Entry Type ID Date Applicable Rating System Primary Credit Inquiry (LIs) Ruling (LIs) Related Addenda/LIs Related Resources Campus Applicable Internationally Applicable Country Applicability Reference Guide (Addenda) Page (Addenda) Location (Addenda) Description of Change (Addenda) "Reference Guide Correction" "100000310" "2010-11-03" "New Construction, Schools - New Construction, Core and Shell" "None" "None" "Green Building Design and Construction, 2009 edition" "102" "Economic Issues" "In the fourth and fifth lines of the paragraph, remove both instances of ""?""" "Reference Guide Correction" "100000311" "2010-11-03" "New Construction, Schools - New Construction, Core and Shell" "None" "None" "Green Building Design and Construction, 2009 edition" "104" "Table 2" "In the third cell of the table\'s title row, replace ""Rage"" in the column header with ""Range"" so it becomes ""Probable Range of TSS Removal""" "LEED Interpretation" "10109" "2011-11-01" "New Construction, Core and Shell, Schools - New Construction, Retail - Commercial Interiors, Healthcare" "How can a project earn exemplary performance for Stormwater Quantity and Quality?" "The exemplary performance requirements for SSc6.1 Stormwater Quantity and SSc6.2 Stormwater Quality listed in the LEED Green Building Design & Construction Reference Guide call for (1) a comprehensive approach to capture and treat stormwater runoff and (2) demonstrated performance above and beyond the credit requirements. To expand and clarify what these two requirements refer to, the following additional guidance is provided.\n\nSSc6.1 Stormwater Quantity\nTo demonstrate a comprehensive approach and performance above and beyond the credit requirements, the stormwater management strategies must:\n1. Address runoff from the entire development footprint of the site using Low Impact Development (LID) practices. \n2. Achieve the following stormwater quantity performance:\na. Case 1, Option 1: Achieve a post-development peak discharge rate and quantity that is equivalent to those calculated for the pre-Columbian site conditions.\nb. Case 1, Option 2: No EP available for his compliance path.\nc. Case 2: Achieve a 50% reduction in the volume of runoff during the 2-year 24-hour design storm.\n\nLID is defined as an approach to managing stormwater runoff that emphasizes on-site natural features to protect water quality by replicating the pre-development hydrologic regime of watersheds and addressing runoff close to its source. Examples include better site design principles such as minimizing land disturbance, preserving vegetation, minimizing impervious cover, and design practices like rain gardens, vegetated swales and buffers, permeable pavement, and soil amendments. These are engineered practices that may require specialized design assistance.\n\nSSc6.2 Stormwater Quality\nTo demonstrate a comprehensive approach and performance above and beyond the credit requirements, the best management practices employed must be non-structural, conforming to LID practices as defined above, and should be designed to remove at least 80% of the average annual total suspended solids (TSS) from twice the rainfall volume required for the base credit (i.e, runoff generated from 1 inch of rain in an arid climate, 1.5 inches of rain in a semiarid climate, and 2 inches of rain in a humid climate).\n\nTo document compliance with these requirements, a detailed narrative or stormwater management plan summary should be provided that describes the exemplary performance approach and includes calculations that clearly highlight compliance with the exemplary performance requirements. As the exemplary performance requirements for these two credits overlap considerably, only one SSc6 EP point is available to projects." "None" "None" "LEED Interpretation" "1559" "2006-09-04" "New Construction, Existing Buildings, Core and Shell, Schools - New Construction" "The intent of SSc6.2, interpreted from the manual and subsequent CIRs, is to minimize the disruption and pollution of natural water bodies by contaminated stormwater. To meet the Credit Intent, the Requirements specify active TSS treatment of stormwater, using BMPs that reduce the percentage of contaminants in the runoff. The project site is 5.24 acres and has 3 acres of impervious surfaces. The site is part of an overall 75 acre master plan that empties it\'s stormwater into Tributary A, North Buffalo Creek. There is an existing retention pond in the middle of the Park that is adjacent and just North of the Site (not located within the project site for LEED). The drainage area to the pond is +/- 44 acres of highly developed office and commercial property and 70% of this area is impervious. The project site is included within these 44 acres. The pond drain is an open pipe with headwall. The outlet pipe runs underground through the Site and empties upstream of the proposed building into Tributary A, North Buffalo Creek. The Site has an existing storm sewer outflow system designed and sized for future development of this site plus the upper buildings and parking lots (approximately 9 acres). This system empties directly into Buffalo Creek downstream of the proposed LEED building. We propose to modify the spillway of the existing pond to treat approximately 110,000 C.F. of stormwater for the extended acreage in lieu of treating stormwater only for the project site. Of the overall 75 acre master plan, +/- 44 acres runoff into the pond and contain untreated water, entering and exiting the pond without allowing pollutants and suspended solids to be removed. Given the existing stormwater system, it does not make sense to treat stormwater on the project site, but rather to treat all of the stormwater from the larger 44 acre site. We believe that treating the 44 acres will meet and exceed the intent of the credit for the following reasons: 1) We will create a new spillway with an orifice that stores the first inch of runoff for the entire 44 acres, which will achieve 85% TSS removal based on existing monitoring and will be constructed in accordance with the Greensboro Stormwater Design Manual. 