Gravel Road


The purpose of this chapter is to address more complex Program policies that are not necessarily applicable to every project. This chapter contains policies and guidance on:

7.1 Stream Crossing Structural Replacement (Bankfull) Policy

This section applies to stream crossing replacements (not road drainage "crosspipes") on both Low-Volume funds and Dirt and Gravel roads.

7.1.1 Background

The goal of this policy is to limit the replacement of stream crossing structures to those which are negatively impacting streams. The best quantification of stream impact is the size of the existing structure related to the bankfull width of the channel. A channel’s bankfull width is the width of flow at a "dominate channel forming flow stage" where sediment and bed material is moved most effectively through the stream system. Although it varies, bankfull is typically associated with a flow level between one and two year recurrence. Stream crossing structures that are significantly less than the channel’s bankfull width are typically associated with many problems including gravel deposition above the road and excessive stream scour and erosion below the road. The policy below limits paying for structural replacement on pipes over 4’ in diameter to only those locations where the existing structure is less than 75 percent of the bankfull channel width. These structures are most likely to be causing negative stream impacts, and are most likely to be sources of perpetual maintenance and road impacts to local municipalities (gravel bar removal, erosion, etc.). In addition, any new structures must have a width at least equal to the channel’s bankfull width. Bankfull structures have been shown to be both cost-effective over their lifetime and provide significant aquatic benefits. In addition, installing bankfull structures helps reduce annual maintenance costs, and can prevent road damage and road closures due to flooding.

7.1.2 Replacement of Road/stream Crossing Structures

The purpose of this policy is to determine eligibility for stream crossing structural replacement with Program funds. Environmentally Sensitive Maintenance practices applied to the surrounding stream crossing structure area (road, stream banks, ditches, headwalls, wingwalls, high water bypass etc.) are still eligible Program expenses around all stream crossings regardless of bankfull measurements. Within the limits described below, the final decision on funding structure replacement, along with the type of structure used (pipe, box, etc.), is at the discretion of local QABs. Individual QABs can enact stricter polices within their counties, for example requiring structures to be 50 percent bankfull instead of 75 percent to be eligible for replacement, or requiring new structures to be 1.2 times bankfull width. These qualifications for replacement with Program funds do not exempt projects from any permitting or engineering requirements. Engineers should be made aware of this policy early in the planning process, as stream crossing designed solely based on hydraulic capacity are typically smaller than a bankfull structure. Districts should hold an on-site pre-design meeting with the applicant and their engineer prior to the structure design process and application development. Districts may develop local polices requiring pre-application or pre-design meetings.

Bankfull structures will not only accommodate the hydraulic capacity of the stream, but will allow for better stream function through the road in regards to bedload movement, sediment and debris transport, and aquatic organism passage. Stream crossing replacements can be funded as standalone projects, or as part of a larger Program project. The Program’s "Stream Crossing Evaluation Form", along with guidelines on bankfull determination, can be found in Appendix E.

Stream Crossing Replacement Policy

EXISTING stream crossing structures with an opening equal to or less than 13 square feet (equivalent to a 48 " diameter round pipe):

  • Are eligible to be replaced with Program funds.
  • The NEW REPLACEMENT structure must (all four):
  1. Have a structure width at least equal to bankfull width (100 percent ratio).
  2. Be properly aligned with the channel when possible.
  3. Consider additional floodplain connectivity when possible.
  4. Be designed and constructed to accommodate the passage of aquatic organisms through the structure.

EXISTING stream crossing structures with an opening of more than 13 square feet (equivalent to a 48 " diameter round pipe):

  • In order to be eligible for replacement, EXISTING structures must (all three):
  1. Have a structure to bankfull width ratio of 75 percent percent or less.
  2. Show signs of streambank erosion.
  3. Show signs of streambed erosion/aggradation.
  • The NEW REPLACEMENT structure must (all four):
  1. Have a structure width at least equal to bankfull width (100 percent ratio).
  2. Be properly aligned with the channel when possible.
  3. Consider additional floodplain connectivity when possible.
  4. Be designed and constructed to accommodate the passage of aquatic organisms through the structure.

Round pipes over 36" in diameter are not permitted for use in DGLVR funded stream crossings. Oval or squash pipes are acceptable. This applies only to stream crossing replacements. Round crosspipes are standard and acceptable for road drainage.

Existing structures that do not meet the above criteria are not eligible for replacement (materials, equipment, or labor) with Program funds. This policy applies to replacement of structures and does not prohibit work adjacent to the structure.

