Management

A grass-lined channel carries flow at a velocity that exceeds the permissible velocity for the grass cover. The most appropriate corrective action is to:

  1. Increase the flow depth to slow the water
  2. Reduce the channel slope or add a harder lining Correct answer.
  3. Narrow the channel to concentrate flow
  4. Remove the vegetation to reduce roughness

Explanation

Erosion occurs when velocity exceeds the lining's permissible value; reducing slope lowers velocity, and a harder lining raises the permissible velocity. Increasing depth or narrowing the channel generally increases velocity.

Question 45Grading, Drainage, and Stormwater Management

In a grading plan, 'mass diagram' analysis is used primarily to:

  1. Locate property lines
  2. Balance cut and fill to minimize haul and import/export of soil Correct answer.
  3. Compute the runoff coefficient
  4. Determine the storm drain pipe sizes

Explanation

A mass diagram plots cumulative cut and fill volumes along the site, helping the designer balance earthwork and minimize haul distances and offsite soil movement. Pipe sizing and hydrology are separate analyses.

Question 46Grading, Drainage, and Stormwater Management

A site discharges to a creek. To reduce the erosive energy of runoff entering the creek, a designer is most likely to specify:

  1. An energy dissipater at the outlet Correct answer.
  2. A smaller detention basin
  3. A larger upstream impervious area
  4. A steeper discharge pipe

Explanation

Energy dissipaters such as riprap aprons or stilling basins slow flow and spread it before it reaches the receiving channel, reducing scour. Steeper pipes and more impervious area increase energy.

Question 47Grading, Drainage, and Stormwater Management

A hydrologic study uses the SCS/NRCS curve number (CN) method. A higher curve number indicates:

  1. A longer time of concentration
  2. Greater runoff potential for a given rainfall Correct answer.
  3. A lower peak discharge
  4. Greater infiltration and less runoff

Explanation

The curve number ranges roughly from 30 to 100, with higher values representing more runoff-prone conditions such as impervious or poorly drained soils. Lower CN values indicate more infiltration and less runoff.

Question 48Grading, Drainage, and Stormwater Management

A residential lot has a rear yard that slopes toward the house. The most appropriate grading fix is to:

  1. Leave the slope and rely on the roof gutters
  2. Regrade to create a swale that carries water around the structure to the front or side Correct answer.
  3. Install a sump pump in the rear yard
  4. Add fill against the rear wall to raise the grade above the floor

Explanation

A graded swale that intercepts and redirects rear-yard flow around the building protects the foundation. Raising grade against the wall worsens the problem, and gutters alone cannot handle surface flow from the yard.

Question 49Grading, Drainage, and Stormwater Management

The primary function of a level spreader at the outlet of a stormwater conveyance is to:

  1. Increase flow velocity before discharge
  2. Distribute flow uniformly over a broad area to promote sheet flow and infiltration Correct answer.
  3. Filter sediment using a geotextile bag
  4. Measure the discharge rate

Explanation

A level spreader converts concentrated flow into sheet flow across a vegetated area, reducing erosion and encouraging infiltration. It does not accelerate flow or measure it.

Question 50Grading, Drainage, and Stormwater Management

A designer must verify that a proposed development will not increase the peak discharge to the downstream channel above pre-development levels for the 10-year storm. This requirement is best met by:

  1. Removing vegetation from the site
  2. Reducing the time of concentration
  3. Increasing the pipe size of the downstream channel
  4. Detaining post-development runoff and releasing it at or below the pre-development peak rate Correct answer.

Explanation

Peak-shaving is achieved by storing post-development runoff and releasing it slowly so the outflow does not exceed the pre-development peak. Enlarging the downstream channel or increasing runoff does not satisfy a peak-matching requirement.