2) The project site is part of a 75 acre master plan and by creating the spillway we will be maximizing the positive impact on the overall water quality entering Tributary A, North Buffalo Creek for an area that is 25 times the project site\'s size. The spillway will also resolve any associated stormwater system issues that were previously designed and constructed in a less environmentally friendly manner. We believe that we meet and exceed the intent of SSc6.2 because we are aiding in the overall water quality improvement and pollution minimization for the Buffalo Creek through stormwater quality control and therefore will earn this credit. Please confirm that achieving the treatment requirements for the larger 44 acre site will enable the project to earn the credit and perhaps be eligible for an exemplary performance ID credit. Also please confirm that we will be able to earn this credit by treating the Stormwater outside the project site as defined for the LEED submission." "Yes, achieving the TSS removal requirements for the larger 44 acre site as described will warrant the award of SS Credit 6.2. In accordance with the LEED-NC Application Guide for Multiple Buildings and On-Campus Building Projects (AGMBC), a centralized approach to stormwater management is acceptable. Submittal documentation will require the project team to demonstrate that the centralized BMP adheres to the credit requirements for all current development within the site serviced by the BMP. However, the project will not be awarded an Innovation in Design credit for Exemplary Performance of SSc6.2 as a result of these efforts. The approach of modifying the spillway to treat the stormwater for the extended acreage requires the BMP to be able to treat all current and future development. Therefore, the proposed BMP meets, but not exceed the requirements of this credit. Furthermore, page 85 of the LEED-NC v2.2 Reference Guide states that there is no exemplary performance point available for this credit.\n\nUpdate April 15, 2011: Please note that all 2009 projects in multiple building situations must follow the 2010 Application Guide for Multiple Buildings and On-Campus Building Projects, located here: https://www.usgbc.org/ShowFile.aspx?DocumentID=7987. 2009 project teams should check this document for up to date guidance on all multiple building issues. Applicable Internationally." "None" "None" "X" "LEED Interpretation" "1662" "2007-01-27" "New Construction, Existing Buildings, Core and Shell, Schools - New Construction" "My question is regarding Stormwater Quality Control. We are working closely with the Maryland Department of the Environment (MDE) to meet or exceed their requirements for water quality (as well as quantity) management measures. We are using BMPs such as bio-retention, wet swales, sand filters, green roofs, etc. All of the phases of construction are reviewed, approved, and inspected by MDE for sediment control and stormwater management measures. MDE\'s stormwater quality requirements for a re-development site are different than for previously undeveloped land. MDE requires that a minimum of 20% of the pre-existing impervious acreage, and 100% of the new impervious area (area that exceeds the previous amount of impervious acreage) be treated with water quality BMPs. During the seminar we were told that when questions such as this arise, it is important to look at the Intent of the credit. Credit 6.2 Intent states: ""Reduce or eliminate water pollution by reducing impervious cover, increasing on-site infiltration, eliminating sources of contaminants, and removing pollutants from stormwater runoff"". I believe without a doubt that we are fulfilling that stated intent on this project. In reading the requirements for SS 6.2 it is not clear to me whether USGBC will accept the same type of ""philosophy"" as MDE for water quality treatment for a re-development site or whether the entire impervious area for the site would have to be treated by BMPs in order to receive this credit." "While the intent of the MDE is laudable, the requirements cannot be considered directly equivalent to LEED requirements. In particular, LEED does not distinguish between pre-existing impervious areas and new impervious areas; the entire impervious area must be considered. To demonstrate credit compliance the project should submit calculations demonstrating that the required TSS and TP removal rates as outlined in the LEED-NC v2.1 Reference Guide are met for the entire site." "None" "None" "LEED Interpretation" "1700" "2007-03-15" "New Construction, Existing Buildings, Core and Shell, Schools - New Construction" "Some LEED projects sites might include areas which the owner desires to not graded, and plans to restore with landscaping and dedicate as open space. If the project owner decides to do the following items listed below can the space be excluded from the stormwater treatment requirements of this credit? (1) The part of their site is not developed or graded, and was not mass graded by a prior owner. (2) The part of their site is dedicated as open space, and restored if necessary. (3) The part of their site is dedicated as open space, and directly connects to other natural open space thereby increasing native habitat areas. (4) Stormwater runoff from the developed part of the site is fully treated to meet the requirements of this credit. If the above is not enough, what other measures would the project need to undertake to avoid intercepting stormwater from a natural, dedicated open space area simply to treat it to earn this LEED point? Intercepting storm water from such an area as the one described simply to treat it and earn this LEED point would be very harmful to the intent of increasing biodiversity by dedicating and restoring natural open space. If treatment