Considerations for multiple pipes

Stream crossings consisting of multiple "side-by-side" pipes are associated with a wide variety of problems including clogging and channel stability issues. Installation of multiple pipe structures is NOT permitted with Program funds (high-water or overflow pipes are permitted, but do not count towards bankfull capacity). In addition, existing stream crossings consisting of multiple pipes are eligible for replacement regardless of their relationship to the bankfull measurement, as long as they are replaced with a single opening structure of at least bankfull width. This policy applies to multiple pipes only, not multi-cell bridges.

Policy Application to Small Streams

For Program purposes, the stream crossing policy applies to situations where streams, including intermittent channels, with identified bed and banks are flowing into the road or the uphill ditch. Contact the State Conservation Commission in questionable circumstances. In order for policy exceptions on "questionable stream" channels, Districts must obtain written approval from the Commission prior to contracting the project.

Routine Maintenance

The Program has never paid for "routine or regular maintenance" such as simply grading roads. Similarly, regular maintenance of stream crossing structures is not eligible for funding. This includes work items such as culvert lining, extending undersized stream crossings, bridge deck repair, etc. that provide minimal environmental improvements.

Stream Crossing Replacement Notification

Conservation Districts are required to notify the SCC of proposed stream crossing replacements as soon as practical before a contract is signed. An online notification system is available by logging in to the Centers website (same log-in as accessing the GIS system) at

Driving Surface Aggregate7.2 Driving Surface Aggregate (DSA)

This section applies primarily to Dirt and Gravel funds, but DSA may have limited use under Low-Volume funds, such as the conversion of a paved road back to gravel. Technical details for DSA including placement and purchasing specifications are not included in this administrative manual. See the Center’s Aggregate Handbook for technical documentation.

7.2.1 DSA Overview

DSA is a crushed stone mixture developed by the Center in 2001 to be used as a wearing course for unpaved roads. DSA is designed to achieve maximum density compared to other aggregates in order to resist erosion and support traffic. DSA has a few key differences compared to traditional aggregates such as PennDOT 2A or 2RC:

  • Well graded to include a range of rock sizes from 1.5" to "stone dust".
  • 10-15 percent of the material is composed of "rock fines" that bind the material together (up to 17% fines if Plasticity Index is less than 2).
  • Placement by motor paver is highly encouraged, and required for placements over 1,000 tons.
  • Several other requirements including a maximum plasticity limit, a pH range, a minimum hardness specification, and optimum moisture requirements.

Driving surface aggregate meeting the Commission’s specification is the only approved road surface material that may be purchased (for D&G projects) with Program funds. The only exception to this is on road fill projects. Projects that involve an average thickness of one foot or more (including surface) of road fill material may utilize an alternative aggregate to cap the newly added road base.

7.2.2 Use of DSA

The Program goal is to improve water quality. DSA is designed to resist erosion and stand up to the forces of traffic. DSA has been proven to reduce sediment loads compared to traditional aggregates by as much as 90 percent, and reduce dust by as much as 75 percent. Since DSA was designed to resist erosion, it was originally intended to be placed on sections of road adjacent to streams where draining road runoff to the waterway is unavoidable. Over the years, DSA has evolved into a "standard practice" on projects in many districts, and is being overused. DSA is NOT a required component of every Program project. The extent to which DSA is used on projects is at the discretion of individual Districts and QABs. When DSA is used as part of a project, it should be the very last phase of the project. DSA alone does not constitute a comprehensive Program project. All possible base and drainage improvements (new pipes, underdrain, road fill, French mattresses, etc.) must be completed first to reduce environmental impacts of the road and extend the longevity of the DSA. Avoid placing DSA on entrenched roads, or on roads where surface drainage issues are not resolved.

7.2.3 DSA Certification

DSA must be placed in accordance with the DSA specification and certification found in the DSA Handbook. A DSA certification is required for every project where DSA is used. The DSA certification does not apply to an entire quarry. The DSA certification applies only to a particular source or pile of DSA that is being purchased. Additional certifications are required if the quarry changes the DSA production process (for example switching to a different seam of stone). The DSA certification must be obtained by the grant recipient before aggregate is placed, and must be kept with project files.

7.2.4 DSA Quality Control

DSA must be sampled and tested by an independent lab before it is delivered to a project site. Sampling can be done by district representatives following the guidelines in the Aggregate handbook. DSA sampling, testing, and approval is "pile-specific", not "quarry-specific". Testing must be done on the aggregate pile that is directly supplying the job. The costs of testing can be incorporated into project costs, or paid out of a district’s admin/education funds. Sampling can also be done by the Center’s "DSA Clearinghouse".