must occur in such spaces then owners would be more likely to develop the area than to dedicate and restore it." "In this instance, to achieve this credit without intercepting stormwater from the natural landscape, the submittal must demonstrate that stormwater runoff from the site\'s development footprint is fully treated to meet the requirements of this credit AND that the remaining natural landscape does not contribute to suspended solids or phosphorous runoff. In addition to the required documentation, please provide the entire site plan, including topography, that highlights the area of natural landscape. Applicable Internationally." "None" "None" "X" "LEED Interpretation" "2077" "2008-04-09" "New Construction, Schools - New Construction, Core and Shell" "For Sustainable Site Credit 6.2, LEED refers to the US EPA stormwater best management practices, and also recognizes other programs such as at the state level. The US EPA document recognizes state programs as well. Due to the more established design criteria described in the NCDENR (North Carolina) stormwater best management practices design guide, and our familiarity with the NC program, we plan to use the NC program for determining design requirements for a wet pond, which is pre-qualified by the state program to eliminate 85% of TSS (LEED requirement is 80%). We (the engineering firm) are located in North Carolina, but our project is in Central America, and there are no developed programs or design guidelines for TSS removal where our project is located. When the site soils information is available, we will select a comparable design criteria from the NC design guide in terms of applicable soil qualities (water infiltration and suspended particle attributes), and use the appropriate NCDENR method to design the wet pond. Is this an acceptable path to obtaining Sustainable Site Credit 6.2 for our situation?" "The proposed path of using a qualified best management practice design guideline in combination with local soils information is acceptable for this credit, given that no local design standards exist for this purpose. The description provided does not mention use of local rainfall data, but clearly the sizing of the wet pond should also be based on local rainfall as opposed to assumptions for North Carolina. Applicable Internationally." "None" "None" "X" "LEED Interpretation" "2087" "2008-04-24" "New Construction, Schools - New Construction, Core and Shell" "For this project, the proposed condition reduces the existing impervious area by 38% below the existing condition, therefore the project received a waiver for storm water management, quantity control. Stormwater management requirements were met by reducing the existing impervious area on site. The ""2000 Maryland Stormwater Management Design Manual"" requires a reduction on 20% of existing impervious to meet stormwater management requirements and, in this project, an impervious area reduction of 38% was achieved. If by reducing the existing impervious area by 38%, does our project meet the requirement of the credit?" "No, the proposal to reduce the impervious area below the existing condition does not fully meet the intent of LEED SS credit 6.2. The intent of SS credit 6.2 is to reduce water pollution by reducing impervious cover, increasing onsite infiltration, eliminating sources of contaminants, and removing pollution from stormwater runoff. While the 38% reduction of impervious cover may qualify for SS credit 6.1 (see Option 2), the runoff from 90% of the average annual rainfall over the remaining impervious cover must be treated using acceptable best management practices like those found in the 2000 Maryland Stormwater Design Manual. Reduction of impervious area as the sole justification for the credit is not acceptable. Note: Reduction of imperviousness by itself does not meet the stormwater management requirements found within The 2000 Maryland Stormwater Design Manual. However, reducing impervious coverage will reduce the required treatment volumes. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2100" "2008-04-24" "New Construction, Schools - New Construction, Core and Shell" "The infill project we are currently working on requires rainfall onsite to be deposited in existing drainage and combined sewer networks at the same rates as the predevelopment conditions. The City of Sacramento has mandated that we refrain from drainage shed-swapping. This requirement requires 0.60 acres of the 2.51 acre site to be drained to the combined sewer. In order to meet the requirements for SSc6.2, we\'ve currently designed 2 stormfilter structures to treat 91% of the average annual rainfall to 90% TSS. One treated outfall connects to a dedicated drainage system while the other connects to a combined sewer. As an alternative to using 2 stormfilter structures, we propose to omit one of the filters and to use one stormfilter in order to treat only the portion of the site that flows to the dedicated drainage system. Our reasoning is that constructing, transporting, and installing a treatment structure that discharges to a combined sewer would not make economic or environmental sense. The treated outflow from the site would be much cleaner than the contents of the combined sewer. While our proposed solution does not meet the letter of the SSc6.2 requirements, we believe that, at the bottom line, it\'s a more sustainable approach, and that it meets the intent of SS6.2. Using our proposed approach, would our project still quality for the SSc6.2 credit?" "The alternative of deleting the second filter that is intended to treat the site flows that are discharge to the combined sewer is not acceptable. TSS that is discharged to the combined sewer must be treated at some point in the total cycle, and untreated discharge from the site implies that treatment must occur downstream from the subject property. The intent of this credit is to minimize site impacts on downstream conditions. Even though the site discharge is into a combined sewer, treatment for TSS is still required prior to reuse or discharge of the treated water from the treatment plant. Reducing TSS at the site translates to less treatment for TSS downstream. Please see Credit Interpretation Ruling dated 3/30/2005 for a similar response to this situation. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2268" "2008-08-22" "New Construction, Existing Buildings, Core and Shell, Schools - New Construction" "The intent of this credit is to reduce or eliminate water pollution by eliminating sources of contaminants and removing pollutants from stormwater runoff. To achieve this, a stormwater management plan must be implemented that captures and treats the stormwater runoff from 90% of the average annual rainfall (1-inch, part of a humid watershed) for the entire LEED Boundary using acceptable best management practices (BMPs) that are capable of removing 80% of the average annual post-development total suspended solids (TSS) load. The proposed site is part of a university located in an urban area and is approximately 6.75 acres with a building footprint of 5.94 acres. The project consists of a parking garage and mechanical space that are entirely underground, and four buildings at the surface. The four buildings that emerge at the surface are connected by the subsurface portion of the building and support both green and conventional roofs. Pedestrian walkways, landscaped open space and a water quality swale make up the balance of the site at the surface. The majority of the stormwater runoff from the site is treated by the large water quality swale at the southern end of the site and water quality units before being reused for irrigation on site. There is a proposed infiltration system in the southwest corner of the site, located in the small portion of the site not directly over the building footprint. Portions of the conventional roof areas (approximately 10% of the site area) cannot be directed towards the water quality swale or the infiltration system due to their location on site. Therefore these roof drains are proposed to be directly discharged to the city stormwater system north of the site. Sources of TSS are generally from automobiles, oil, grease, salt, sediment and debris. The major sources of TSS are paved areas and parking lots where the materials listed above are found. The Massachusetts Stormwater Policy from the Massachusetts DEP considers roof runoff clean, since roofs are presumed to be free of sediment and debris and therefore relatively free of pollutants or TSS. The Massachusetts DEP does not require treatment of roof runoff because it is expected to generate close to zero pounds of TSS. Thus, the 80% removal requirement is not applicable. It is understood that the USGBC requires stormwater runoff from the entire LEED Boundary to be treated, although the Massachusetts DEP allows roof runoff to be discharged directly without treatment. This project does meet the credit intent without treating roof runoff since the relatively clean roof runoff would not contribute to water pollution downstream. Previous LEED certified projects for this university have achieved a point for this credit while not treating roof runoff and stating that roof runoff is considered clean by the State of Massachusetts. We would like to confirm that this is the position that all USGBC reviewers will take when awarding this credit." "Roof runoff is not exempt from the treatment requirements of this credit. See previous CIR ruling dated 11/01/2004. In addition, previous LEED reviews are not precedent setting. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2515" "2009-04-09" "New Construction, Core and Shell, Schools - New Construction" "Site Conditions - The site consists of 4.74 acres located on the north side of Ballenger Creek Drive and south of interstate 70. The majority of the site has been graded to be relatively flat with slopes of approximately 3% to 4%. Along the sites eastern boundary a large swale conveys drainage to a 4\' x 12\' concrete box culvert under Ballenger Creek Drive. The constructed portion of the site has approximately 24,000 sq. ft of paving for a parking lot. A pre-existing storm sewer system runs through the site and conveys drainage from the adjacent commercial site to the west through the site to the existing storm drain system in Ballenger Creek Drive. The site drainage from this area and the site is conveyed to a regional Stormwater management pond. The pond was designed in accordance with the MD 2000 Stormwater Management Regulations and follows the guidelines of the Maryland Stormwater Design Manual. The manual was used as a standard by USGBC when developing the requirements and guidelines for the credit. The pond was approved by the City of Frederick in 1998. This pond was designed to handle hundreds of acres in the region. Our Request - We are asking for clarification on whether or not our off-site pond and our approach qualify the project for the credit. Under the regulations in effect at that time, the 2 year, 10 year and 100 year storms were controlled for quantity within the pond. Extended detention of the 1 year storm was used in the pond for quality. All design storms are 24 hour storms. The 1 year extended detention meets the current MD 2000 Regulations for Channel Protection volume (Cpv). Our approach in meeting the requirements of this credit are through Option 1, section 2 - ""Provide a narrative describing.."", as we cannot get design computations for the Stormwater management pond. Water quality is addressed on site with structural BMP\'s. Although the post-development discharge from this site is higher than the pre-development discharge because it is not managed on site, we believe we meet the credits\' intent by channeling Stormwater to a detention pond, managing quality with structural BMP\'s and protecting streams from Peak discharge rates." "As noted