The Center will act as a "DSA Clearinghouse" for DSA projects. The purpose of this DSA Clearinghouse is to ensure quality DSA purchase and placements for districts statewide by:

  • Visiting and talking with quarries to ensure they understand the DSA requirements.
  • Collecting samples and performing testing to ensure DSA meets all material requirements before delivery and placement.
  • Keeping records of aggregate testing to avoid duplicating efforts.
  • Establishing a central point of contact for quarries on DSA issues.
  • Assistance with contractor coordination.
  • On-site assistance during DSA placement.

If districts plan to use the DSA Clearinghouse, it is recommended that they contact the Center when a potential DSA supplier is chosen, at least 30 days before placement. Notification can be made utilizing the DSA Purchase Notification Form, provided in the Aggregate Handbook, or on the Center’s website. If districts choose to sample their own DSA, they should share testing results with the Center in order to provide a more comprehensive statewide database and avoid duplicate testing.

7.3 Full-Depth Reclamation (FDR)

7.3.1 Program Eligibility

FDR is an eligible expense in the Program, at the discretion of individual districts, for use on paved Low-Volume Road (LVR) projects. FDR is not an eligible expense on unpaved roads. FDR shall not be funded on paved LVR roads with DGLVR Program funds unless all applicable drainage improvements and Environmentally Sensitive Maintenance practices have been employed, as road owners are hesitant to install drainage practices at a later point when it would disturb the new road base. Shallow surface grinds for the purpose of road resurfacing are not considered FDR projects. FDR is a major rehabilitation technique in which the full depth (minimum 6") of the surface and predetermined portion of the underlying base is uniformly pulverized and blended to provide a stronger, homogeneous road base.

7.3.2 Alternatives to FDR

FDR is an expensive process that may not be necessary everywhere it is proposed. When considering funding FDR projects, consider alternative base improvement techniques such as:

  • Imported fill: Importing fill to raise the elevation of a road can be less expensive than FDR in some cases. Entrenched roads in particular will benefit from road fill to eliminate drainage issues while providing a sound road base.
  • French Mattress: In some cases, road base instabilities are a direct result of spring and seeps coming up near or under the road. French mattresses provide excellent road base while insuring that wet areas around and under the road will not affect the road above.
  • Geo-synthetics: The use of geo-synthetics such as geogrid can increase the structural strength and stability of the road base. Geogrid is an excellent solution to fix base problems and is cost effective on small projects.

7.3.3 Program FDR Requirements:

If a district chooses to fund an FDR project, the following requirements apply:

  • The Center must be made aware of the proposed FDR project before a contract is signed. A site visit from Commission or Center staff may be requested.
  • FDR must follow specifications in PennDOT Publication 447 (Approved Products for Lower Volume Local Roads)
  • The mix design for FDR projects must be determined by an independent third-party.
  • FDR is a base stabilization technique and does not provide a final running surface. Consideration for asphalt, "tar and chip", or some other final running surface must be part of the planning for FDR projects.
  • Any additives or binding agents used in chemical stabilization must be on the Program’s "Approved Products" list, detailed on the Center’s website.

7.4 Low Volume Road Specific Guidance

This section applies only to Low Volume funds, not Dirt and Gravel funds. The previous guidance and policy in this manual also applies to LVR projects and funds. For the purposes of the LVR Program, a "paved" road is defined to include any road surfaced with asphalt, "tar and chip", "chip seal", bitumen, concrete, or other asphalt-like coating.

7.4.1 LVR Guiding Principals Project Focus

The focus of road projects in the LVR portion of the Program should be on similar ESM principles that have been used in the Program since its inception. Projects in the LVR Program must contain benefits to both the road systems (improved drainage, reduced surface, ditch and bank erosion, smoother surface, more durable surface, reduced maintenance costs, etc.) and the environmental systems (water quality, stream quality, reduced storm water flows, improved air quality, increased infiltration). The balance between road improvements and environment benefits should be considered in the local QAB/district project ranking criteria and funding decisions. Long Term Benefits

Similar to Dirt and Gravel Projects, the focus of LVR projects should be on long-term road and environmental improvement projects.

  • Routine maintenance of LVR or storm water systems such as cleaning inlets, street sweeping, crack sealing, etc. is not eligible for funding under this Program.
  • Program funds should not be used to pay for deferred or neglected maintenance on drainage/storm water systems without road improvements.
  • Program funds should not be used to fund any LVR issues that do not provide a long term benefit to the road and to the environment. Mistakes/design Errors

Program funds should not be used to correct recent mistakes and or design errors on LVRs that are the responsibility of the original project engineer or construction firm. If recent (within its reasonable design lifespan) LVR construction projects contain design or construction flaws, correction of these problems should be the duty of the project’s engineer or contractor of record, and LVR funds should not be allocated for these purposes. Project Eligibility

In order to be eligible for LVR funding, a road must have an existing paved (including chip sealed) surface, and it must have a verified average daily traffic count of less than 500 vehicles per day (according to Commission guidance). For more information on traffic count guidance, see section 7.5.