in LEED-NC v2.2 CIR ruling dated 9/4/2006 for SSc6.2, an off-site stormwater management system in a campus (or master-planned) context can be used to achieve SSc6.2 provided that the stormwater management system meets credit requirements for all areas that it serves. The applicant will need to provide calculations demonstrating that the required rainfall amount, as described on p. 97 of the LEED CSv2.0 Reference Guide, as applied to all areas discharging to the off-site pond, receives the requisite level of treatment. In addition, the applicant will need to provide a narrative to demonstrate that it is appropriate that this project is considered in the context of the LEED-NC Application Guide for Multiple Buildings and On-Campus Building Projects (AGMBC). A comparable CIR Ruling dated 8/22/2008 for SSc6.1 LEED NCv2.2 also appears to be applicable to this project. It states, ""the requirements for credit SSc6.1 can be met by demonstrating that the existing (or improved) stormwater management systems that serve the LEED Site Boundary meet the LEED requirements for all areas within the site serviced by those systems."" The applicable LEED requirements for this project appears to be those outlined in Option 1-b: Stream Channel Protection, since the post-development quantity exceeds the pre-development quantity. To comply with this option, the project will have to demonstrate both quantity control strategies and stream channel protection strategies as part of the stormwater management plan. The off-site existing pond could be used as a stream channel protection strategy via rate reduction; if calculations are performed to confirm that the pond is appropriately sized for this purpose. Quantity control strategies could include on-site infiltration areas, rainwater catchment and reuse systems, etc.\n\nUpdate April 15, 2011: Please note that all 2009 projects in multiple building situations must follow the 2010 Application Guide for Multiple Buildings and On-Campus Building Projects, located here: https://www.usgbc.org/ShowFile.aspx?DocumentID=7987. 2009 project teams should check this document for up to date guidance on all multiple building issues. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2537" "2009-04-06" "New Construction, Core and Shell, Schools - New Construction" "Short of credit acceptance, please comment on whether the following conditions are likely to be sufficient for compliance, and if not what additional measures would need to be taken. Reduce Impervious Cover: The subject site is part of Mark Center Plaza 1, which is part of a larger development, the Mark Center area of Alexandria. The Winkler Botanical Preserve Pond, treats runoff from the subject site as well as a large portion of the Mark Center area, was designed and constructed with future urban development in mind and with a purpose of treating stormwater runoff from a large, relatively impervious urban area. Prior to construction of the Winkler Botanical Preserve Pond, which treats all runoff from the subject site, the Winkler Botanical Preserve was created. This preserve was created as part of the development of Mark Center Plaza 1A & 1B (which includes the subject site) and is approximately 40 acres of undeveloped, forested land which was dedicated to the City of Alexandria as an area that cannot be developed in the future. Because such a large area of land, which is located adjacent to the subject property and helps to treat runoff from the subject site before it enters the Winkler Botanical Preserve Pond, has been dedicated for preservation, the stormwater management plan for the Mark Center area, which includes the subject site, includes significant steps to reduce impervious area in an urban setting to the greatest extent possible. Promote Infiltration: The subject site provides approximately 30% vegetated open space, which helps to promote infiltration. In addition, all runoff from the subject site is conveyed via open channels through the above referenced Winkler Botanical Preserve and into the Winkler Botanical Preserve Pond. Because all runoff from the site flows through open channel streams in an undeveloped setting that has been designed to reduce velocities to the greatest extent possible, a significant amount of runoff leaving the site will infiltrate prior to reaching the Winkler Botanical Preserve Pond. BMPs Treat Runoff Capable of Removing 80% Total Suspended Solids: As mentioned above, runoff from the subject site flows into Winkler Botanical Preserve Pond, which is a wet pond. Virginia and City of Alexandria Stormwater Management regulations are designed to promote removal of Phosphorus in lieu of Total Suspended Solids (TSS), so the design of the pond was not intended to quantify removal of TSS. However, as shown on the attached research summary, studies have shown that wet ponds remove 80% - 90% of total suspended solids. Detailed calculations will be provided to quantify TSS removal and demonstrate that the Winkler Botanical Preserve Pond does remove 80% TSS." "The applicant is requesting confirmation regarding the use of several stormwater management strategies to achieve SS credits 6.1 and 6.2 for their site, which is part of a larger development. The proposed strategies include impervious area reduction, infiltration (through open space and redirection of runoff through an existing botanical preserve), and the use of an existing detention pond to collect and treat stormwater. The applicant has explained that the project reduces impervious area because their design proposes less impervious cover than the site was originally allowed, based on the design of an existing regional stormwater management pond. However, reduction of impervious area should not be based on what may be allowed by local zoning or existing infrastructure. Rather, it should be based on what has been used within the project\'s development footprint (e.g., alternative pavements, green roofs) to alter the nature of proposed hardscapes. To promote infiltration, the applicant has stated that they will provide at least 30% open space on the project, as well as convey the runoff via open channels through an adjacent natural area. Recognizing that the intent of the stormwater credits are to limit disruption of natural hydrology and reduce or eliminate water pollution by removing pollutants from runoff, merely conveying runoff onto an adjacent natural area, as described, is not adequate. Treatment of stormwater runoff within the project\'s development footprint should be promoted to prevent degradation of any adjacent highly valued ecosystems. The existing pond could be used to meet SS credit 6.2, but the applicant must demonstrate that runoff is conveyed to the pond in a stable and non-erosive manner. The open ""streams"" through the botanical preserve are equally, if not more important and warrant protection too. In addition, the pond must be sized to adequately accommodate the entire site for which it serves. The project team must either demonstrate that the credit requirements for SSc6.2 have been satisfied for the area bounded by the LEED project boundary or the entire campus. Based on the narrative provided, it appears that a substantial amount of stormwater is distributed as runoff to the adjacent Winkler Botanical Preserve. This runoff must be treated within the LEED project boundary if the project team is attempting to demonstrate compliance for the LEED project boundary. The campus compliance path outlined by the AGMBC requires the aggregate data for the campus/development be used to complete the LEED Submittal Template. Additionally, please note that attachments are not included in CIR submissions.\n\nUpdate April 15, 2011: Please note that all 2009 projects in multiple building situations must follow the 2010 Application Guide for Multiple Buildings and On-Campus Building Projects, located here: https://www.usgbc.org/ShowFile.aspx?DocumentID=7987. 2009 project teams should check this document for up to date guidance on all multiple building issues. " "None" "None" "LEED Interpretation" "2611" "2009-06-18" "New Construction, Core and Shell, Schools - New Construction" "The project is divided up into four drainage areas. At the outlet of each area, a new Stormceptor Water Quality structure will be added. The Stormceptor structures have been designed and analyzed by the Manufacturer based on the total area the structure receives from the respective drainage area along with the percent imperviousness within that area. The manufacturer can then determine the amount of total suspended solids (TSS) that are removed for each structure. The Stormceptor structures, manufactured by Rinker material, have previously been approved by LEED as a sufficient means of meeting Credit 6.2. However, the past approvals have been based on particle size distribution groups (PSD) that differ from the one proposed here. Our project will be designed using a PSD group (OK-110) approved and used in the local community and is as follows: Particle Size (" "The applicant is requesting confirmation of whether the particle size distribution (PSD) group used in testing the removal efficiency of the proposed equipment is appropriate. Structural controls, including Stormceptor Water Quality structures, can be an acceptable means of achieving this credit. Based on the data provided, the use of this PSD group is considered acceptable because it appears to conform to accepted protocol for BMP monitoring." "None" "None" "LEED Interpretation" "3110" "2004-11-01" "New Construction, Schools - New Construction, Core and Shell" "The intent of Credit SS-6.2, as we interpret from the stated Credit Intent and subsequent CIRs, is to minimize the disruption and pollution of natural water bodies by contaminated stormwater. To meet the Credit Intent, the Credit Requirements specify active TP and TSS treatment of stormwater, using BMPs that reduce the percentage of contaminants in the runoff. A subsequent Credit Interpretation Ruling (dated 2/28/02) has allowed projects to achieve partial credit equivalency through preventative means (using low-phosphorus cleaning agents and minimizing fertilization of plantings) rather than active treatment of stormwater. Our project, an urban convention center that covers 97 percent of its site, proposes credit equivalency for demonstrating that the absolute levels of TSS and TP in the runoff meet strict municipal and state standards for ""clean"" stormwater, and therefore qualify for the credit with minimal active treatment.\n\nThe common contaminants for stormwater include dirt, oil, salt, garbage, fertilizers, pesticides, and animal excrement picked up from roads, parking lots and lawns. Roof runoff, by comparison, can be free of many of these contaminants. Roof runoff can therefore obtain the same level of water purity, with little or no treatment, that would be achieved by actively removing TSS and TP from full site runoff.\n\nSince an absolute threshold of TSS/gallon or TP/gallon has not been developed for the LEED program, we submit that the approvals our project received to discharge runoff from our roof directly into Lake Michigan constitute a definition of ""clean"" runoff. Water quality tests were taken from the roof of the existing convention center building to which our project will be an expansion. These tests were submitted to several municipal and state agencies to confirm that any contaminants in the water were at or below the levels defined in the applicable regulatory standards (results of the water tests can be submitted with the credit application). The Chicago Department of Water Management and Chicago Department of Environment approved the roof runoff as safe for discharge directly into Lake Michigan. As a result, our project is building a 3100 ft long tunnel from the site to the Lake to enable this direct discharge (the tunnel separates the stormwater from the city\'s combined sewer system, and prevents transport of existing contaminants in the site\'s soil).