All projects must apply ESM principles and practices to address an environmental concern directly related to the road, make improvements to the road system, or to meet all other Program requirements (ie. permits or approvals). The project eligibility requirements in section 3.7 of this manual apply to Low-Volume Roads.

7.4.2 LVR Project Guidelines Paying for Asphalt or Other Surfacing

Resurfacing paved roads (sealing or paving) is not a primary focus of the LVR Program component. Resurfacing costs can be considered by a district as a component part of a larger ESM project. It is at the discretion of individual districts and QABs whether resurfacing costs (sealing or paving) will be funded through the Program, either on individual projects or as countywide policy. Before funding any resurfacing work on projects, the following ESM principles must be addressed:

  • Drainage issues
  • Base instability issues
  • Other necessary and appropriate issues such as bank stability, road entrenchment, vegetation, etc. Surfacing Unpaved Roads

It is not the intent of the Program to encourage the sealing or paving of existing dirt or gravel roads and converting them to sealed or paved low-volume roads. While eligible entities may choose to seal or pave a DGR project on their own at some future point in time, no Program funds should be utilized for the specific purpose of converting unpaved roads to paved or "tar and chip", unless otherwise approved by the Commission. Reclaiming Paved or Sealed Roads to Gravel

The Program recognizes the value of converting a poorly constructed or poorly maintained paved low-volume road into a high quality gravel through full depth reclamation or other similar processes. Districts may utilize either dirt and gravel, or low-volume road program component funds for these purposes.

7.4.3 LVRs in Urban Areas

Many ESM principles and practices in use by the Program can be readily adapted to paved LVRs in a rural environments. LVR funding, however, is not limited to rural roads or rural environments. LVR projects in urban areas will require a new set of best management practices (BMPs) that will take some time to develop and disseminate through the Program. The level of focus in rural and urban environments will be at the discretion of districts and QABs.

In order to increase the knowledge base of potential urban LVR BMPS, district should contact the Center when planning to fund an urban LVR project that is outside of "traditional ESM practices". This will give the Center opportunity to provide input to these urban projects prior to QAB approval, and will help the Center to increase the knowledge base of urban BMPs for statewide education purposes.

The LVR portion of the Program is not JUST a storm water program. Projects, especially in urban areas, need to strike a balance between environmental improvements and road improvements. It will be up to districts and QABs to determine the proper balance for projects in their counties.

7.4.4 Safety Considerations

The Commission recognizes the fact that many LVR component projects will have higher levels of daily traffic and higher levels of posted speed than projects on unpaved roads. Grant Recipients are required to follow the same safety protocols as with all other road work (flaggers, signs, etc). The funding of any traffic control and safety components of a Program project is at the discretion of the district.

7.5 Traffic Counts for Low-Volume Roads

Before a contract can be signed for a low-volume road project, the applicant is responsible for validating that the road has 500 vehicles per day or less consistent with Commission and any local QAB policy. The Program’s "Traffic Count Validation form and Instructions" can be found in Appendix F.

  • Applicant is responsible for providing traffic counts before a contract can be signed.
  • A traffic count is not required in order to submit an application, unless required by local QAB policy.
  • The district is responsible for verifying that a count exists, and that the count meets the criteria established in state and local policy.
  • Traffic counts are considered valid for a period of five years, provided there are no new significant changes in traffic flow volumes or patterns.
  • Documentation of traffic counts using a signed "Traffic Count Validation Form" must be retained with project files according to the Commission’s record retention policy. Districts may opt to include the completed traffic count validation form as an attachment to the project contract.
  • Districts may, at their discretion, use administrative and education funding to facilitate or support traffic counts for applicants. Districts should ensure that all potential applicants have equal access to any traffic count facilitation measures they may employ.
  • Traffic counts only apply to a segment of road between intersections, not to an entire length of road. Application sites that include intersections may require multiple counts.
  • Traffic counts should be done on the proposed project location, or on a road that ensures that traffic on the project location can be determined.