\n\nFor the remaining non-roof site runoff (3% of site), the City of Chicago has determined that first-flush treatment is to be provided. First flush treatment, which is a common method of reducing TSS and TP, works by storing or diverting an initial volume of runoff, with the remaining runoff allowed to flow unimpeded to its discharge point. The first flush washes up to the 85th percentile of pollutants from a site, leaving the remaining runoff clean. For this project, first flush, as determined by the City of Chicago Department of Water Management, is a volume of water equivalent to the detention volume for a 1 year storm event, with a release rate determined appropriate to the project site. This method has been employed for the recently completed Soldier Field project, to the Lake Michigan Federations satisfaction. The first flush will be stored in an underground pipe, with the stored volume discharged to the existing City combined sewer system. The remaining runoff volume will be directed to the new ""clean stormwater"" tunnel that discharges in Lake Michigan.\n\nIn conclusion, we propose the following actions undertaken by this project constitute credit equivalency: 1) water quality testing of stormwater on existing facility roof; 2) approval by municipal and state agencies for direct discharge to accepting water body, based on water quality tests; and 3) development of stormwater infrastructure to take clean runoff directly from the roof and site (after first-flush diversion) to the accepting water body.\n " "Although the proposed strategies are laudable, they do not satisfy the requirements of the credit. SSc6.2 requires the treatment of stormwater runoff, therefore a direct discharge to Lake Michigan, even in this specialized case, does not satisfy the credit requirements. \n\nCombined sewer overflows (CSOs) represent a major water quality problem in many parts of the U.S., including Chicago. Strategies that disconnect stormwater runoff from the CSS, thereby reducing the potential for overflows, should be encouraged. By separating clean roof runoff from the CSS and properly treating the first flush from the non-roof areas the project can make a significant improvement to local waterbodies.\n\nSince CSO reduction is not adequately addressed in the framework of the stormwater management credits, the project team could pursue an innovation credit in this regard. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "3122" "2005-03-30" "New Construction, Core and Shell, Schools - New Construction" "Focus of Interpretation: Location of Treatment Facilities\nThe site is located in an expansive urban context (City of Chicago) and is served by a municipal stormwater system that filters run-off to levels that exceed the credit requirements. Based on the following discussion, we would like to use the municipal stormwater filtration system as the basis for earning this point.\nA whole systems approach was used in assessing the specific aspects of this project and it\'s relationship to existing stormwater infrastructure. Below is the rational for considering existing off-site treatment for this site as a preferred option to constructing new on-site treatment:\n1) City owned and operated filtration facilities are already constructed and in place to treat the stormwater.\nThe City of Chicago requires that all stormwater be funneled to the public right of way. In this case, the public right of way consists of a street (a public right of way in the form of open water such as a creek, river or lake is not available). Therefore all run-off from the site must be funneled to the street (municipal stormwater system) and must pass through the municipal water treatment plant serving the system.\nTherefore, on-site filtration would not allow for a reduction in the municipal infrastructure demand by diverting storm water to a natural water course.\n2) On-site in-filtration to re-charge the aquifer or to provide natural treatment of run-off is not feasible because the sub-soils have a low peculation rate.\n3) Since adequate treatment already exists, adding an on-site filtration system unnecessarily increases the demand on resources and creates excessive redundancy.\nThe new design decreases the impact on the municipal system by reducing the quantity of run-off by almost 20% (through evapo-transpiration). The new site use will decrease levels of pollutants and sediment required to be filtered. The new use is much cleaner (Retail) than the previous use (Automotive repair and Trucking).\nTherefore, on-site filtration would not be an improvement over the life cycle of the stormwater filtration provided by the municipality. In fact the life cycle impact may actually be worse for on-site filtration due to decreased efficiencies:\na) On-site filtration will require the use of additional material and embodied energy for tanks and piping.\nb) This site, which is very flat, will also require a pump, electricity to run the pump and on-site infrastructure to support the pump (wiring, conduit, switch and controls).\nc) Regular maintenance and cleaning of the filters will require transportation and energy that is likely to exceed that required for the maintenance of the existing centralized system.\n4) We are dramatically reducing the rate of run-off from the site.\nTherefore, we are helping to spread out concentrated storm loads impacting the City\'s treatment system and reducing the potential that water from the site would bi-pass city filtration due to overload of the system.\n5) Precedent has been established defining that existing infrastructure beyond the immediate scope of a project must be considered as part of a LEED Certification:\nExample -- For new buildings utilizing an existing central chiller, existing CFC refrigerants must be replaced for the project(s) to achieve Certification due to non-compliance with pre-requisites.\nIf existing non-compliant infrastructure systems serving a project are taken into consideration as part of certification, can existing compliant infrastructure systems be taken into consideration for certification as well?\nThank you for your consideration." "Relying on the municipal stormwater system for stormwater treatment is not an acceptable strategy for this credit. Part of the goal of this credit is to decrease the burden on municipal stormwater systems. The described strategy does not achieve this goal, and does not meet the intent of the credit. While an integrated stormwater treatment system for a campus might be acceptable, reliance on the municipal stormwater system will not qualify for the credit.\n\nThe submitter states that runoff will be decreased by 20%. If this is sufficient to infiltrate the first flush (first 1"" of rainfall), then the project may be able to achieve this credit. See CIR SSc6.2 3/11/2003 for more information. Applicable Internationally. " "10114, 5272" "None" "X" "LEED Interpretation" "3127" "2002-02-28" "New Construction, Schools - New Construction, Core and Shell" "The project is located in central Allentown, Pennsylvania, and the site itself is located in a zone of sinkholes and unstable limestone substructure. Our geotechnical advisors have recommended that there be no water retention at all on the site, including the tanks that would be necessary to retain stormwater before releasing it through a sand filtration system. They have also advised that no water be allowed to enter the ground through permeable landscaping, as that will significantly increase the chances of sinkhole formation or movement.\n\nThis project is installing in all stormwater runoff lines a series of ""Snouts"" from Best Management Products, which are fixtures placed over stormwater inlet lines in sumps that force water settlement before it passes on into the outfall pipe. BMP will certify that these snouts, as implemented in our design, will achieve better than the target 80% removal of TSS from all site stormwater before it enters the city stormwater systems. However, BMP will not certify that these products will remove any particular amount of TP. Rather, they note that Phosphorus will both attach itself to suspended solids -- which would be removed with the TSS -- and some Phosphorus will remain in solution, which their system will not remove.\n\nTo achieve the intent of the credit, we propose to implement a series of control measures in building operations to reduce Phosphorus levels entering runoff stormwater. Because the project is on an urban site, most Phosphorus would be introduced to the site through either landscape fertilizers or through landscape, plaza, and building cleaning materials. The Phosphrus control plan we intend to implement will address these three areas as such:\n\n1) The landscape vegetation is selected that requires low to no regular fertilization. Trees are contained in underground boxes with solid paving to within 6 inches of the trunks, and they are injection fertilized.\n\n2) The plaza cleaning plan (as proscribed in the building specifications) will use low Phosphate or Phosphate-free citrus based cleaning agents.\n\n3) The building window-washing plan (as proscribed in the building specifications) will use low Phosphate or Phosphate-free citrus based cleaning agents.\n\nWill such a strategy of reducing phosphorus entering the stormwater streat rather than removing it after the fact satisfy the intent of the credit?\n " "From the description provided, the \'snouts\' appear to meet the credit requirements, especially for use in the karst topography area. It will be necessary to provide documentation in the form of specifications and drawings from both the manufacturer and the civil engineer supporting the treatment claims for contaminant removal, as well as a letter from the geotechnical advisor outlining the recommendations made.\n\nRemoving contaminants before they get into the water is also a strategy that meets the intent of the credit. To guarantee that the methods proposed will be followed for the life of the building, it will be necessary to include the usage plans for cleaning agents and fertilizers in the building operations manual, as well as in the specifications. It will also be necessary to show through calculations the total phosphorous that will potentially be used and how much ultimately will be expended into the site (which must be at least 40% less)." "None" "None" "LEED Interpretation" "5214" "2009-05-06" "New Construction, Schools - New Construction, Core and Shell" "Our project site is a University Campus in North Carolina. Part of the LEED boundary site area includes a natural forested and grassy area which we are not disturbing as part of the project. For the LEED quality point we need to capture and treat 90% of the runoff from the annual average rainfall (1"" for our site-humid area) within the LEED boundary area. The SCS soil survey lists the soil type on site to be Hiwassee Loam, hydrologic soil group B. The SCS curve number for grassed pervious areas would be 61. According to Table 2.1 (runoff depth table) in SCS TR-55 (Urban Hydrology for Small Watersheds ) a 1"" rainfall depth produces no runoff for curve numbers below 70. Since no runoff will be produced in this area for the 1"" rainfall event, how do we show in this in LEED quality point worksheet? Show it as a non-structural BMP infiltration area?" "The project is seeking clarification for how stormwater infiltrated on-site should be documented for certification. Per the LEED Reference Guide, water that is infiltrated on-site is assumed to be 100% treated for the purpose of this credit and is considered to be a non-structural control. Therefore, the Non-Structural Controls section of the Submittal Template should be completed, stating the percentage of stormwater that will be infiltrated in this area. Applicable Internationally. " "None" "None" "X"