7.5.1 OPTION A: Validate with Existing Traffic Count Data or Extrapolation Use of Existing Data

Existing traffic counts can be used to verify road eligibility for LVR funding. Existing data must have been collected within the previous five years and conform to the Program’s Level 2 count protocol at a minimum. "Estimated" traffic counts that exist for many municipal roads cannot be used. Extrapolation of Existing Data

It is permissible to use existing data for roads with 500 vehicles per day or less to logically extrapolate to subsidiary roads. (For example, a spur road between two state roads where both state roads have less than 500 vehicles per day must also have less than 500.) This extrapolation of data can be used to verify that a road has 500 vehicles per day or less without performing a count. This extrapolation of traffic counts must prove the ADT on the road is 500 or less to be eligible for LVR funding. Potential sources of existing traffic count data include:

  • State Roads: Traffic Volume Maps
  • Local Roads: PennDOT regional offices or County Planning Commissions.

7.5.2 OPTION B: Validate with Level 1 Count: 2 Hour Count

An applicant may do a Level 1 count to determine the traffic count on a potential project site. This involves counting traffic for a two hour period, either by hand tally, video recording, or an automated traffic counter. A Level 1 count of 500 vehicles per day or less will qualify the road for LVR funding. A Level 1 count must meet the following criteria:

  • It must be conducted between March 1 and the week before Thanksgiving.
  • It cannot be conducted on a holiday, or the day before or after a holiday.
  • It must be conducted on a Tuesday, Wednesday, or Thursday
  • It must be conducted for a minimum of two consecutive hours between 3:00 pm and 6:00 pm.
  • Only the number of vehicle passes is counted, regardless of direction of travel or type of vehicle.
  • The traffic count for the time period will be adjusted to a 24 hour period by simply multiplying the 2 hour count volume times twelve (12)
  • Applicants may skip the Level 1 count and go straight to a Level 2 count if desired
  • Only licensed motor vehicles should be counted.

If a Level 1 count produces a count of 500 vehicles per day or less, the project on the road is considered eligible without a Level 2 count. If a Level 1 count produces a count of more than 500 vehicles per day, it does not disqualify the road, but necessitates a Level 2 count because of its increased accuracy. The purpose of a Level 1 count is to provide a reasonably accurate traffic count with minimal time investment. Level 1 Count Examples

Example 1: A traffic count for two consecutive hours between 4:00 pm and 6:00 pm produces a count of 25 vehicles. 24hours (per day) / 2hours (per study) = 12

12 x 25 =300 average daily count.

This worksite would be eligible (no Level 2 count needed).

Example 2: A traffic count for two consecutive hours between 3:30 pm and 5:30 pm produces a count of 53 vehicles. 24hours (per day) / 2hours (per study) = 12

12 x 53 = 636 average daily count.

This does not disqualify the road. It simply means that a more accurate Level 2 count is required if the applicant wants to continue to pursue Program funding.

7.5.3 OPTION C: Validate with Level 2 Count: 24 hour Automated Count

A Level 2 count involves the placement of an automated traffic counter on the road for a minimum period of 24 hours. Note that these are the minimum criteria for a count. More comprehensive or longer counts can be substituted as long as they meet the minimum requirements below for a "Level 2 count". A Level 2 count of 500 vehicles per day or less will qualify the road for LVR funding. Level 2 counts supersede Level 1 counts if there is a discrepancy. A level 2 count must meet the following criteria:

  • It must be conducted between March 1 and the week before Thanksgiving.
  • It cannot be conducted on a holiday, or the day before or after a holiday.
  • It must be conducted between 12 AM Tuesday and 12 AM Friday.
  • It must be conducted for a minimum of 24 consecutive hours.
  • Only the number of vehicle passes is counted, regardless of direction of travel or type of vehicle.

If a Level 2 count produces a count of 500 vehicles per day or less, the project on the road is considered eligible. If a Level 2 count produces a count of more than 500 vehicles per day, a project on that road is not eligible for LVR funding. 24 hour counts do not have be broken up by hour or any smaller time unit.

The criteria described in the Level 2 count represent a "minimum acceptable criteria". Counties may use or adopt more stringent traffic count requirements as long as it meets or exceeds the requirements here. (A more stringent requirement is a count that provides more statistically accurate data. For example: requiring Level 2 counts for all roads, requiring 48 hour counts, or requiring hourly totals on counts to provide information to PennDOT.)

7.5.4 Seasonal Activities and Special Circumstances

A traffic count survey cannot be conducted in a timeframe or manner that intentionally causes artificially low average daily traffic counts on a particular road segment. This includes conducting a traffic count during summer recess for a school access road, or conducting a traffic count when access to a road segment is temporarily or partially restricted or reduced (i.e. detoured, weight, or size restricted, etc.) or conducting a traffic count in any other timeframe or manner that intentionally causes low average daily traffic counts.